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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 | ||
f614ee1e | 30 | static void securityfs_free_inode(struct inode *inode) |
6623ec7c | 31 | { |
6623ec7c JJ |
32 | if (S_ISLNK(inode->i_mode)) |
33 | kfree(inode->i_link); | |
46c87441 AV |
34 | free_inode_nonrcu(inode); |
35 | } | |
36 | ||
6623ec7c JJ |
37 | static const struct super_operations securityfs_super_operations = { |
38 | .statfs = simple_statfs, | |
f614ee1e | 39 | .free_inode = securityfs_free_inode, |
6623ec7c JJ |
40 | }; |
41 | ||
b67dbf9d GKH |
42 | static int fill_super(struct super_block *sb, void *data, int silent) |
43 | { | |
cda37124 | 44 | static const struct tree_descr files[] = {{""}}; |
6623ec7c JJ |
45 | int error; |
46 | ||
47 | error = simple_fill_super(sb, SECURITYFS_MAGIC, files); | |
48 | if (error) | |
49 | return error; | |
50 | ||
51 | sb->s_op = &securityfs_super_operations; | |
b67dbf9d | 52 | |
6623ec7c | 53 | return 0; |
b67dbf9d GKH |
54 | } |
55 | ||
fc14f2fe | 56 | static struct dentry *get_sb(struct file_system_type *fs_type, |
454e2398 | 57 | int flags, const char *dev_name, |
fc14f2fe | 58 | void *data) |
b67dbf9d | 59 | { |
fc14f2fe | 60 | return mount_single(fs_type, flags, data, fill_super); |
b67dbf9d GKH |
61 | } |
62 | ||
63 | static struct file_system_type fs_type = { | |
64 | .owner = THIS_MODULE, | |
65 | .name = "securityfs", | |
fc14f2fe | 66 | .mount = get_sb, |
b67dbf9d GKH |
67 | .kill_sb = kill_litter_super, |
68 | }; | |
69 | ||
b67dbf9d | 70 | /** |
6623ec7c | 71 | * securityfs_create_dentry - create a dentry in the securityfs filesystem |
b67dbf9d GKH |
72 | * |
73 | * @name: a pointer to a string containing the name of the file to create. | |
74 | * @mode: the permission that the file should have | |
75 | * @parent: a pointer to the parent dentry for this file. This should be a | |
3f23d815 | 76 | * directory dentry if set. If this parameter is %NULL, then the |
b67dbf9d GKH |
77 | * file will be created in the root of the securityfs filesystem. |
78 | * @data: a pointer to something that the caller will want to get to later | |
8e18e294 | 79 | * on. The inode.i_private pointer will point to this value on |
b67dbf9d GKH |
80 | * the open() call. |
81 | * @fops: a pointer to a struct file_operations that should be used for | |
82 | * this file. | |
6623ec7c JJ |
83 | * @iops: a point to a struct of inode_operations that should be used for |
84 | * this file/dir | |
b67dbf9d | 85 | * |
6623ec7c JJ |
86 | * This is the basic "create a file/dir/symlink" function for |
87 | * securityfs. It allows for a wide range of flexibility in creating | |
88 | * a file, or a directory (if you want to create a directory, the | |
89 | * securityfs_create_dir() function is recommended to be used | |
90 | * instead). | |
b67dbf9d | 91 | * |
3f23d815 | 92 | * This function returns a pointer to a dentry if it succeeds. This |
6623ec7c JJ |
93 | * pointer must be passed to the securityfs_remove() function when the |
94 | * file is to be removed (no automatic cleanup happens if your module | |
95 | * is unloaded, you are responsible here). If an error occurs, the | |
96 | * function will return the error value (via ERR_PTR). | |
b67dbf9d | 97 | * |
3f23d815 | 98 | * If securityfs is not enabled in the kernel, the value %-ENODEV is |
faa3aad7 | 99 | * returned. |
b67dbf9d | 100 | */ |
6623ec7c JJ |
