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b67dbf9d GKH |
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 */ | |
1072bd67 PG |
16 | #include <linux/sysfs.h> |
17 | #include <linux/kobject.h> | |
b67dbf9d GKH |
18 | #include <linux/fs.h> |
19 | #include <linux/mount.h> | |
20 | #include <linux/pagemap.h> | |
21 | #include <linux/init.h> | |
22 | #include <linux/namei.h> | |
23 | #include <linux/security.h> | |
d69dece5 | 24 | #include <linux/lsm_hooks.h> |
92562927 | 25 | #include <linux/magic.h> |
b67dbf9d GKH |
26 | |
27 | static struct vfsmount *mount; | |
28 | static int mount_count; | |
29 | ||
6623ec7c JJ |
30 | static void securityfs_evict_inode(struct inode *inode) |
31 | { | |
32 | truncate_inode_pages_final(&inode->i_data); | |
33 | clear_inode(inode); | |
34 | if (S_ISLNK(inode->i_mode)) | |
35 | kfree(inode->i_link); | |
36 | } | |
37 | ||
38 | static const struct super_operations securityfs_super_operations = { | |
39 | .statfs = simple_statfs, | |
40 | .evict_inode = securityfs_evict_inode, | |
41 | }; | |
42 | ||
b67dbf9d GKH |
43 | static int fill_super(struct super_block *sb, void *data, int silent) |
44 | { | |
cda37124 | 45 | static const struct tree_descr files[] = {{""}}; |
6623ec7c JJ |
46 | int error; |
47 | ||
48 | error = simple_fill_super(sb, SECURITYFS_MAGIC, files); | |
49 | if (error) | |
50 | return error; | |
51 | ||
52 | sb->s_op = &securityfs_super_operations; | |
b67dbf9d | 53 | |
6623ec7c | 54 | return 0; |
b67dbf9d GKH |
55 | } |
56 | ||
fc14f2fe | 57 | static struct dentry *get_sb(struct file_system_type *fs_type, |
454e2398 | 58 | int flags, const char *dev_name, |
fc14f2fe | 59 | void *data) |
b67dbf9d | 60 | { |
fc14f2fe | 61 | return mount_single(fs_type, flags, data, fill_super); |
b67dbf9d GKH |
62 | } |
63 | ||
64 | static struct file_system_type fs_type = { | |
65 | .owner = THIS_MODULE, | |
66 | .name = "securityfs", | |
fc14f2fe | 67 | .mount = get_sb, |
b67dbf9d GKH |
68 | .kill_sb = kill_litter_super, |
69 | }; | |
70 | ||
b67dbf9d | 71 | /** |
6623ec7c | 72 | * securityfs_create_dentry - create a dentry in the securityfs filesystem |
b67dbf9d GKH |
73 | * |
74 | * @name: a pointer to a string containing the name of the file to create. | |
75 | * @mode: the permission that the file should have | |
76 | * @parent: a pointer to the parent dentry for this file. This should be a | |
3f23d815 | 77 | * directory dentry if set. If this parameter is %NULL, then the |
b67dbf9d GKH |
78 | * file will be created in the root of the securityfs filesystem. |
79 | * @data: a pointer to something that the caller will want to get to later | |
8e18e294 | 80 | * on. The inode.i_private pointer will point to this value on |
b67dbf9d GKH |
81 | * the open() call. |
82 | * @fops: a pointer to a struct file_operations that should be used for | |
83 | * this file. | |
6623ec7c JJ |
84 | * @iops: a point to a struct of inode_operations that should be used for |
85 | * this file/dir | |
b67dbf9d | 86 | * |
6623ec7c JJ |
87 | * This is the basic "create a file/dir/symlink" function for |
88 | * securityfs. It allows for a wide range of flexibility in creating | |
89 | * a file, or a directory (if you want to create a directory, the | |
90 | * securityfs_create_dir() function is recommended to be used | |
91 | * instead). | |
b67dbf9d | 92 | * |
3f23d815 | 93 | * This function returns a pointer to a dentry if it succeeds. This |
6623ec7c JJ |
94 | * pointer must be passed to the securityfs_remove() function when the |
95 | * file is to be removed (no automatic cleanup happens if your module | |
