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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> | |
23 | ||
24 | #define SECURITYFS_MAGIC 0x73636673 | |
25 | ||
26 | static struct vfsmount *mount; | |
27 | static int mount_count; | |
28 | ||
29 | /* | |
30 | * TODO: | |
31 | * I think I can get rid of these default_file_ops, but not quite sure... | |
32 | */ | |
33 | static ssize_t default_read_file(struct file *file, char __user *buf, | |
34 | size_t count, loff_t *ppos) | |
35 | { | |
36 | return 0; | |
37 | } | |
38 | ||
39 | static ssize_t default_write_file(struct file *file, const char __user *buf, | |
40 | size_t count, loff_t *ppos) | |
41 | { | |
42 | return count; | |
43 | } | |
44 | ||
45 | static int default_open(struct inode *inode, struct file *file) | |
46 | { | |
47 | if (inode->u.generic_ip) | |
48 | file->private_data = inode->u.generic_ip; | |
49 | ||
50 | return 0; | |
51 | } | |
52 | ||
53 | static struct file_operations default_file_ops = { | |
54 | .read = default_read_file, | |
55 | .write = default_write_file, | |
56 | .open = default_open, | |
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; | |
65 | inode->i_uid = 0; | |
66 | inode->i_gid = 0; | |
67 | inode->i_blksize = PAGE_CACHE_SIZE; | |
68 | inode->i_blocks = 0; | |
69 | inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; | |
70 | switch (mode & S_IFMT) { | |
71 | default: | |
72 | init_special_inode(inode, mode, dev); | |
73 | break; | |
74 | case S_IFREG: | |
75 | inode->i_fop = &default_file_ops; | |
76 | break; | |
77 | case S_IFDIR: | |
78 | inode->i_op = &simple_dir_inode_operations; | |
79 | inode->i_fop = &simple_dir_operations; | |
80 | ||
81 | /* directory inodes start off with i_nlink == 2 (for "." entry) */ | |
82 | inode->i_nlink++; | |
83 | break; | |
84 | } | |
85 | } | |
86 | return inode; | |
87 | } | |
88 | ||
89 | /* SMP-safe */ | |
90 | static int mknod(struct inode *dir, struct dentry *dentry, | |
91 | int mode, dev_t dev) | |
92 | { | |
93 | struct inode *inode; | |
94 | int error = -EPERM; | |
95 | ||
96 | if (dentry->d_inode) | |
97 | return -EEXIST; | |
98 | ||
99 | inode = get_inode(dir->i_sb, mode, dev); | |
100 | if (inode) { | |
101 | d_instantiate(dentry, inode); | |
102 | dget(dentry); | |
103 | error = 0; | |
104 | } | |
105 | return error; | |
106 | } | |
107 | ||
108 | static int mkdir(struct inode *dir, struct dentry *dentry, int mode) | |
109 | { | |
110 | int res; | |
111 | ||
112 | mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR; | |
113 | res = mknod(dir, dentry, mode, 0); | |
114 | if (!res) | |
115 | dir->i_nlink++; | |
116 | return res; | |
117 | } | |
118 | ||
119 | static int create(struct inode *dir, struct dentry *dentry, int mode) | |
120 | { | |
121 | mode = (mode & S_IALLUGO) | S_IFREG; | |
122 | return mknod(dir, dentry, mode, 0); | |
123 | } | |
124 | ||
125 | static inline int positive(struct dentry *dentry) | |
126 | { | |
127 | return dentry->d_inode && !d_unhashed(dentry); | |
128 | } | |
129 | ||
130 | static int fill_super(struct super_block *sb, void *data, int silent) | |
131 | { | |
132 | static struct tree_descr files[] = {{""}}; | |
133 | ||
134 | return simple_fill_super(sb, SECURITYFS_MAGIC, files); | |
135 | } | |
136 | ||
454e2398 DH |
137 | static int get_sb(struct file_system_type *fs_type, |
138 | int flags, const char *dev_name, | |
139 | void *data, struct vfsmount *mnt) | |
b67dbf9d | 140 | { |
454e2398 | 141 | return get_sb_single(fs_type, flags, data, fill_super, mnt); |
b67dbf9d GK |
142 | } |
143 | ||
144 | static struct file_system_type fs_type = { | |
145 | .owner = THIS_MODULE, | |
146 | .name = "securityfs", | |
147 | .get_sb = get_sb, | |
148 | .kill_sb = kill_litter_super, | |
149 | }; | |
150 | ||
151 | static int create_by_name(const char *name, mode_t mode, | |
152 | struct dentry *parent, | |
