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d2912cb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
b67dbf9d GK |
2 | /* |
3 | * inode.c - securityfs | |
4 | * | |
5 | * Copyright (C) 2005 Greg Kroah-Hartman <gregkh@suse.de> | |
6 | * | |
b67dbf9d GK |
7 | * Based on fs/debugfs/inode.c which had the following copyright notice: |
8 | * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com> | |
9 | * Copyright (C) 2004 IBM Inc. | |
10 | */ | |
11 | ||
12 | /* #define DEBUG */ | |
1072bd67 PG |
13 | #include <linux/sysfs.h> |
14 | #include <linux/kobject.h> | |
b67dbf9d GK |
15 | #include <linux/fs.h> |
16 | #include <linux/mount.h> | |
17 | #include <linux/pagemap.h> | |
18 | #include <linux/init.h> | |
19 | #include <linux/namei.h> | |
20 | #include <linux/security.h> | |
d69dece5 | 21 | #include <linux/lsm_hooks.h> |
92562927 | 22 | #include <linux/magic.h> |
b67dbf9d GK |
23 | |
24 | static struct vfsmount *mount; | |
25 | static int mount_count; | |
26 | ||
f614ee1e | 27 | static void securityfs_free_inode(struct inode *inode) |
6623ec7c | 28 | { |
6623ec7c JJ |
29 | if (S_ISLNK(inode->i_mode)) |
30 | kfree(inode->i_link); | |
46c87441 AV |
31 | free_inode_nonrcu(inode); |
32 | } | |
33 | ||
6623ec7c JJ |
34 | static const struct super_operations securityfs_super_operations = { |
35 | .statfs = simple_statfs, | |
f614ee1e | 36 | .free_inode = securityfs_free_inode, |
6623ec7c JJ |
37 | }; |
38 | ||
b67dbf9d GK |
39 | static int fill_super(struct super_block *sb, void *data, int silent) |
40 | { | |
cda37124 | 41 | static const struct tree_descr files[] = {{""}}; |
6623ec7c JJ |
42 | int error; |
43 | ||
44 | error = simple_fill_super(sb, SECURITYFS_MAGIC, files); | |
45 | if (error) | |
46 | return error; | |
47 | ||
48 | sb->s_op = &securityfs_super_operations; | |
b67dbf9d | 49 | |
6623ec7c | 50 | return 0; |
b67dbf9d GK |
51 | } |
52 | ||
fc14f2fe | 53 | static struct dentry *get_sb(struct file_system_type *fs_type, |
454e2398 | 54 | int flags, const char *dev_name, |
fc14f2fe | 55 | void *data) |
b67dbf9d | 56 | { |
fc14f2fe | 57 | return mount_single(fs_type, flags, data, fill_super); |
b67dbf9d GK |
58 | } |
59 | ||
60 | static struct file_system_type fs_type = { | |
61 | .owner = THIS_MODULE, | |
62 | .name = "securityfs", | |
fc14f2fe | 63 | .mount = get_sb, |
b67dbf9d GK |
64 | .kill_sb = kill_litter_super, |
65 | }; | |
66 | ||
b67dbf9d | 67 | /** |
6623ec7c | 68 | * securityfs_create_dentry - create a dentry in the securityfs filesystem |
b67dbf9d GK |
69 | * |
70 | * @name: a pointer to a string containing the name of the file to create. | |
71 | * @mode: the permission that the file should have | |
72 | * @parent: a pointer to the parent dentry for this file. This should be a | |
3f23d815 | 73 | * directory dentry if set. If this parameter is %NULL, then the |
b67dbf9d GK |
74 | * file will be created in the root of the securityfs filesystem. |
75 | * @data: a pointer to something that the caller will want to get to later | |
8e18e294 | 76 | * on. The inode.i_private pointer will point to this value on |
b67dbf9d GK |
77 | * the open() call. |
78 | * @fops: a pointer to a struct file_operations that should be used for | |
79 | * this file. | |
6623ec7c JJ |
80 | * @iops: a point to a struct of inode_operations that should be used for |
81 | * this file/dir | |
b67dbf9d | 82 | * |
6623ec7c JJ |
83 | * This is the basic "create a file/dir/symlink" function for |
84 | * securityfs. It allows for a wide range of flexibility in creating | |
85 | * a file, or a directory (if you want to create a directory, the | |
86 | * securityfs_create_dir() function is recommended to be used | |