96 | * is unloaded, you are responsible here). If an error occurs, the | |
97 | * function will return the error value (via ERR_PTR). | |
b67dbf9d | 98 | * |
3f23d815 | 99 | * If securityfs is not enabled in the kernel, the value %-ENODEV is |
faa3aad7 | 100 | * returned. |
b67dbf9d | 101 | */ |
6623ec7c JJ |
102 | static struct dentry *securityfs_create_dentry(const char *name, umode_t mode, |
103 | struct dentry *parent, void *data, | |
104 | const struct file_operations *fops, | |
105 | const struct inode_operations *iops) | |
b67dbf9d | 106 | { |
3e25eb9c | 107 | struct dentry *dentry; |
3e25eb9c | 108 | struct inode *dir, *inode; |
b67dbf9d GKH |
109 | int error; |
110 | ||
6623ec7c | 111 | if (!(mode & S_IFMT)) |
3e25eb9c | 112 | mode = (mode & S_IALLUGO) | S_IFREG; |
3e25eb9c | 113 | |
b67dbf9d GKH |
114 | pr_debug("securityfs: creating file '%s'\n",name); |
115 | ||
1f5ce9e9 | 116 | error = simple_pin_fs(&fs_type, &mount, &mount_count); |
3e25eb9c AV |
117 | if (error) |
118 | return ERR_PTR(error); | |
119 | ||
120 | if (!parent) | |
121 | parent = mount->mnt_root; | |
122 | ||
ce0b16dd | 123 | dir = d_inode(parent); |
3e25eb9c | 124 | |
5955102c | 125 | inode_lock(dir); |
3e25eb9c AV |
126 | dentry = lookup_one_len(name, parent, strlen(name)); |
127 | if (IS_ERR(dentry)) | |
128 | goto out; | |
129 | ||
ce0b16dd | 130 | if (d_really_is_positive(dentry)) { |
3e25eb9c AV |
131 | error = -EEXIST; |
132 | goto out1; | |
b67dbf9d GKH |
133 | } |
134 | ||
3e25eb9c AV |
135 | inode = new_inode(dir->i_sb); |
136 | if (!inode) { | |
137 | error = -ENOMEM; | |
138 | goto out1; | |
b67dbf9d GKH |
139 | } |
140 | ||
3e25eb9c AV |
141 | inode->i_ino = get_next_ino(); |
142 | inode->i_mode = mode; | |
078cd827 | 143 | inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); |
3e25eb9c | 144 | inode->i_private = data; |
6623ec7c | 145 | if (S_ISDIR(mode)) { |
3e25eb9c AV |
146 | inode->i_op = &simple_dir_inode_operations; |
147 | inode->i_fop = &simple_dir_operations; | |
148 | inc_nlink(inode); | |
149 | inc_nlink(dir); | |
6623ec7c JJ |
150 | } else if (S_ISLNK(mode)) { |
151 | inode->i_op = iops ? iops : &simple_symlink_inode_operations; | |
152 | inode->i_link = data; | |
3e25eb9c AV |
153 | } else { |
154 | inode->i_fop = fops; | |
b67dbf9d | 155 | } |
3e25eb9c AV |
156 | d_instantiate(dentry, inode); |
157 | dget(dentry); | |
5955102c | 158 | inode_unlock(dir); |
3e25eb9c AV |
159 | return dentry; |
160 | ||
161 | out1: | |
162 | dput(dentry); | |
163 | dentry = ERR_PTR(error); | |
164 | out: | |
5955102c | 165 | inode_unlock(dir); |
3e25eb9c | 166 | simple_release_fs(&mount, &mount_count); |
b67dbf9d GKH |
167 | return dentry; |
168 | } | |
6623ec7c JJ |
169 | |
170 | /** | |
171 | * securityfs_create_file - create a file in the securityfs filesystem | |
172 | * | |
173 | * @name: a pointer to a string containing the name of the file to create. | |
174 | * @mode: the permission that the file should have | |
175 | * @parent: a pointer to the parent dentry for this file. This should be a | |
176 | * directory dentry if set. If this parameter is %NULL, then the | |
177 | * file will be created in the root of the securityfs filesystem. | |
178 | * @data: a pointer to something that the caller will want to get to later | |
179 | * on. The inode.i_private pointer will point to this value on | |
180 | * the open() call. | |
181 | * @fops: a pointer to a struct file_operations that should be used for | |
182 | * this file. | |
183 | * | |
184 | * This function creates a file in securityfs with the given @name. | |