101 | static struct dentry *securityfs_create_dentry(const char *name, umode_t mode, |
102 | struct dentry *parent, void *data, | |
103 | const struct file_operations *fops, | |
104 | const struct inode_operations *iops) | |
b67dbf9d | 105 | { |
3e25eb9c | 106 | struct dentry *dentry; |
3e25eb9c | 107 | struct inode *dir, *inode; |
b67dbf9d GKH |
108 | int error; |
109 | ||
6623ec7c | 110 | if (!(mode & S_IFMT)) |
3e25eb9c | 111 | mode = (mode & S_IALLUGO) | S_IFREG; |
3e25eb9c | 112 | |
b67dbf9d GKH |
113 | pr_debug("securityfs: creating file '%s'\n",name); |
114 | ||
1f5ce9e9 | 115 | error = simple_pin_fs(&fs_type, &mount, &mount_count); |
3e25eb9c AV |
116 | if (error) |
117 | return ERR_PTR(error); | |
118 | ||
119 | if (!parent) | |
120 | parent = mount->mnt_root; | |
121 | ||
ce0b16dd | 122 | dir = d_inode(parent); |
3e25eb9c | 123 | |
5955102c | 124 | inode_lock(dir); |
3e25eb9c AV |
125 | dentry = lookup_one_len(name, parent, strlen(name)); |
126 | if (IS_ERR(dentry)) | |
127 | goto out; | |
128 | ||
ce0b16dd | 129 | if (d_really_is_positive(dentry)) { |
3e25eb9c AV |
130 | error = -EEXIST; |
131 | goto out1; | |
b67dbf9d GKH |
132 | } |
133 | ||
3e25eb9c AV |
134 | inode = new_inode(dir->i_sb); |
135 | if (!inode) { | |
136 | error = -ENOMEM; | |
137 | goto out1; | |
b67dbf9d GKH |
138 | } |
139 | ||
3e25eb9c AV |
140 | inode->i_ino = get_next_ino(); |
141 | inode->i_mode = mode; | |
078cd827 | 142 | inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode); |
3e25eb9c | 143 | inode->i_private = data; |
6623ec7c | 144 | if (S_ISDIR(mode)) { |
3e25eb9c AV |
145 | inode->i_op = &simple_dir_inode_operations; |
146 | inode->i_fop = &simple_dir_operations; | |
147 | inc_nlink(inode); | |
148 | inc_nlink(dir); | |
6623ec7c JJ |
149 | } else if (S_ISLNK(mode)) { |
150 | inode->i_op = iops ? iops : &simple_symlink_inode_operations; | |
151 | inode->i_link = data; | |
3e25eb9c AV |
152 | } else { |
153 | inode->i_fop = fops; | |
b67dbf9d | 154 | } |
3e25eb9c AV |
155 | d_instantiate(dentry, inode); |
156 | dget(dentry); | |
5955102c | 157 | inode_unlock(dir); |
3e25eb9c AV |
158 | return dentry; |
159 | ||
160 | out1: | |
161 | dput(dentry); | |
162 | dentry = ERR_PTR(error); | |
163 | out: | |
5955102c | 164 | inode_unlock(dir); |
3e25eb9c | 165 | simple_release_fs(&mount, &mount_count); |
b67dbf9d GKH |
166 | return dentry; |
167 | } | |
6623ec7c JJ |
168 | |
169 | /** | |
170 | * securityfs_create_file - create a file in the securityfs filesystem | |
171 | * | |
172 | * @name: a pointer to a string containing the name of the file to create. | |
173 | * @mode: the permission that the file should have | |
174 | * @parent: a pointer to the parent dentry for this file. This should be a | |
175 | * directory dentry if set. If this parameter is %NULL, then the | |
176 | * file will be created in the root of the securityfs filesystem. | |
177 | * @data: a pointer to something that the caller will want to get to later | |
178 | * on. The inode.i_private pointer will point to this value on | |
179 | * the open() call. | |
180 | * @fops: a pointer to a struct file_operations that should be used for | |
181 | * this file. | |
182 | * | |
183 | * This function creates a file in securityfs with the given @name. | |
184 | * | |
185 | * This function returns a pointer to a dentry if it succeeds. This | |
186 | * pointer must be passed to the securityfs_remove() function when the file is | |
