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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 | 15 | #include <linux/fs.h> |
5c86d7e0 | 16 | #include <linux/fs_context.h> |
b67dbf9d GK |
17 | #include <linux/mount.h> |
18 | #include <linux/pagemap.h> | |
19 | #include <linux/init.h> | |
20 | #include <linux/namei.h> | |
21 | #include <linux/security.h> | |
d69dece5 | 22 | #include <linux/lsm_hooks.h> |
92562927 | 23 | #include <linux/magic.h> |
b67dbf9d GK |
24 | |
25 | static struct vfsmount *mount; | |
26 | static int mount_count; | |
27 | ||
f614ee1e | 28 | static void securityfs_free_inode(struct inode *inode) |
6623ec7c | 29 | { |
6623ec7c JJ |
30 | if (S_ISLNK(inode->i_mode)) |
31 | kfree(inode->i_link); | |
46c87441 AV |
32 | free_inode_nonrcu(inode); |
33 | } | |
34 | ||
6623ec7c JJ |
35 | static const struct super_operations securityfs_super_operations = { |
36 | .statfs = simple_statfs, | |
f614ee1e | 37 | .free_inode = securityfs_free_inode, |
6623ec7c JJ |
38 | }; |
39 | ||
5c86d7e0 | 40 | static int securityfs_fill_super(struct super_block *sb, struct fs_context *fc) |
b67dbf9d | 41 | { |
cda37124 | 42 | static const struct tree_descr files[] = {{""}}; |
6623ec7c JJ |
43 | int error; |
44 | ||
45 | error = simple_fill_super(sb, SECURITYFS_MAGIC, files); | |
46 | if (error) | |
47 | return error; | |
48 | ||
49 | sb->s_op = &securityfs_super_operations; | |
b67dbf9d | 50 | |
6623ec7c | 51 | return 0; |
b67dbf9d GK |
52 | } |
53 | ||
5c86d7e0 | 54 | static int securityfs_get_tree(struct fs_context *fc) |
b67dbf9d | 55 | { |
5c86d7e0 DH |
56 | return get_tree_single(fc, securityfs_fill_super); |
57 | } | |
58 | ||
59 | static const struct fs_context_operations securityfs_context_ops = { | |
60 | .get_tree = securityfs_get_tree, | |
61 | }; | |
62 | ||
63 | static int securityfs_init_fs_context(struct fs_context *fc) | |
64 | { | |
65 | fc->ops = &securityfs_context_ops; | |
66 | return 0; | |
b67dbf9d GK |
67 | } |
68 | ||
69 | static struct file_system_type fs_type = { | |
70 | .owner = THIS_MODULE, | |
71 | .name = "securityfs", | |
5c86d7e0 | 72 | .init_fs_context = securityfs_init_fs_context, |
b67dbf9d GK |
73 | .kill_sb = kill_litter_super, |
74 | }; | |
75 | ||
b67dbf9d | 76 | /** |
6623ec7c | 77 | * securityfs_create_dentry - create a dentry in the securityfs filesystem |
b67dbf9d GK |
78 | * |
79 | * @name: a pointer to a string containing the name of the file to create. | |
80 | * @mode: the permission that the file should have | |
81 | * @parent: a pointer to the parent dentry for this file. This should be a | |
3f23d815 | 82 | * directory dentry if set. If this parameter is %NULL, then the |
b67dbf9d GK |
83 | * file will be created in the root of the securityfs filesystem. |
84 | * @data: a pointer to something that the caller will want to get to later | |
8e18e294 | 85 | * on. The inode.i_private pointer will point to this value on |
b67dbf9d GK |
86 | * the open() call. |
87 | * @fops: a pointer to a struct file_operations that should be used for | |
88 | * this file. | |
6623ec7c JJ |
89 | * @iops: a point to a struct of inode_operations that should be used for |
90 | * this file/dir | |
b67dbf9d | 91 | * |
6623ec7c JJ |
92 | * This is the basic "create a file/dir/symlink" function for |
93 | * securityfs. It allows for a wide range of flexibility in creating | |
94 | * a file, or a directory (if you want to create a directory, the | |
95 | * securityfs_create_dir() function is recommended to be used | |
96 | * instead). | |
b67dbf9d | 97 | * |
