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b67dbf9d GK |
1 | /* |
2 | * inode.c - securityfs | |
3 | * | |
4 | * Copyright (C) 2005 Greg Kroah-Hartman <gregkh@suse.de> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License version | |
8 | * 2 as published by the Free Software Foundation. | |
9 | * | |
10 | * Based on fs/debugfs/inode.c which had the following copyright notice: | |
11 | * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com> | |
12 | * Copyright (C) 2004 IBM Inc. | |
13 | */ | |
14 | ||
15 | /* #define DEBUG */ | |
b67dbf9d GK |
16 | #include <linux/module.h> |
17 | #include <linux/fs.h> | |
18 | #include <linux/mount.h> | |
19 | #include <linux/pagemap.h> | |
20 | #include <linux/init.h> | |
21 | #include <linux/namei.h> | |
22 | #include <linux/security.h> | |
92562927 | 23 | #include <linux/magic.h> |
b67dbf9d GK |
24 | |
25 | static struct vfsmount *mount; | |
26 | static int mount_count; | |
27 | ||
28 | /* | |
29 | * TODO: | |
30 | * I think I can get rid of these default_file_ops, but not quite sure... | |
31 | */ | |
32 | static ssize_t default_read_file(struct file *file, char __user *buf, | |
33 | size_t count, loff_t *ppos) | |
34 | { | |
35 | return 0; | |
36 | } | |
37 | ||
38 | static ssize_t default_write_file(struct file *file, const char __user *buf, | |
39 | size_t count, loff_t *ppos) | |
40 | { | |
41 | return count; | |
42 | } | |
43 | ||
44 | static int default_open(struct inode *inode, struct file *file) | |
45 | { | |
8e18e294 TT |
46 | if (inode->i_private) |
47 | file->private_data = inode->i_private; | |
b67dbf9d GK |
48 | |
49 | return 0; | |
50 | } | |
51 | ||
9c2e08c5 | 52 | static const struct file_operations default_file_ops = { |
b67dbf9d GK |
53 | .read = default_read_file, |
54 | .write = default_write_file, | |
55 | .open = default_open, | |
6038f373 | 56 | .llseek = noop_llseek, |
b67dbf9d GK |
57 | }; |
58 | ||
59 | static struct inode *get_inode(struct super_block *sb, int mode, dev_t dev) | |
60 | { | |
61 | struct inode *inode = new_inode(sb); | |
62 | ||
63 | if (inode) { | |
64 | inode->i_mode = mode; | |
b67dbf9d GK |
65 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; |
66 | switch (mode & S_IFMT) { | |
67 | default: | |
68 | init_special_inode(inode, mode, dev); | |
69 | break; | |
70 | case S_IFREG: | |
71 | inode->i_fop = &default_file_ops; | |
72 | break; | |
73 | case S_IFDIR: | |
74 | inode->i_op = &simple_dir_inode_operations; | |
75 | inode->i_fop = &simple_dir_operations; | |
76 | ||
77 | /* directory inodes start off with i_nlink == 2 (for "." entry) */ | |
d8c76e6f | 78 | inc_nlink(inode); |
b67dbf9d GK |
79 | break; |
80 | } | |
81 | } | |
82 | return inode; | |
83 | } | |
84 | ||
85 | /* SMP-safe */ | |
86 | static int mknod(struct inode *dir, struct dentry *dentry, | |
87 | int mode, dev_t dev) | |
88 | { | |
89 | struct inode *inode; | |
b8bc83ab | 90 | int error = -ENOMEM; |
b67dbf9d GK |
91 | |
92 | if (dentry->d_inode) | |
93 | return -EEXIST; | |
94 | ||
95 | inode = get_inode(dir->i_sb, mode, dev); | |
96 | if (inode) { | |
97 | d_instantiate(dentry, inode); | |
98 | dget(dentry); | |
99 | error = 0; | |
100 | } | |
101 | return error; | |
102 | } | |
103 | ||
104 | static int mkdir(struct inode *dir, struct dentry *dentry, int mode) | |
105 | { | |
106 | int res; | |
107 | ||
108 | mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR; | |
109 | res = mknod(dir, dentry, mode, 0); | |
110 | if (!res) | |
d8c76e6f | 111 | inc_nlink(dir); |
b67dbf9d GK |
112 | return res; |
113 | } | |
114 | ||
115 | static int create(struct inode *dir, struct dentry *dentry, int mode) | |
116 | { | |
117 | mode = (mode & S_IALLUGO) | S_IFREG; | |
118 | return mknod(dir, dentry, mode, 0); | |
119 | } | |
120 | ||
121 | static inline int positive(struct dentry *dentry) | |
122 | { | |
123 | return dentry->d_inode && !d_unhashed(dentry); | |
124 | } | |
125 | ||
126 | static int fill_super(struct super_block *sb, void *data, int silent) | |
127 | { | |
128 | static struct tree_descr files[] = {{""}}; | |
129 | ||
130 | return simple_fill_super(sb, SECURITYFS_MAGIC, files); | |