187 | * to be removed (no automatic cleanup happens if your module is unloaded, | |
188 | * you are responsible here). If an error occurs, the function will return | |
189 | * the error value (via ERR_PTR). | |
190 | * | |
191 | * If securityfs is not enabled in the kernel, the value %-ENODEV is | |
192 | * returned. | |
193 | */ | |
194 | struct dentry *securityfs_create_file(const char *name, umode_t mode, | |
195 | struct dentry *parent, void *data, | |
196 | const struct file_operations *fops) | |
197 | { | |
198 | return securityfs_create_dentry(name, mode, parent, data, fops, NULL); | |
199 | } | |
b67dbf9d GKH |
200 | EXPORT_SYMBOL_GPL(securityfs_create_file); |
201 | ||
202 | /** | |
203 | * securityfs_create_dir - create a directory in the securityfs filesystem | |
204 | * | |
205 | * @name: a pointer to a string containing the name of the directory to | |
206 | * create. | |
207 | * @parent: a pointer to the parent dentry for this file. This should be a | |
3f23d815 | 208 | * directory dentry if set. If this parameter is %NULL, then the |
b67dbf9d GKH |
209 | * directory will be created in the root of the securityfs filesystem. |
210 | * | |
3f23d815 | 211 | * This function creates a directory in securityfs with the given @name. |
b67dbf9d | 212 | * |
3f23d815 | 213 | * This function returns a pointer to a dentry if it succeeds. This |
b67dbf9d GKH |
214 | * pointer must be passed to the securityfs_remove() function when the file is |
215 | * to be removed (no automatic cleanup happens if your module is unloaded, | |
1b460651 LG |
216 | * you are responsible here). If an error occurs, the function will return |
217 | * the error value (via ERR_PTR). | |
b67dbf9d | 218 | * |
3f23d815 | 219 | * If securityfs is not enabled in the kernel, the value %-ENODEV is |
1b460651 | 220 | * returned. |
b67dbf9d GKH |
221 | */ |
222 | struct dentry *securityfs_create_dir(const char *name, struct dentry *parent) | |
223 | { | |
6623ec7c | 224 | return securityfs_create_file(name, S_IFDIR | 0755, parent, NULL, NULL); |
b67dbf9d GKH |
225 | } |
226 | EXPORT_SYMBOL_GPL(securityfs_create_dir); | |
227 | ||
6623ec7c JJ |
228 | /** |
229 | * securityfs_create_symlink - create a symlink in the securityfs filesystem | |
230 | * | |
231 | * @name: a pointer to a string containing the name of the symlink to | |
232 | * create. | |
233 | * @parent: a pointer to the parent dentry for the symlink. This should be a | |
234 | * directory dentry if set. If this parameter is %NULL, then the | |
235 | * directory will be created in the root of the securityfs filesystem. | |
236 | * @target: a pointer to a string containing the name of the symlink's target. | |
237 | * If this parameter is %NULL, then the @iops parameter needs to be | |
238 | * setup to handle .readlink and .get_link inode_operations. | |
239 | * @iops: a pointer to the struct inode_operations to use for the symlink. If | |
240 | * this parameter is %NULL, then the default simple_symlink_inode | |
241 | * operations will be used. | |
242 | * | |
243 | * This function creates a symlink in securityfs with the given @name. | |
244 | * | |
245 | * This function returns a pointer to a dentry if it succeeds. This | |
246 | * pointer must be passed to the securityfs_remove() function when the file is | |
247 | * to be removed (no automatic cleanup happens if your module is unloaded, | |
248 | * you are responsible here). If an error occurs, the function will return | |