3f23d815 | 98 | * This function returns a pointer to a dentry if it succeeds. This |
6623ec7c JJ |
99 | * pointer must be passed to the securityfs_remove() function when the |
100 | * file is to be removed (no automatic cleanup happens if your module | |
101 | * is unloaded, you are responsible here). If an error occurs, the | |
102 | * function will return the error value (via ERR_PTR). | |
b67dbf9d | 103 | * |
3f23d815 | 104 | * If securityfs is not enabled in the kernel, the value %-ENODEV is |
faa3aad7 | 105 | * returned. |
b67dbf9d | 106 | */ |
6623ec7c JJ |
107 | static struct dentry *securityfs_create_dentry(const char *name, umode_t mode, |
108 | struct dentry *parent, void *data, | |
109 | const struct file_operations *fops, | |
110 | const struct inode_operations *iops) | |
b67dbf9d | 111 | { |
3e25eb9c | 112 | struct dentry *dentry; |
3e25eb9c | 113 | struct inode *dir, *inode; |
b67dbf9d GK |
114 | int error; |
115 | ||
6623ec7c | 116 | if (!(mode & S_IFMT)) |
3e25eb9c | 117 | mode = (mode & S_IALLUGO) | S_IFREG; |
3e25eb9c | 118 | |
b67dbf9d GK |
119 | pr_debug("securityfs: creating file '%s'\n",name); |
120 | ||
1f5ce9e9 | 121 | error = simple_pin_fs(&fs_type, &mount, &mount_count); |
3e25eb9c AV |
122 | if (error) |
123 | return ERR_PTR(error); | |
124 | ||
125 | if (!parent) | |
126 | parent = mount->mnt_root; | |
127 | ||
ce0b16dd | 128 | dir = d_inode(parent); |
3e25eb9c | 129 | |
5955102c | 130 | inode_lock(dir); |
3e25eb9c AV |
131 | dentry = lookup_one_len(name, parent, strlen(name)); |
132 | if (IS_ERR(dentry)) | |
133 | goto out; | |
134 | ||
ce0b16dd | 135 | if (d_really_is_positive(dentry)) { |
3e25eb9c AV |
136 | error = -EEXIST; |
137 | goto out1; | |
b67dbf9d GK |
138 | } |
139 | ||
3e25eb9c AV |
140 | inode = new_inode(dir->i_sb); |
141 | if (!inode) { | |
142 | error = -ENOMEM; | |
143 | goto out1; | |
b67dbf9d GK |
144 | } |
145 | ||
3e25eb9c AV |
146 | inode->i_ino = get_next_ino(); |
147 | inode->i_mode = mode; | |
078cd827 | 148 | inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); |
3e25eb9c | 149 | inode->i_private = data; |
6623ec7c | 150 | if (S_ISDIR(mode)) { |
3e25eb9c AV |
151 | inode->i_op = &simple_dir_inode_operations; |
152 | inode->i_fop = &simple_dir_operations; | |
153 | inc_nlink(inode); | |
154 | inc_nlink(dir); | |
6623ec7c JJ |
155 | } else if (S_ISLNK(mode)) { |
156 | inode->i_op = iops ? iops : &simple_symlink_inode_operations; | |
157 | inode->i_link = data; | |
3e25eb9c AV |
158 | } else { |
159 | inode->i_fop = fops; | |
b67dbf9d | 160 | } |
3e25eb9c AV |
161 | d_instantiate(dentry, inode); |
162 | dget(dentry); | |
5955102c | 163 | inode_unlock(dir); |
3e25eb9c AV |
164 | return dentry; |
165 | ||
166 | out1: | |
167 | dput(dentry); | |
168 | dentry = ERR_PTR(error); | |
169 | out: | |
5955102c | 170 | inode_unlock(dir); |
3e25eb9c | 171 | simple_release_fs(&mount, &mount_count); |
b67dbf9d GK |
172 | return dentry; |
173 | } | |
6623ec7c JJ |
174 | |
175 | /** | |
176 | * securityfs_create_file - create a file in the securityfs filesystem | |
177 | * | |
178 | * @name: a pointer to a string containing the name of the file to create. | |
179 | * @mode: the permission that the file should have | |
180 | * @parent: a pointer to the parent dentry for this file. This should be a | |
181 | * directory dentry if set. If this parameter is %NULL, then the | |
182 | * file will be created in the root of the securityfs filesystem. | |
183 | * @data: a pointer to something that the caller will want to get to later | |
184 | * on. The inode.i_private pointer will point to this value on | |
185 | * the open() call. | |
