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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 root->d_sb->s_iflags |= SB_I_USERNS_VISIBLE;
45
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/mount.h>
17#include <linux/pagemap.h>
18#include <linux/init.h>
19#include <linux/module.h>
20#include <linux/magic.h>
21#include <linux/slab.h>
22
23#include "sysfs.h"
24
25
26static struct vfsmount *sysfs_mnt;
27struct kmem_cache *sysfs_dir_cachep;
28
29static const struct super_operations sysfs_ops = {
30 .statfs = simple_statfs,
31 .drop_inode = generic_delete_inode,
32 .evict_inode = sysfs_evict_inode,
33};
34
35struct sysfs_dirent sysfs_root = {
36 .s_name = "",
37 .s_count = ATOMIC_INIT(1),
38 .s_flags = SYSFS_DIR | (KOBJ_NS_TYPE_NONE << SYSFS_NS_TYPE_SHIFT),
39 .s_mode = S_IFDIR | S_IRUGO | S_IXUGO,
40 .s_ino = 1,
41};
42
43static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
44{
45 struct inode *inode;
46 struct dentry *root;
47
48 sb->s_blocksize = PAGE_CACHE_SIZE;
49 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
50 sb->s_magic = SYSFS_MAGIC;
51 sb->s_op = &sysfs_ops;
52 sb->s_time_gran = 1;
53
54 /* get root inode, initialize and unlock it */
55 mutex_lock(&sysfs_mutex);
56 inode = sysfs_get_inode(sb, &sysfs_root);
57 mutex_unlock(&sysfs_mutex);
58 if (!inode) {
59 pr_debug("sysfs: could not get root inode\n");
60 return -ENOMEM;
61 }
62
63 /* instantiate and link root dentry */
64 root = d_make_root(inode);
65 if (!root) {
66 pr_debug("%s: could not get root dentry!\n",__func__);
67 return -ENOMEM;
68 }
69 root->d_fsdata = &sysfs_root;
70 sb->s_root = root;
71 return 0;
72}
73
74static int sysfs_test_super(struct super_block *sb, void *data)
75{
76 struct sysfs_super_info *sb_info = sysfs_info(sb);
77 struct sysfs_super_info *info = data;
78 enum kobj_ns_type type;
79 int found = 1;
80
81 for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) {
82 if (sb_info->ns[type] != info->ns[type])
83 found = 0;
84 }
85 return found;
86}
87
88static int sysfs_set_super(struct super_block *sb, void *data)
89{
90 int error;
91 error = set_anon_super(sb, data);
92 if (!error)
93 sb->s_fs_info = data;
94 return error;
95}
96
97static void free_sysfs_super_info(struct sysfs_super_info *info)
98{
99 int type;
100 for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++)
101 kobj_ns_drop(type, info->ns[type]);
102 kfree(info);
103}
104
105static struct dentry *sysfs_mount(struct file_system_type *fs_type,
106 int flags, const char *dev_name, void *data)
107{
108 struct sysfs_super_info *info;
109 enum kobj_ns_type type;
110 struct super_block *sb;
111 int error;
112
113 info = kzalloc(sizeof(*info), GFP_KERNEL);
114 if (!info)
115 return ERR_PTR(-ENOMEM);
116
117 for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++)
118 info->ns[type] = kobj_ns_grab_current(type);
119
120 sb = sget(fs_type, sysfs_test_super, sysfs_set_super, info);
121 if (IS_ERR(sb) || sb->s_fs_info != info)
122 free_sysfs_super_info(info);
123 if (IS_ERR(sb))
124 return ERR_CAST(sb);
125 if (!sb->s_root) {
126 sb->s_flags = flags;
127 error = sysfs_fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
128 if (error) {
129 deactivate_locked_super(sb);
130 return ERR_PTR(error);
131 }
132 sb->s_flags |= MS_ACTIVE;
133 }
134
135 return dget(sb->s_root);
136}
137
138static void sysfs_kill_sb(struct super_block *sb)
139{
140 struct sysfs_super_info *info = sysfs_info(sb);
141 /* Remove the superblock from fs_supers/s_instances
142 * so we can't find it, before freeing sysfs_super_info.
143 */
144 kill_anon_super(sb);
145 free_sysfs_super_info(info);
146}
147
148static struct file_system_type sysfs_fs_type = {
149 .name = "sysfs",
150 .mount = sysfs_mount,
151 .kill_sb = sysfs_kill_sb,
152};
153
154int __init sysfs_init(void)
155{
156 int err = -ENOMEM;
157
158 sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
159 sizeof(struct sysfs_dirent),
160 0, 0, NULL);
161 if (!sysfs_dir_cachep)
162 goto out;
163
164 err = sysfs_inode_init();
165 if (err)
166 goto out_err;
167
168 err = register_filesystem(&sysfs_fs_type);
169 if (!err) {
170 sysfs_mnt = kern_mount(&sysfs_fs_type);
171 if (IS_ERR(sysfs_mnt)) {
172 printk(KERN_ERR "sysfs: could not mount!\n");
173 err = PTR_ERR(sysfs_mnt);
174 sysfs_mnt = NULL;
175 unregister_filesystem(&sysfs_fs_type);
176 goto out_err;
177 }
178 } else
179 goto out_err;
180out:
181 return err;
182out_err:
183 kmem_cache_destroy(sysfs_dir_cachep);
184 sysfs_dir_cachep = NULL;
185 goto out;
186}
187
188#undef sysfs_get
189struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd)
190{
191 return __sysfs_get(sd);
192}
193EXPORT_SYMBOL_GPL(sysfs_get);
194
195#undef sysfs_put
196void sysfs_put(struct sysfs_dirent *sd)
197{
198 __sysfs_put(sd);
199}
200EXPORT_SYMBOL_GPL(sysfs_put);