185 | * | |
186 | * This function returns a pointer to a dentry if it succeeds. This | |
187 | * pointer must be passed to the securityfs_remove() function when the file is | |
188 | * to be removed (no automatic cleanup happens if your module is unloaded, | |
189 | * you are responsible here). If an error occurs, the function will return | |
190 | * the error value (via ERR_PTR). | |
191 | * | |
192 | * If securityfs is not enabled in the kernel, the value %-ENODEV is | |
193 | * returned. | |
194 | */ | |
195 | struct dentry *securityfs_create_file(const char *name, umode_t mode, | |
196 | struct dentry *parent, void *data, | |
197 | const struct file_operations *fops) | |
198 | { | |
199 | return securityfs_create_dentry(name, mode, parent, data, fops, NULL); | |
200 | } | |
b67dbf9d GKH |
201 | EXPORT_SYMBOL_GPL(securityfs_create_file); |
202 | ||
203 | /** | |
204 | * securityfs_create_dir - create a directory in the securityfs filesystem | |
205 | * | |
206 | * @name: a pointer to a string containing the name of the directory to | |
207 | * create. | |
208 | * @parent: a pointer to the parent dentry for this file. This should be a | |
3f23d815 | 209 | * directory dentry if set. If this parameter is %NULL, then the |
b67dbf9d GKH |
210 | * directory will be created in the root of the securityfs filesystem. |
211 | * | |
3f23d815 | 212 | * This function creates a directory in securityfs with the given @name. |
b67dbf9d | 213 | * |
3f23d815 | 214 | * This function returns a pointer to a dentry if it succeeds. This |
b67dbf9d GKH |
215 | * pointer must be passed to the securityfs_remove() function when the file is |
216 | * to be removed (no automatic cleanup happens if your module is unloaded, | |
1b460651 LG |
217 | * you are responsible here). If an error occurs, the function will return |
218 | * the error value (via ERR_PTR). | |
b67dbf9d | 219 | * |
3f23d815 | 220 | * If securityfs is not enabled in the kernel, the value %-ENODEV is |
1b460651 | 221 | * returned. |
b67dbf9d GKH |
222 | */ |
223 | struct dentry *securityfs_create_dir(const char *name, struct dentry *parent) | |
224 | { | |
6623ec7c | 225 | return securityfs_create_file(name, S_IFDIR | 0755, parent, NULL, NULL); |
b67dbf9d GKH |
226 | } |
227 | EXPORT_SYMBOL_GPL(securityfs_create_dir); | |
228 | ||
6623ec7c JJ |
229 | /** |
230 | * securityfs_create_symlink - create a symlink in the securityfs filesystem | |
231 | * | |
232 | * @name: a pointer to a string containing the name of the symlink to | |
233 | * create. | |
234 | * @parent: a pointer to the parent dentry for the symlink. This should be a | |
235 | * directory dentry if set. If this parameter is %NULL, then the | |
236 | * directory will be created in the root of the securityfs filesystem. | |
237 | * @target: a pointer to a string containing the name of the symlink's target. | |
238 | * If this parameter is %NULL, then the @iops parameter needs to be | |
239 | * setup to handle .readlink and .get_link inode_operations. | |
240 | * @iops: a pointer to the struct inode_operations to use for the symlink. If | |
241 | * this parameter is %NULL, then the default simple_symlink_inode | |
242 | * operations will be used. | |
243 | * | |
244 | * This function creates a symlink in securityfs with the given @name. | |
245 | * | |
246 | * This function returns a pointer to a dentry if it succeeds. This | |
247 | * pointer must be passed to the securityfs_remove() function when the file is | |
248 | * to be removed (no automatic cleanup happens if your module is unloaded, | |