131 | } | |
132 | ||
454e2398 DH |
133 | static int get_sb(struct file_system_type *fs_type, |
134 | int flags, const char *dev_name, | |
135 | void *data, struct vfsmount *mnt) | |
b67dbf9d | 136 | { |
454e2398 | 137 | return get_sb_single(fs_type, flags, data, fill_super, mnt); |
b67dbf9d GK |
138 | } |
139 | ||
140 | static struct file_system_type fs_type = { | |
141 | .owner = THIS_MODULE, | |
142 | .name = "securityfs", | |
143 | .get_sb = get_sb, | |
144 | .kill_sb = kill_litter_super, | |
145 | }; | |
146 | ||
147 | static int create_by_name(const char *name, mode_t mode, | |
148 | struct dentry *parent, | |
149 | struct dentry **dentry) | |
150 | { | |
151 | int error = 0; | |
152 | ||
153 | *dentry = NULL; | |
154 | ||
155 | /* If the parent is not specified, we create it in the root. | |
156 | * We need the root dentry to do this, which is in the super | |
157 | * block. A pointer to that is in the struct vfsmount that we | |
158 | * have around. | |
159 | */ | |
ef52c75e AV |
160 | if (!parent) |
161 | parent = mount->mnt_sb->s_root; | |
b67dbf9d | 162 | |
1b1dcc1b | 163 | mutex_lock(&parent->d_inode->i_mutex); |
b67dbf9d | 164 | *dentry = lookup_one_len(name, parent, strlen(name)); |
b338cc82 | 165 | if (!IS_ERR(*dentry)) { |
b67dbf9d GK |
166 | if ((mode & S_IFMT) == S_IFDIR) |
167 | error = mkdir(parent->d_inode, *dentry, mode); | |
168 | else | |
169 | error = create(parent->d_inode, *dentry, mode); | |
b8bc83ab TU |
170 | if (error) |
171 | dput(*dentry); | |
b67dbf9d | 172 | } else |
b338cc82 | 173 | error = PTR_ERR(*dentry); |
1b1dcc1b | 174 | mutex_unlock(&parent->d_inode->i_mutex); |
b67dbf9d GK |
175 | |
176 | return error; | |
177 | } | |
178 | ||
179 | /** | |
180 | * securityfs_create_file - create a file in the securityfs filesystem | |
181 | * | |
182 | * @name: a pointer to a string containing the name of the file to create. | |
183 | * @mode: the permission that the file should have | |
184 | * @parent: a pointer to the parent dentry for this file. This should be a | |
3f23d815 | 185 | * directory dentry if set. If this parameter is %NULL, then the |
b67dbf9d GK |
186 | * file will be created in the root of the securityfs filesystem. |
187 | * @data: a pointer to something that the caller will want to get to later | |
8e18e294 | 188 | * on. The inode.i_private pointer will point to this value on |
b67dbf9d GK |
189 | * the open() call. |
190 | * @fops: a pointer to a struct file_operations that should be used for | |
191 | * this file. | |
192 | * | |
193 | * This is the basic "create a file" function for securityfs. It allows for a | |
3f23d815 | 194 | * wide range of flexibility in creating a file, or a directory (if you |
b67dbf9d | 195 | * want to create a directory, the securityfs_create_dir() function is |
3f23d815 | 196 | * recommended to be used instead). |
b67dbf9d | 197 | * |
3f23d815 | 198 | * This function returns a pointer to a dentry if it succeeds. This |
b67dbf9d GK |
199 | * pointer must be passed to the securityfs_remove() function when the file is |
200 | * to be removed (no automatic cleanup happens if your module is unloaded, | |
faa3aad7 SH |
201 | * you are responsible here). If an error occurs, the function will return |
202 | * the erorr value (via ERR_PTR). | |
b67dbf9d | 203 | * |
3f23d815 | 204 | * If securityfs is not enabled in the kernel, the value %-ENODEV is |
faa3aad7 | 205 | * returned. |
b67dbf9d GK |
206 | */ |
207 | struct dentry *securityfs_create_file(const char *name, mode_t mode, | |
208 | struct dentry *parent, void *data, | |
9c2e08c5 | 209 | const struct file_operations *fops) |
b67dbf9d GK |
210 | { |
211 | struct dentry *dentry = NULL; | |
212 | int error; | |
213 | ||
214 | pr_debug("securityfs: creating file '%s'\n",name); | |
215 | ||
1f5ce9e9 | 216 | error = simple_pin_fs(&fs_type, &mount, &mount_count); |
b67dbf9d GK |
217 | if (error) { |
218 | dentry = ERR_PTR(error); | |
219 | goto exit; | |
220 | } | |
221 | ||
222 | error = create_by_name(name, mode, parent, &dentry); | |
223 | if (error) { | |
224 | dentry = ERR_PTR(error); | |
225 | simple_release_fs(&mount, &mount_count); | |