186 | * @fops: a pointer to a struct file_operations that should be used for | |
187 | * this file. | |
188 | * | |
189 | * This function creates a file in securityfs with the given @name. | |
190 | * | |
191 | * This function returns a pointer to a dentry if it succeeds. This | |
192 | * pointer must be passed to the securityfs_remove() function when the file is | |
193 | * to be removed (no automatic cleanup happens if your module is unloaded, | |
194 | * you are responsible here). If an error occurs, the function will return | |
195 | * the error value (via ERR_PTR). | |
196 | * | |
197 | * If securityfs is not enabled in the kernel, the value %-ENODEV is | |
198 | * returned. | |
199 | */ | |
200 | struct dentry *securityfs_create_file(const char *name, umode_t mode, | |
201 | struct dentry *parent, void *data, | |
202 | const struct file_operations *fops) | |
203 | { | |
204 | return securityfs_create_dentry(name, mode, parent, data, fops, NULL); | |
205 | } | |
b67dbf9d GK |
206 | EXPORT_SYMBOL_GPL(securityfs_create_file); |
207 | ||
208 | /** | |
209 | * securityfs_create_dir - create a directory in the securityfs filesystem | |
210 | * | |
211 | * @name: a pointer to a string containing the name of the directory to | |
212 | * create. | |
213 | * @parent: a pointer to the parent dentry for this file. This should be a | |
3f23d815 | 214 | * directory dentry if set. If this parameter is %NULL, then the |
b67dbf9d GK |
215 | * directory will be created in the root of the securityfs filesystem. |
216 | * | |
3f23d815 | 217 | * This function creates a directory in securityfs with the given @name. |
b67dbf9d | 218 | * |
3f23d815 | 219 | * This function returns a pointer to a dentry if it succeeds. This |
b67dbf9d GK |
220 | * pointer must be passed to the securityfs_remove() function when the file is |
221 | * to be removed (no automatic cleanup happens if your module is unloaded, | |
1b460651 LG |
222 | * you are responsible here). If an error occurs, the function will return |
223 | * the error value (via ERR_PTR). | |
b67dbf9d | 224 | * |
3f23d815 | 225 | * If securityfs is not enabled in the kernel, the value %-ENODEV is |
1b460651 | 226 | * returned. |
b67dbf9d GK |
227 | */ |
228 | struct dentry *securityfs_create_dir(const char *name, struct dentry *parent) | |
229 | { | |
6623ec7c | 230 | return securityfs_create_file(name, S_IFDIR | 0755, parent, NULL, NULL); |
b67dbf9d GK |
231 | } |
232 | EXPORT_SYMBOL_GPL(securityfs_create_dir); | |
233 | ||
6623ec7c JJ |
234 | /** |
235 | * securityfs_create_symlink - create a symlink in the securityfs filesystem | |
236 | * | |
237 | * @name: a pointer to a string containing the name of the symlink to | |
238 | * create. | |
239 | * @parent: a pointer to the parent dentry for the symlink. This should be a | |
240 | * directory dentry if set. If this parameter is %NULL, then the | |
241 | * directory will be created in the root of the securityfs filesystem. | |
242 | * @target: a pointer to a string containing the name of the symlink's target. | |
243 | * If this parameter is %NULL, then the @iops parameter needs to be | |
244 | * setup to handle .readlink and .get_link inode_operations. | |
245 | * @iops: a pointer to the struct inode_operations to use for the symlink. If | |
246 | * this parameter is %NULL, then the default simple_symlink_inode | |
247 | * operations will be used. | |
248 | * | |
249 | * This function creates a symlink in securityfs with the given @name. | |
250 | * | |
251 | * This function returns a pointer to a dentry if it succeeds. This | |
