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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#include <linux/user_namespace.h>
23
24#include "sysfs.h"
25
26
27static struct vfsmount *sysfs_mnt;
28struct kmem_cache *sysfs_dir_cachep;
29
30static const struct super_operations sysfs_ops = {
31 .statfs = simple_statfs,
32 .drop_inode = generic_delete_inode,
33 .evict_inode = sysfs_evict_inode,
34};
35
36struct sysfs_dirent sysfs_root = {
37 .s_name = "",
38 .s_count = ATOMIC_INIT(1),
39 .s_flags = SYSFS_DIR | (KOBJ_NS_TYPE_NONE << SYSFS_NS_TYPE_SHIFT),
40 .s_mode = S_IFDIR | S_IRUGO | S_IXUGO,
41 .s_ino = 1,
42};
43
44static int sysfs_fill_super(struct super_block *sb, void *data, int silent)
45{
46 struct inode *inode;
47 struct dentry *root;
48
49 sb->s_blocksize = PAGE_CACHE_SIZE;
50 sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
51 sb->s_magic = SYSFS_MAGIC;
52 sb->s_op = &sysfs_ops;
53 sb->s_time_gran = 1;
54
55
56 mutex_lock(&sysfs_mutex);
57 inode = sysfs_get_inode(sb, &sysfs_root);
58 mutex_unlock(&sysfs_mutex);
59 if (!inode) {
60 pr_debug("sysfs: could not get root inode\n");
61 return -ENOMEM;
62 }
63
64
65 root = d_make_root(inode);
66 if (!root) {
67 pr_debug("%s: could not get root dentry!\n",__func__);
68 return -ENOMEM;
69 }
70 root->d_fsdata = &sysfs_root;
71 sb->s_root = root;
72 sb->s_d_op = &sysfs_dentry_ops;
73 return 0;
74}
75
76static int sysfs_test_super(struct super_block *sb, void *data)
77{
78 struct sysfs_super_info *sb_info = sysfs_info(sb);
79 struct sysfs_super_info *info = data;
80 enum kobj_ns_type type;
81 int found = 1;
82
83 for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++) {
84 if (sb_info->ns[type] != info->ns[type])
85 found = 0;
86 }
87 return found;
88}
89
90static int sysfs_set_super(struct super_block *sb, void *data)
91{
92 int error;
93 error = set_anon_super(sb, data);
94 if (!error)
95 sb->s_fs_info = data;
96 return error;
97}
98
99static void free_sysfs_super_info(struct sysfs_super_info *info)
100{
101 int type;
102 for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++)
103 kobj_ns_drop(type, info->ns[type]);
104 kfree(info);
105}
106
107static struct dentry *sysfs_mount(struct file_system_type *fs_type,
108 int flags, const char *dev_name, void *data)
109{
110 struct sysfs_super_info *info;
111 enum kobj_ns_type type;
112 struct super_block *sb;
113 int error;
114
115 if (!(flags & MS_KERNMOUNT) && !current_user_ns()->may_mount_sysfs)
116 return ERR_PTR(-EPERM);
117
118 info = kzalloc(sizeof(*info), GFP_KERNEL);
119 if (!info)
120 return ERR_PTR(-ENOMEM);
121
122 for (type = KOBJ_NS_TYPE_NONE; type < KOBJ_NS_TYPES; type++)
123 info->ns[type] = kobj_ns_grab_current(type);
124
125 sb = sget(fs_type, sysfs_test_super, sysfs_set_super, flags, info);
126 if (IS_ERR(sb) || sb->s_fs_info != info)
127 free_sysfs_super_info(info);
128 if (IS_ERR(sb))
129 return ERR_CAST(sb);
130 if (!sb->s_root) {
131 error = sysfs_fill_super(sb, data, flags & MS_SILENT ? 1 : 0);
132 if (error) {
133 deactivate_locked_super(sb);
134 return ERR_PTR(error);
135 }
136 sb->s_flags |= MS_ACTIVE;
137 }
138
139 return dget(sb->s_root);
140}
141
142static void sysfs_kill_sb(struct super_block *sb)
143{
144 struct sysfs_super_info *info = sysfs_info(sb);
145
146
147
148 kill_anon_super(sb);
149 free_sysfs_super_info(info);
150}
151
152static struct file_system_type sysfs_fs_type = {
153 .name = "sysfs",
154 .mount = sysfs_mount,
155 .kill_sb = sysfs_kill_sb,
156 .fs_flags = FS_USERNS_MOUNT,
157};
158
159int __init sysfs_init(void)
160{
161 int err = -ENOMEM;
162
163 sysfs_dir_cachep = kmem_cache_create("sysfs_dir_cache",
164 sizeof(struct sysfs_dirent),
165 0, 0, NULL);
166 if (!sysfs_dir_cachep)
167 goto out;
168
169 err = sysfs_inode_init();
170 if (err)
171 goto out_err;
172
173 err = register_filesystem(&sysfs_fs_type);
174 if (!err) {
175 sysfs_mnt = kern_mount(&sysfs_fs_type);
176 if (IS_ERR(sysfs_mnt)) {
177 printk(KERN_ERR "sysfs: could not mount!\n");
178 err = PTR_ERR(sysfs_mnt);
179 sysfs_mnt = NULL;
180 unregister_filesystem(&sysfs_fs_type);
181 goto out_err;
182 }
183 } else
184 goto out_err;
185out:
186 return err;
187out_err:
188 kmem_cache_destroy(sysfs_dir_cachep);
189 sysfs_dir_cachep = NULL;
190 goto out;
191}
192
193#undef sysfs_get
194struct sysfs_dirent *sysfs_get(struct sysfs_dirent *sd)
195{
196 return __sysfs_get(sd);
197}
198EXPORT_SYMBOL_GPL(sysfs_get);
199
200#undef sysfs_put
201void sysfs_put(struct sysfs_dirent *sd)
202{
203 __sysfs_put(sd);
204}
205EXPORT_SYMBOL_GPL(sysfs_put);
206