226 | goto exit; | |
227 | } | |
228 | ||
229 | if (dentry->d_inode) { | |
230 | if (fops) | |
231 | dentry->d_inode->i_fop = fops; | |
232 | if (data) | |
8e18e294 | 233 | dentry->d_inode->i_private = data; |
b67dbf9d GK |
234 | } |
235 | exit: | |
236 | return dentry; | |
237 | } | |
238 | EXPORT_SYMBOL_GPL(securityfs_create_file); | |
239 | ||
240 | /** | |
241 | * securityfs_create_dir - create a directory in the securityfs filesystem | |
242 | * | |
243 | * @name: a pointer to a string containing the name of the directory to | |
244 | * create. | |
245 | * @parent: a pointer to the parent dentry for this file. This should be a | |
3f23d815 | 246 | * directory dentry if set. If this parameter is %NULL, then the |
b67dbf9d GK |
247 | * directory will be created in the root of the securityfs filesystem. |
248 | * | |
3f23d815 | 249 | * This function creates a directory in securityfs with the given @name. |
b67dbf9d | 250 | * |
3f23d815 | 251 | * This function returns a pointer to a dentry if it succeeds. This |
b67dbf9d GK |
252 | * pointer must be passed to the securityfs_remove() function when the file is |
253 | * to be removed (no automatic cleanup happens if your module is unloaded, | |
3f23d815 | 254 | * you are responsible here). If an error occurs, %NULL will be returned. |
b67dbf9d | 255 | * |
3f23d815 | 256 | * If securityfs is not enabled in the kernel, the value %-ENODEV is |
b67dbf9d | 257 | * returned. It is not wise to check for this value, but rather, check for |
3f23d815 | 258 | * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling |
b67dbf9d GK |
259 | * code. |
260 | */ | |
261 | struct dentry *securityfs_create_dir(const char *name, struct dentry *parent) | |
262 | { | |
263 | return securityfs_create_file(name, | |
264 | S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO, | |
265 | parent, NULL, NULL); | |
266 | } | |
267 | EXPORT_SYMBOL_GPL(securityfs_create_dir); | |
268 | ||
269 | /** | |
270 | * securityfs_remove - removes a file or directory from the securityfs filesystem | |
271 | * | |
3f23d815 | 272 | * @dentry: a pointer to a the dentry of the file or directory to be removed. |
b67dbf9d GK |
273 | * |
274 | * This function removes a file or directory in securityfs that was previously | |
275 | * created with a call to another securityfs function (like | |
276 | * securityfs_create_file() or variants thereof.) | |
277 | * | |
278 | * This function is required to be called in order for the file to be | |
3f23d815 RD |
279 | * removed. No automatic cleanup of files will happen when a module is |
280 | * removed; you are responsible here. | |
b67dbf9d GK |
281 | */ |
282 | void securityfs_remove(struct dentry *dentry) | |
283 | { | |
284 | struct dentry *parent; | |
285 | ||
d93e4c94 | 286 | if (!dentry || IS_ERR(dentry)) |
b67dbf9d GK |
287 | return; |
288 | ||
289 | parent = dentry->d_parent; | |
290 | if (!parent || !parent->d_inode) | |
291 | return; | |
292 | ||
1b1dcc1b | 293 | mutex_lock(&parent->d_inode->i_mutex); |
b67dbf9d GK |
294 | if (positive(dentry)) { |
295 | if (dentry->d_inode) { | |
296 | if (S_ISDIR(dentry->d_inode->i_mode)) | |
297 | simple_rmdir(parent->d_inode, dentry); | |
298 | else | |
299 | simple_unlink(parent->d_inode, dentry); | |
300 | dput(dentry); | |
301 | } | |
302 | } | |
1b1dcc1b | 303 | mutex_unlock(&parent->d_inode->i_mutex); |
b67dbf9d GK |
304 | simple_release_fs(&mount, &mount_count); |
305 | } | |
306 | EXPORT_SYMBOL_GPL(securityfs_remove); | |
307 | ||
69d8e138 | 308 | static struct kobject *security_kobj; |
b67dbf9d GK |
309 | |
310 | static int __init securityfs_init(void) | |
311 | { | |
312 | int retval; | |
313 | ||
0ff21e46 | 314 | security_kobj = kobject_create_and_add("security", kernel_kobj); |
69d8e138 GKH |
315 | if (!security_kobj) |
316 | return -EINVAL; | |
b67dbf9d GK |
317 | |
318 | retval = register_filesystem(&fs_type); | |
319 | if (retval) | |
78a2d906 | 320 | kobject_put(security_kobj); |
b67dbf9d GK |
321 | return retval; |
322 | } | |
323 | ||
b67dbf9d | 324 | core_initcall(securityfs_init); |
b67dbf9d GK |
325 | MODULE_LICENSE("GPL"); |
326 |