153 | struct dentry **dentry) | |
154 | { | |
155 | int error = 0; | |
156 | ||
157 | *dentry = NULL; | |
158 | ||
159 | /* If the parent is not specified, we create it in the root. | |
160 | * We need the root dentry to do this, which is in the super | |
161 | * block. A pointer to that is in the struct vfsmount that we | |
162 | * have around. | |
163 | */ | |
164 | if (!parent ) { | |
165 | if (mount && mount->mnt_sb) { | |
166 | parent = mount->mnt_sb->s_root; | |
167 | } | |
168 | } | |
169 | if (!parent) { | |
170 | pr_debug("securityfs: Ah! can not find a parent!\n"); | |
171 | return -EFAULT; | |
172 | } | |
173 | ||
1b1dcc1b | 174 | mutex_lock(&parent->d_inode->i_mutex); |
b67dbf9d GK |
175 | *dentry = lookup_one_len(name, parent, strlen(name)); |
176 | if (!IS_ERR(dentry)) { | |
177 | if ((mode & S_IFMT) == S_IFDIR) | |
178 | error = mkdir(parent->d_inode, *dentry, mode); | |
179 | else | |
180 | error = create(parent->d_inode, *dentry, mode); | |
181 | } else | |
182 | error = PTR_ERR(dentry); | |
1b1dcc1b | 183 | mutex_unlock(&parent->d_inode->i_mutex); |
b67dbf9d GK |
184 | |
185 | return error; | |
186 | } | |
187 | ||
188 | /** | |
189 | * securityfs_create_file - create a file in the securityfs filesystem | |
190 | * | |
191 | * @name: a pointer to a string containing the name of the file to create. | |
192 | * @mode: the permission that the file should have | |
193 | * @parent: a pointer to the parent dentry for this file. This should be a | |
194 | * directory dentry if set. If this paramater is NULL, then the | |
195 | * file will be created in the root of the securityfs filesystem. | |
196 | * @data: a pointer to something that the caller will want to get to later | |
197 | * on. The inode.u.generic_ip pointer will point to this value on | |
198 | * the open() call. | |
199 | * @fops: a pointer to a struct file_operations that should be used for | |
200 | * this file. | |
201 | * | |
202 | * This is the basic "create a file" function for securityfs. It allows for a | |
203 | * wide range of flexibility in createing a file, or a directory (if you | |
204 | * want to create a directory, the securityfs_create_dir() function is | |
205 | * recommended to be used instead.) | |
206 | * | |
207 | * This function will return a pointer to a dentry if it succeeds. This | |
208 | * pointer must be passed to the securityfs_remove() function when the file is | |
209 | * to be removed (no automatic cleanup happens if your module is unloaded, | |
210 | * you are responsible here.) If an error occurs, NULL will be returned. | |
211 | * | |
212 | * If securityfs is not enabled in the kernel, the value -ENODEV will be | |
213 | * returned. It is not wise to check for this value, but rather, check for | |
214 | * NULL or !NULL instead as to eliminate the need for #ifdef in the calling | |
215 | * code. | |
216 | */ | |
217 | struct dentry *securityfs_create_file(const char *name, mode_t mode, | |
218 | struct dentry *parent, void *data, | |
219 | struct file_operations *fops) | |
220 | { | |
221 | struct dentry *dentry = NULL; | |
222 | int error; | |
223 | ||
224 | pr_debug("securityfs: creating file '%s'\n",name); | |
225 | ||
1f5ce9e9 | 226 | error = simple_pin_fs(&fs_type, &mount, &mount_count); |
b67dbf9d GK |
227 | if (error) { |
228 | dentry = ERR_PTR(error); | |
229 | goto exit; | |
230 | } | |
231 | ||
232 | error = create_by_name(name, mode, parent, &dentry); | |
233 | if (error) { | |
234 | dentry = ERR_PTR(error); | |
235 | simple_release_fs(&mount, &mount_count); | |
236 | goto exit; | |
237 | } | |
238 | ||
239 | if (dentry->d_inode) { | |
240 | if (fops) | |
241 | dentry->d_inode->i_fop = fops; | |
242 | if (data) | |
243 | dentry->d_inode->u.generic_ip = data; | |
244 | } | |
245 | exit: | |
246 | return dentry; | |
247 | } | |
248 | EXPORT_SYMBOL_GPL(securityfs_create_file); | |
