a7560a0132
While restructuring the [u]mount path, 4b93dc9b1c ("sysfs, kernfs:
prepare mount path for kernfs") incorrectly updated sysfs_kill_sb() so
that it first kills super_block and then tries to dereference its
namespace tag to drop it. Fix it by caching namespace tag before
killing the superblock and then drop the cached namespace tag.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Tested-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Tested-by: Vlastimil Babka <vbabka@suse.cz>
Link: http://lkml.kernel.org/g/20131205031051.GC5135@yliu-dev.sh.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
79 lines
1.6 KiB
C
79 lines
1.6 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 sysfs_dirent *sysfs_root_sd;
|
|
|
|
static struct dentry *sysfs_mount(struct file_system_type *fs_type,
|
|
int flags, const char *dev_name, void *data)
|
|
{
|
|
struct dentry *root;
|
|
void *ns;
|
|
|
|
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, ns);
|
|
if (IS_ERR(root))
|
|
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);
|
|
if (IS_ERR(sysfs_root))
|
|
return PTR_ERR(sysfs_root);
|
|
|
|
sysfs_root_sd = sysfs_root->sd;
|
|
|
|
err = register_filesystem(&sysfs_fs_type);
|
|
if (err) {
|
|
kernfs_destroy_root(sysfs_root);
|
|
return err;
|
|
}
|
|
|
|
return 0;
|
|
}
|