249 | * you are responsible here). If an error occurs, the function will return | |
250 | * the error value (via ERR_PTR). | |
251 | * | |
252 | * If securityfs is not enabled in the kernel, the value %-ENODEV is | |
253 | * returned. | |
254 | */ | |
255 | struct dentry *securityfs_create_symlink(const char *name, | |
256 | struct dentry *parent, | |
257 | const char *target, | |
258 | const struct inode_operations *iops) | |
259 | { | |
260 | struct dentry *dent; | |
261 | char *link = NULL; | |
262 | ||
263 | if (target) { | |
264 | link = kstrdup(target, GFP_KERNEL); | |
265 | if (!link) | |
266 | return ERR_PTR(-ENOMEM); | |
267 | } | |
268 | dent = securityfs_create_dentry(name, S_IFLNK | 0444, parent, | |
269 | link, NULL, iops); | |
270 | if (IS_ERR(dent)) | |
271 | kfree(link); | |
272 | ||
273 | return dent; | |
274 | } | |
275 | EXPORT_SYMBOL_GPL(securityfs_create_symlink); | |
276 | ||
b67dbf9d GKH |
277 | /** |
278 | * securityfs_remove - removes a file or directory from the securityfs filesystem | |
279 | * | |
3f23d815 | 280 | * @dentry: a pointer to a the dentry of the file or directory to be removed. |
b67dbf9d GKH |
281 | * |
282 | * This function removes a file or directory in securityfs that was previously | |
283 | * created with a call to another securityfs function (like | |
284 | * securityfs_create_file() or variants thereof.) | |
285 | * | |
286 | * This function is required to be called in order for the file to be | |
3f23d815 RD |
287 | * removed. No automatic cleanup of files will happen when a module is |
288 | * removed; you are responsible here. | |
b67dbf9d GKH |
289 | */ |
290 | void securityfs_remove(struct dentry *dentry) | |
291 | { | |
4093d306 | 292 | struct inode *dir; |
b67dbf9d | 293 | |
d93e4c94 | 294 | if (!dentry || IS_ERR(dentry)) |
b67dbf9d GKH |
295 | return; |
296 | ||
4093d306 AV |
297 | dir = d_inode(dentry->d_parent); |
298 | inode_lock(dir); | |
dc3f4198 AV |
299 | if (simple_positive(dentry)) { |
300 | if (d_is_dir(dentry)) | |
4093d306 | 301 | simple_rmdir(dir, dentry); |
dc3f4198 | 302 | else |
4093d306 | 303 | simple_unlink(dir, dentry); |
dc3f4198 | 304 | dput(dentry); |
b67dbf9d | 305 | } |
4093d306 | 306 | inode_unlock(dir); |
b67dbf9d GKH |
307 | simple_release_fs(&mount, &mount_count); |
308 | } | |
309 | EXPORT_SYMBOL_GPL(securityfs_remove); | |
310 | ||
d69dece5 CS |
311 | #ifdef CONFIG_SECURITY |
312 | static struct dentry *lsm_dentry; | |
313 | static ssize_t lsm_read(struct file *filp, char __user *buf, size_t count, | |
314 | loff_t *ppos) | |
315 | { | |
316 | return simple_read_from_buffer(buf, count, ppos, lsm_names, | |
317 | strlen(lsm_names)); | |
318 | } | |
319 | ||
320 | static const struct file_operations lsm_ops = { | |
321 | .read = lsm_read, | |
322 | .llseek = generic_file_llseek, | |
323 | }; | |
324 | #endif | |
325 | ||
b67dbf9d GKH |
326 | static int __init securityfs_init(void) |
327 | { | |
328 | int retval; | |
329 | ||
f9bb4882 EB |
330 | retval = sysfs_create_mount_point(kernel_kobj, "security"); |
331 | if (retval) | |
332 | return retval; | |
b67dbf9d GKH |
333 | |
334 | retval = register_filesystem(&fs_type); | |
d69dece5 | 335 | if (retval) { |
f9bb4882 | 336 | sysfs_remove_mount_point(kernel_kobj, "security"); |
d69dece5 CS |
337 | return retval; |
338 | } | |
339 | #ifdef CONFIG_SECURITY | |
340 | lsm_dentry = securityfs_create_file("lsm", 0444, NULL, NULL, | |
341 | &lsm_ops); | |
342 | #endif | |
343 | return 0; | |
b67dbf9d | 344 | } |
b67dbf9d | 345 | core_initcall(securityfs_init); |