249 | * the error value (via ERR_PTR). | |
250 | * | |
251 | * If securityfs is not enabled in the kernel, the value %-ENODEV is | |
252 | * returned. | |
253 | */ | |
254 | struct dentry *securityfs_create_symlink(const char *name, | |
255 | struct dentry *parent, | |
256 | const char *target, | |
257 | const struct inode_operations *iops) | |
258 | { | |
259 | struct dentry *dent; | |
260 | char *link = NULL; | |
261 | ||
262 | if (target) { | |
263 | link = kstrdup(target, GFP_KERNEL); | |
264 | if (!link) | |
265 | return ERR_PTR(-ENOMEM); | |
266 | } | |
267 | dent = securityfs_create_dentry(name, S_IFLNK | 0444, parent, | |
268 | link, NULL, iops); | |
269 | if (IS_ERR(dent)) | |
270 | kfree(link); | |
271 | ||
272 | return dent; | |
273 | } | |
274 | EXPORT_SYMBOL_GPL(securityfs_create_symlink); | |
275 | ||
b67dbf9d GKH |
276 | /** |
277 | * securityfs_remove - removes a file or directory from the securityfs filesystem | |
278 | * | |
3f23d815 | 279 | * @dentry: a pointer to a the dentry of the file or directory to be removed. |
b67dbf9d GKH |
280 | * |
281 | * This function removes a file or directory in securityfs that was previously | |
282 | * created with a call to another securityfs function (like | |
283 | * securityfs_create_file() or variants thereof.) | |
284 | * | |
285 | * This function is required to be called in order for the file to be | |
3f23d815 RD |
286 | * removed. No automatic cleanup of files will happen when a module is |
287 | * removed; you are responsible here. | |
b67dbf9d GKH |
288 | */ |
289 | void securityfs_remove(struct dentry *dentry) | |
290 | { | |
4093d306 | 291 | struct inode *dir; |
b67dbf9d | 292 | |
d93e4c94 | 293 | if (!dentry || IS_ERR(dentry)) |
b67dbf9d GKH |
294 | return; |
295 | ||
4093d306 AV |
296 | dir = d_inode(dentry->d_parent); |
297 | inode_lock(dir); | |
dc3f4198 AV |
298 | if (simple_positive(dentry)) { |
299 | if (d_is_dir(dentry)) | |
4093d306 | 300 | simple_rmdir(dir, dentry); |
dc3f4198 | 301 | else |
4093d306 | 302 | simple_unlink(dir, dentry); |
dc3f4198 | 303 | dput(dentry); |
b67dbf9d | 304 | } |
4093d306 | 305 | inode_unlock(dir); |
b67dbf9d GKH |
306 | simple_release_fs(&mount, &mount_count); |
307 | } | |
308 | EXPORT_SYMBOL_GPL(securityfs_remove); | |
309 | ||
d69dece5 CS |
310 | #ifdef CONFIG_SECURITY |
311 | static struct dentry *lsm_dentry; | |
312 | static ssize_t lsm_read(struct file *filp, char __user *buf, size_t count, | |
313 | loff_t *ppos) | |
314 | { | |
315 | return simple_read_from_buffer(buf, count, ppos, lsm_names, | |
316 | strlen(lsm_names)); | |
317 | } | |
318 | ||
319 | static const struct file_operations lsm_ops = { | |
320 | .read = lsm_read, | |
321 | .llseek = generic_file_llseek, | |
322 | }; | |
323 | #endif | |
324 | ||
b67dbf9d GKH |
325 | static int __init securityfs_init(void) |
326 | { | |
327 | int retval; | |
328 | ||
f9bb4882 EB |
329 | retval = sysfs_create_mount_point(kernel_kobj, "security"); |
330 | if (retval) | |
331 | return retval; | |
b67dbf9d GKH |
332 | |
333 | retval = register_filesystem(&fs_type); | |
d69dece5 | 334 | if (retval) { |
f9bb4882 | 335 | sysfs_remove_mount_point(kernel_kobj, "security"); |
d69dece5 CS |
336 | return retval; |
337 | } | |
338 | #ifdef CONFIG_SECURITY | |
339 | lsm_dentry = securityfs_create_file("lsm", 0444, NULL, NULL, | |
340 | &lsm_ops); | |
341 | #endif | |
342 | return 0; | |
b67dbf9d | 343 | } |
b67dbf9d | 344 | core_initcall(securityfs_init); |