87 | * instead). | |
b67dbf9d | 88 | * |
3f23d815 | 89 | * This function returns a pointer to a dentry if it succeeds. This |
6623ec7c JJ |
90 | * pointer must be passed to the securityfs_remove() function when the |
91 | * file is to be removed (no automatic cleanup happens if your module | |
92 | * is unloaded, you are responsible here). If an error occurs, the | |
93 | * function will return the error value (via ERR_PTR). | |
b67dbf9d | 94 | * |
3f23d815 | 95 | * If securityfs is not enabled in the kernel, the value %-ENODEV is |
faa3aad7 | 96 | * returned. |
b67dbf9d | 97 | */ |
6623ec7c JJ |
98 | static struct dentry *securityfs_create_dentry(const char *name, umode_t mode, |
99 | struct dentry *parent, void *data, | |
100 | const struct file_operations *fops, | |
101 | const struct inode_operations *iops) | |
b67dbf9d | 102 | { |
3e25eb9c | 103 | struct dentry *dentry; |
3e25eb9c | 104 | struct inode *dir, *inode; |
b67dbf9d GK |
105 | int error; |
106 | ||
6623ec7c | 107 | if (!(mode & S_IFMT)) |
3e25eb9c | 108 | mode = (mode & S_IALLUGO) | S_IFREG; |
3e25eb9c | 109 | |
b67dbf9d GK |
110 | pr_debug("securityfs: creating file '%s'\n",name); |
111 | ||
1f5ce9e9 | 112 | error = simple_pin_fs(&fs_type, &mount, &mount_count); |
3e25eb9c AV |
113 | if (error) |
114 | return ERR_PTR(error); | |
115 | ||
116 | if (!parent) | |
117 | parent = mount->mnt_root; | |
118 | ||
ce0b16dd | 119 | dir = d_inode(parent); |
3e25eb9c | 120 | |
5955102c | 121 | inode_lock(dir); |
3e25eb9c AV |
122 | dentry = lookup_one_len(name, parent, strlen(name)); |
123 | if (IS_ERR(dentry)) | |
124 | goto out; | |
125 | ||
ce0b16dd | 126 | if (d_really_is_positive(dentry)) { |
3e25eb9c AV |
127 | error = -EEXIST; |
128 | goto out1; | |
b67dbf9d GK |
129 | } |
130 | ||
3e25eb9c AV |
131 | inode = new_inode(dir->i_sb); |
132 | if (!inode) { | |
133 | error = -ENOMEM; | |
134 | goto out1; | |
b67dbf9d GK |
135 | } |
136 | ||
3e25eb9c AV |
137 | inode->i_ino = get_next_ino(); |
138 | inode->i_mode = mode; | |
078cd827 | 139 | inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); |
3e25eb9c | 140 | inode->i_private = data; |
6623ec7c | 141 | if (S_ISDIR(mode)) { |
3e25eb9c AV |
142 | inode->i_op = &simple_dir_inode_operations; |
143 | inode->i_fop = &simple_dir_operations; | |
144 | inc_nlink(inode); | |
145 | inc_nlink(dir); | |
6623ec7c JJ |
146 | } else if (S_ISLNK(mode)) { |
147 | inode->i_op = iops ? iops : &simple_symlink_inode_operations; | |
148 | inode->i_link = data; | |
3e25eb9c AV |
149 | } else { |
150 | inode->i_fop = fops; | |
b67dbf9d | 151 | } |
3e25eb9c AV |
152 | d_instantiate(dentry, inode); |
153 | dget(dentry); | |
5955102c | 154 | inode_unlock(dir); |
3e25eb9c AV |
155 | return dentry; |
156 | ||
157 | out1: | |
158 | dput(dentry); | |
159 | dentry = ERR_PTR(error); | |
160 | out: | |
5955102c | 161 | inode_unlock(dir); |
3e25eb9c | 162 | simple_release_fs(&mount, &mount_count); |
b67dbf9d GK |
163 | return dentry; |
164 | } | |
6623ec7c JJ |
165 | |
166 | /** | |
167 | * securityfs_create_file - create a file in the securityfs filesystem | |
168 | * | |
169 | * @name: a pointer to a string containing the name of the file to create. | |
170 | * @mode: the permission that the file should have | |
171 | * @parent: a pointer to the parent dentry for this file. This should be a | |
172 | * directory dentry if set. If this parameter is %NULL, then the | |
173 | * file will be created in the root of the securityfs filesystem. | |
174 | * @data: a pointer to something that the caller will want to get to later | |
175 | * on. The inode.i_private pointer will point to this value on | |
