1/*
 2 * fs/sysfs/symlink.c - operations for initializing and mounting sysfs
 3 *
 4 * Copyright (c) 2001-3 Patrick Mochel
 5 * Copyright (c) 2007 SUSE Linux Products GmbH
 6 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
 7 *
 8 * This file is released under the GPLv2.
 9 *
10 * Please see Documentation/filesystems/sysfs.txt for more information.
11 */
12
13#define DEBUG
14
15#include <linux/fs.h>
16#include <linux/magic.h>
17#include <linux/mount.h>
18#include <linux/init.h>
19#include <linux/user_namespace.h>
20
21#include "sysfs.h"
22
23static struct kernfs_root *sysfs_root;
24struct kernfs_node *sysfs_root_kn;
25
26static struct dentry *sysfs_mount(struct file_system_type *fs_type,
27	int flags, const char *dev_name, void *data)
28{
29	struct dentry *root;
30	void *ns;
31	bool new_sb;
32
33	if (!(flags & MS_KERNMOUNT)) {
34		if (!capable(CAP_SYS_ADMIN) && !fs_fully_visible(fs_type))
35			return ERR_PTR(-EPERM);
36
37		if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET))
38			return ERR_PTR(-EPERM);
39	}
40
41	ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
42	root = kernfs_mount_ns(fs_type, flags, sysfs_root,
43				SYSFS_MAGIC, &new_sb, ns);
44	if (IS_ERR(root) || !new_sb)
45		kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
 
 
 
 
46	return root;
47}
48
49static void sysfs_kill_sb(struct super_block *sb)
50{
51	void *ns = (void *)kernfs_super_ns(sb);
52
53	kernfs_kill_sb(sb);
54	kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
55}
56
57static struct file_system_type sysfs_fs_type = {
58	.name		= "sysfs",
59	.mount		= sysfs_mount,
60	.kill_sb	= sysfs_kill_sb,
61	.fs_flags	= FS_USERNS_MOUNT,
62};
63
64int __init sysfs_init(void)
65{
66	int err;
67
68	sysfs_root = kernfs_create_root(NULL, KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK,
69					NULL);
70	if (IS_ERR(sysfs_root))
71		return PTR_ERR(sysfs_root);
72
73	sysfs_root_kn = sysfs_root->kn;
74
75	err = register_filesystem(&sysfs_fs_type);
76	if (err) {
77		kernfs_destroy_root(sysfs_root);
78		return err;
79	}
80
81	return 0;
82}

 1/*
 2 * fs/sysfs/symlink.c - operations for initializing and mounting sysfs
 3 *
 4 * Copyright (c) 2001-3 Patrick Mochel
 5 * Copyright (c) 2007 SUSE Linux Products GmbH
 6 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
 7 *
 8 * This file is released under the GPLv2.
 9 *
10 * Please see Documentation/filesystems/sysfs.txt for more information.
11 */
12
13#define DEBUG
14
15#include <linux/fs.h>
16#include <linux/magic.h>
17#include <linux/mount.h>
18#include <linux/init.h>
19#include <linux/user_namespace.h>
20
21#include "sysfs.h"
22
23static struct kernfs_root *sysfs_root;
24struct kernfs_node *sysfs_root_kn;
25
26static struct dentry *sysfs_mount(struct file_system_type *fs_type,
27	int flags, const char *dev_name, void *data)
28{
29	struct dentry *root;
30	void *ns;
31	bool new_sb;
32
33	if (!(flags & MS_KERNMOUNT)) {
 
 
 
34		if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET))
35			return ERR_PTR(-EPERM);
36	}
37
38	ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
39	root = kernfs_mount_ns(fs_type, flags, sysfs_root,
40				SYSFS_MAGIC, &new_sb, ns);
41	if (IS_ERR(root) || !new_sb)
42		kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
43	else if (new_sb)
44		/* Userspace would break if executables appear on sysfs */
45		root->d_sb->s_iflags |= SB_I_NOEXEC;
46
47	return root;
48}
49
50static void sysfs_kill_sb(struct super_block *sb)
51{
52	void *ns = (void *)kernfs_super_ns(sb);
53
54	kernfs_kill_sb(sb);
55	kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
56}
57
58static struct file_system_type sysfs_fs_type = {
59	.name		= "sysfs",
60	.mount		= sysfs_mount,
61	.kill_sb	= sysfs_kill_sb,
62	.fs_flags	= FS_USERNS_VISIBLE | FS_USERNS_MOUNT,
63};
64
65int __init sysfs_init(void)
66{
67	int err;
68
69	sysfs_root = kernfs_create_root(NULL, KERNFS_ROOT_EXTRA_OPEN_PERM_CHECK,
70					NULL);
71	if (IS_ERR(sysfs_root))
72		return PTR_ERR(sysfs_root);
73
74	sysfs_root_kn = sysfs_root->kn;
75
76	err = register_filesystem(&sysfs_fs_type);
77	if (err) {
78		kernfs_destroy_root(sysfs_root);
79		return err;
80	}
81
82	return 0;
83}