249 | ||
250 | /** | |
251 | * securityfs_create_dir - create a directory in the securityfs filesystem | |
252 | * | |
253 | * @name: a pointer to a string containing the name of the directory to | |
254 | * create. | |
255 | * @parent: a pointer to the parent dentry for this file. This should be a | |
256 | * directory dentry if set. If this paramater is NULL, then the | |
257 | * directory will be created in the root of the securityfs filesystem. | |
258 | * | |
259 | * This function creates a directory in securityfs with the given name. | |
260 | * | |
261 | * This function will return a pointer to a dentry if it succeeds. This | |
262 | * pointer must be passed to the securityfs_remove() function when the file is | |
263 | * to be removed (no automatic cleanup happens if your module is unloaded, | |
264 | * you are responsible here.) If an error occurs, NULL will be returned. | |
265 | * | |
266 | * If securityfs is not enabled in the kernel, the value -ENODEV will be | |
267 | * returned. It is not wise to check for this value, but rather, check for | |
268 | * NULL or !NULL instead as to eliminate the need for #ifdef in the calling | |
269 | * code. | |
270 | */ | |
271 | struct dentry *securityfs_create_dir(const char *name, struct dentry *parent) | |
272 | { | |
273 | return securityfs_create_file(name, | |
274 | S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO, | |
275 | parent, NULL, NULL); | |
276 | } | |
277 | EXPORT_SYMBOL_GPL(securityfs_create_dir); | |
278 | ||
279 | /** | |
280 | * securityfs_remove - removes a file or directory from the securityfs filesystem | |
281 | * | |
282 | * @dentry: a pointer to a the dentry of the file or directory to be | |
283 | * removed. | |
284 | * | |
285 | * This function removes a file or directory in securityfs that was previously | |
286 | * created with a call to another securityfs function (like | |
287 | * securityfs_create_file() or variants thereof.) | |
288 | * | |
289 | * This function is required to be called in order for the file to be | |
290 | * removed, no automatic cleanup of files will happen when a module is | |
291 | * removed, you are responsible here. | |
292 | */ | |
293 | void securityfs_remove(struct dentry *dentry) | |
294 | { | |
295 | struct dentry *parent; | |
296 | ||
297 | if (!dentry) | |
298 | return; | |
299 | ||
300 | parent = dentry->d_parent; | |
301 | if (!parent || !parent->d_inode) | |
302 | return; | |
303 | ||
1b1dcc1b | 304 | mutex_lock(&parent->d_inode->i_mutex); |
b67dbf9d GK |
305 | if (positive(dentry)) { |
306 | if (dentry->d_inode) { | |
307 | if (S_ISDIR(dentry->d_inode->i_mode)) | |
308 | simple_rmdir(parent->d_inode, dentry); | |
309 | else | |
310 | simple_unlink(parent->d_inode, dentry); | |
311 | dput(dentry); | |
312 | } | |
313 | } | |
1b1dcc1b | 314 | mutex_unlock(&parent->d_inode->i_mutex); |
b67dbf9d GK |
315 | simple_release_fs(&mount, &mount_count); |
316 | } | |
317 | EXPORT_SYMBOL_GPL(securityfs_remove); | |
318 | ||
319 | static decl_subsys(security, NULL, NULL); | |
320 | ||
321 | static int __init securityfs_init(void) | |
322 | { | |
323 | int retval; | |
324 | ||
325 | kset_set_kset_s(&security_subsys, kernel_subsys); | |
326 | retval = subsystem_register(&security_subsys); | |
327 | if (retval) | |
328 | return retval; | |
329 | ||
330 | retval = register_filesystem(&fs_type); | |
331 | if (retval) | |
332 | subsystem_unregister(&security_subsys); | |
333 | return retval; | |
334 | } | |
335 | ||
336 | static void __exit securityfs_exit(void) | |
337 | { | |
338 | simple_release_fs(&mount, &mount_count); | |
339 | unregister_filesystem(&fs_type); | |
340 | subsystem_unregister(&security_subsys); | |
341 | } | |
342 | ||
343 | core_initcall(securityfs_init); | |
344 | module_exit(securityfs_exit); | |
345 | MODULE_LICENSE("GPL"); | |
346 |