176 | * the open() call. | |
177 | * @fops: a pointer to a struct file_operations that should be used for | |
178 | * this file. | |
179 | * | |
180 | * This function creates a file in securityfs with the given @name. | |
181 | * | |
182 | * This function returns a pointer to a dentry if it succeeds. This | |
183 | * pointer must be passed to the securityfs_remove() function when the file is | |
184 | * to be removed (no automatic cleanup happens if your module is unloaded, | |
185 | * you are responsible here). If an error occurs, the function will return | |
186 | * the error value (via ERR_PTR). | |
187 | * | |
188 | * If securityfs is not enabled in the kernel, the value %-ENODEV is | |
189 | * returned. | |
190 | */ | |
191 | struct dentry *securityfs_create_file(const char *name, umode_t mode, | |
192 | struct dentry *parent, void *data, | |
193 | const struct file_operations *fops) | |
194 | { | |
195 | return securityfs_create_dentry(name, mode, parent, data, fops, NULL); | |
196 | } | |
b67dbf9d GK |
197 | EXPORT_SYMBOL_GPL(securityfs_create_file); |
198 | ||
199 | /** | |
200 | * securityfs_create_dir - create a directory in the securityfs filesystem | |
201 | * | |
202 | * @name: a pointer to a string containing the name of the directory to | |
203 | * create. | |
204 | * @parent: a pointer to the parent dentry for this file. This should be a | |
3f23d815 | 205 | * directory dentry if set. If this parameter is %NULL, then the |
b67dbf9d GK |
206 | * directory will be created in the root of the securityfs filesystem. |
207 | * | |
3f23d815 | 208 | * This function creates a directory in securityfs with the given @name. |
b67dbf9d | 209 | * |
3f23d815 | 210 | * This function returns a pointer to a dentry if it succeeds. This |
b67dbf9d GK |
211 | * pointer must be passed to the securityfs_remove() function when the file is |
212 | * to be removed (no automatic cleanup happens if your module is unloaded, | |
1b460651 LG |
213 | * you are responsible here). If an error occurs, the function will return |
214 | * the error value (via ERR_PTR). | |
b67dbf9d | 215 | * |
3f23d815 | 216 | * If securityfs is not enabled in the kernel, the value %-ENODEV is |
1b460651 | 217 | * returned. |
b67dbf9d GK |
218 | */ |
219 | struct dentry *securityfs_create_dir(const char *name, struct dentry *parent) | |
220 | { | |
6623ec7c | 221 | return securityfs_create_file(name, S_IFDIR | 0755, parent, NULL, NULL); |
b67dbf9d GK |
222 | } |
223 | EXPORT_SYMBOL_GPL(securityfs_create_dir); | |
224 | ||
6623ec7c JJ |
225 | /** |
226 | * securityfs_create_symlink - create a symlink in the securityfs filesystem | |
227 | * | |
228 | * @name: a pointer to a string containing the name of the symlink to | |
229 | * create. | |
230 | * @parent: a pointer to the parent dentry for the symlink. This should be a | |
231 | * directory dentry if set. If this parameter is %NULL, then the | |
232 | * directory will be created in the root of the securityfs filesystem. | |
233 | * @target: a pointer to a string containing the name of the symlink's target. | |
234 | * If this parameter is %NULL, then the @iops parameter needs to be | |
235 | * setup to handle .readlink and .get_link inode_operations. | |
236 | * @iops: a pointer to the struct inode_operations to use for the symlink. If | |
237 | * this parameter is %NULL, then the default simple_symlink_inode | |
238 | * operations will be used. | |
239 | * | |
240 | * This function creates a symlink in securityfs with the given @name. | |
241 | * | |
242 | * This function returns a pointer to a dentry if it succeeds. This | |
243 | * pointer must be passed to the securityfs_remove() function when the file is | |
