2 * fs/sysfs/symlink.c - operations for initializing and mounting sysfs
4 * Copyright (c) 2001-3 Patrick Mochel
5 * Copyright (c) 2007 SUSE Linux Products GmbH
6 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
8 * This file is released under the GPLv2.
10 * Please see Documentation/filesystems/sysfs.txt for more information.
16 #include <linux/mount.h>
17 #include <linux/init.h>
18 #include <linux/user_namespace.h>
22 static struct kernfs_root *sysfs_root;
23 struct sysfs_dirent *sysfs_root_sd;
25 static struct dentry *sysfs_mount(struct file_system_type *fs_type,
26 int flags, const char *dev_name, void *data)
31 if (!(flags & MS_KERNMOUNT)) {
32 if (!capable(CAP_SYS_ADMIN) && !fs_fully_visible(fs_type))
33 return ERR_PTR(-EPERM);
35 if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET))
36 return ERR_PTR(-EPERM);
39 ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
40 root = kernfs_mount_ns(fs_type, flags, sysfs_root, ns);
42 kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
46 static void sysfs_kill_sb(struct super_block *sb)
49 kobj_ns_drop(KOBJ_NS_TYPE_NET, (void *)kernfs_super_ns(sb));
52 static struct file_system_type sysfs_fs_type = {
55 .kill_sb = sysfs_kill_sb,
56 .fs_flags = FS_USERNS_MOUNT,
59 int __init sysfs_init(void)
63 sysfs_root = kernfs_create_root(NULL);
64 if (IS_ERR(sysfs_root))
65 return PTR_ERR(sysfs_root);
67 sysfs_root_sd = sysfs_root->sd;
69 err = register_filesystem(&sysfs_fs_type);
71 kernfs_destroy_root(sysfs_root);