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, | |
254 | * you are responsible here). If an error occurs, the function will return | |
255 | * the error value (via ERR_PTR). | |
256 | * | |
257 | * If securityfs is not enabled in the kernel, the value %-ENODEV is | |
258 | * returned. | |
259 | */ | |
260 | struct dentry *securityfs_create_symlink(const char *name, | |
261 | struct dentry *parent, | |
262 | const char *target, | |
263 | const struct inode_operations *iops) | |
264 | { | |
265 | struct dentry *dent; | |
266 | char *link = NULL; | |
267 | ||
268 | if (target) { | |
269 | link = kstrdup(target, GFP_KERNEL); | |
270 | if (!link) | |
271 | return ERR_PTR(-ENOMEM); | |
272 | } | |
273 | dent = securityfs_create_dentry(name, S_IFLNK | 0444, parent, | |
274 | link, NULL, iops); | |
275 | if (IS_ERR(dent)) | |
276 | kfree(link); | |
277 | ||
278 | return dent; | |
279 | } | |
280 | EXPORT_SYMBOL_GPL(securityfs_create_symlink); | |
281 | ||
b67dbf9d GK |
282 | /** |
283 | * securityfs_remove - removes a file or directory from the securityfs filesystem | |
284 | * | |
3f23d815 | 285 | * @dentry: a pointer to a the dentry of the file or directory to be removed. |
b67dbf9d GK |
286 | * |
287 | * This function removes a file or directory in securityfs that was previously | |
288 | * created with a call to another securityfs function (like | |
289 | * securityfs_create_file() or variants thereof.) | |
290 | * | |
291 | * This function is required to be called in order for the file to be | |
3f23d815 RD |
292 | * removed. No automatic cleanup of files will happen when a module is |
293 | * removed; you are responsible here. | |
b67dbf9d GK |
294 | */ |
295 | void securityfs_remove(struct dentry *dentry) | |
296 | { | |
4093d306 | 297 | struct inode *dir; |
b67dbf9d | 298 | |
d93e4c94 | 299 | if (!dentry || IS_ERR(dentry)) |
b67dbf9d GK |
300 | return; |
301 | ||
4093d306 AV |
302 | dir = d_inode(dentry->d_parent); |
303 | inode_lock(dir); | |
dc3f4198 AV |
304 | if (simple_positive(dentry)) { |
305 | if (d_is_dir(dentry)) | |
4093d306 | 306 | simple_rmdir(dir, dentry); |
dc3f4198 | 307 | else |
4093d306 | 308 | simple_unlink(dir, dentry); |
dc3f4198 | 309 | dput(dentry); |
b67dbf9d | 310 | } |
4093d306 | 311 | inode_unlock(dir); |
b67dbf9d GK |
312 | simple_release_fs(&mount, &mount_count); |
313 | } | |
314 | EXPORT_SYMBOL_GPL(securityfs_remove); | |
315 | ||
d69dece5 CS |
316 | #ifdef CONFIG_SECURITY |
317 | static struct dentry *lsm_dentry; | |
318 | static ssize_t lsm_read(struct file *filp, char __user *buf, size_t count, | |
319 | loff_t *ppos) | |
320 | { | |
321 | return simple_read_from_buffer(buf, count, ppos, lsm_names, | |
322 | strlen(lsm_names)); | |
323 | } | |
324 | ||
325 | static const struct file_operations lsm_ops = { | |
326 | .read = lsm_read, | |
327 | .llseek = generic_file_llseek, | |
328 | }; | |
329 | #endif | |
330 | ||
b67dbf9d GK |
331 | static int __init securityfs_init(void) |
332 | { | |
333 | int retval; | |
334 | ||
f9bb4882 EB |
335 | retval = sysfs_create_mount_point(kernel_kobj, "security"); |
336 | if (retval) | |
337 | return retval; | |
b67dbf9d GK |
338 | |
339 | retval = register_filesystem(&fs_type); | |
d69dece5 | 340 | if (retval) { |
f9bb4882 | 341 | sysfs_remove_mount_point(kernel_kobj, "security"); |
d69dece5 CS |
342 | return retval; |
343 | } | |
344 | #ifdef CONFIG_SECURITY | |
345 | lsm_dentry = securityfs_create_file("lsm", 0444, NULL, NULL, | |
346 | &lsm_ops); | |
347 | #endif | |
348 | return 0; | |
b67dbf9d | 349 | } |
b67dbf9d | 350 | core_initcall(securityfs_init); |