244 | * to be removed (no automatic cleanup happens if your module is unloaded, | |
245 | * you are responsible here). If an error occurs, the function will return | |
246 | * the error value (via ERR_PTR). | |
247 | * | |
248 | * If securityfs is not enabled in the kernel, the value %-ENODEV is | |
249 | * returned. | |
250 | */ | |
251 | struct dentry *securityfs_create_symlink(const char *name, | |
252 | struct dentry *parent, | |
253 | const char *target, | |
254 | const struct inode_operations *iops) | |
255 | { | |
256 | struct dentry *dent; | |
257 | char *link = NULL; | |
258 | ||
259 | if (target) { | |
260 | link = kstrdup(target, GFP_KERNEL); | |
261 | if (!link) | |
262 | return ERR_PTR(-ENOMEM); | |
263 | } | |
264 | dent = securityfs_create_dentry(name, S_IFLNK | 0444, parent, | |
265 | link, NULL, iops); | |
266 | if (IS_ERR(dent)) | |
267 | kfree(link); | |
268 | ||
269 | return dent; | |
270 | } | |
271 | EXPORT_SYMBOL_GPL(securityfs_create_symlink); | |
272 | ||
b67dbf9d GK |
273 | /** |
274 | * securityfs_remove - removes a file or directory from the securityfs filesystem | |
275 | * | |
3f23d815 | 276 | * @dentry: a pointer to a the dentry of the file or directory to be removed. |
b67dbf9d GK |
277 | * |
278 | * This function removes a file or directory in securityfs that was previously | |
279 | * created with a call to another securityfs function (like | |
280 | * securityfs_create_file() or variants thereof.) | |
281 | * | |
282 | * This function is required to be called in order for the file to be | |
3f23d815 RD |
283 | * removed. No automatic cleanup of files will happen when a module is |
284 | * removed; you are responsible here. | |
b67dbf9d GK |
285 | */ |
286 | void securityfs_remove(struct dentry *dentry) | |
287 | { | |
4093d306 | 288 | struct inode *dir; |
b67dbf9d | 289 | |
d93e4c94 | 290 | if (!dentry || IS_ERR(dentry)) |
b67dbf9d GK |
291 | return; |
292 | ||
4093d306 AV |
293 | dir = d_inode(dentry->d_parent); |
294 | inode_lock(dir); | |
dc3f4198 AV |
295 | if (simple_positive(dentry)) { |
296 | if (d_is_dir(dentry)) | |
4093d306 | 297 | simple_rmdir(dir, dentry); |
dc3f4198 | 298 | else |
4093d306 | 299 | simple_unlink(dir, dentry); |
dc3f4198 | 300 | dput(dentry); |
b67dbf9d | 301 | } |
4093d306 | 302 | inode_unlock(dir); |
b67dbf9d GK |
303 | simple_release_fs(&mount, &mount_count); |
304 | } | |
305 | EXPORT_SYMBOL_GPL(securityfs_remove); | |
306 | ||
d69dece5 CS |
307 | #ifdef CONFIG_SECURITY |
308 | static struct dentry *lsm_dentry; | |
309 | static ssize_t lsm_read(struct file *filp, char __user *buf, size_t count, | |
310 | loff_t *ppos) | |
311 | { | |
312 | return simple_read_from_buffer(buf, count, ppos, lsm_names, | |
313 | strlen(lsm_names)); | |
314 | } | |
315 | ||
316 | static const struct file_operations lsm_ops = { | |
317 | .read = lsm_read, | |
318 | .llseek = generic_file_llseek, | |
319 | }; | |
320 | #endif | |
321 | ||
b67dbf9d GK |
322 | static int __init securityfs_init(void) |
323 | { | |
324 | int retval; | |
325 | ||
f9bb4882 EB |
326 | retval = sysfs_create_mount_point(kernel_kobj, "security"); |
327 | if (retval) | |
328 | return retval; | |
b67dbf9d GK |
329 | |
330 | retval = register_filesystem(&fs_type); | |
d69dece5 | 331 | if (retval) { |
f9bb4882 | 332 | sysfs_remove_mount_point(kernel_kobj, "security"); |
d69dece5 CS |
333 | return retval; |
334 | } | |
335 | #ifdef CONFIG_SECURITY | |
336 | lsm_dentry = securityfs_create_file("lsm", 0444, NULL, NULL, | |
337 | &lsm_ops); | |
338 | #endif | |
339 | return 0; | |
b67dbf9d | 340 | } |
b67dbf9d | 341 | core_initcall(securityfs_init); |