Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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/mount.h>
17#include <linux/init.h>
18#include <linux/user_namespace.h>
19
20#include "sysfs.h"
21
22static struct kernfs_root *sysfs_root;
23struct kernfs_node *sysfs_root_kn;
24
25static struct dentry *sysfs_mount(struct file_system_type *fs_type,
26 int flags, const char *dev_name, void *data)
27{
28 struct dentry *root;
29 void *ns;
30 bool new_sb;
31
32 if (!(flags & MS_KERNMOUNT)) {
33 if (!capable(CAP_SYS_ADMIN) && !fs_fully_visible(fs_type))
34 return ERR_PTR(-EPERM);
35
36 if (!kobj_ns_current_may_mount(KOBJ_NS_TYPE_NET))
37 return ERR_PTR(-EPERM);
38 }
39
40 ns = kobj_ns_grab_current(KOBJ_NS_TYPE_NET);
41 root = kernfs_mount_ns(fs_type, flags, sysfs_root, &new_sb, ns);
42 if (IS_ERR(root) || !new_sb)
43 kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
44 return root;
45}
46
47static void sysfs_kill_sb(struct super_block *sb)
48{
49 void *ns = (void *)kernfs_super_ns(sb);
50
51 kernfs_kill_sb(sb);
52 kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
53}
54
55static struct file_system_type sysfs_fs_type = {
56 .name = "sysfs",
57 .mount = sysfs_mount,
58 .kill_sb = sysfs_kill_sb,
59 .fs_flags = FS_USERNS_MOUNT,
60};
61
62int __init sysfs_init(void)
63{
64 int err;
65
66 sysfs_root = kernfs_create_root(NULL, 0, NULL);
67 if (IS_ERR(sysfs_root))
68 return PTR_ERR(sysfs_root);
69
70 sysfs_root_kn = sysfs_root->kn;
71
72 err = register_filesystem(&sysfs_fs_type);
73 if (err) {
74 kernfs_destroy_root(sysfs_root);
75 return err;
76 }
77
78 return 0;
79}