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v6.2
  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 *  inode.c - securityfs
  4 *
  5 *  Copyright (C) 2005 Greg Kroah-Hartman <gregkh@suse.de>
  6 *
  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 */
 13#include <linux/sysfs.h>
 14#include <linux/kobject.h>
 15#include <linux/fs.h>
 16#include <linux/fs_context.h>
 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>
 22#include <linux/lsm_hooks.h>
 23#include <linux/magic.h>
 24
 25static struct vfsmount *mount;
 26static int mount_count;
 27
 28static void securityfs_free_inode(struct inode *inode)
 29{
 30	if (S_ISLNK(inode->i_mode))
 31		kfree(inode->i_link);
 32	free_inode_nonrcu(inode);
 33}
 34
 35static const struct super_operations securityfs_super_operations = {
 36	.statfs		= simple_statfs,
 37	.free_inode	= securityfs_free_inode,
 38};
 39
 40static int securityfs_fill_super(struct super_block *sb, struct fs_context *fc)
 41{
 42	static const struct tree_descr files[] = {{""}};
 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;
 50
 51	return 0;
 52}
 53
 54static int securityfs_get_tree(struct fs_context *fc)
 55{
 56	return get_tree_single(fc, securityfs_fill_super);
 57}
 58
 59static const struct fs_context_operations securityfs_context_ops = {
 60	.get_tree	= securityfs_get_tree,
 61};
 62
 63static int securityfs_init_fs_context(struct fs_context *fc)
 64{
 65	fc->ops = &securityfs_context_ops;
 66	return 0;
 67}
 68
 69static struct file_system_type fs_type = {
 70	.owner =	THIS_MODULE,
 71	.name =		"securityfs",
 72	.init_fs_context = securityfs_init_fs_context,
 73	.kill_sb =	kill_litter_super,
 74};
 75
 76/**
 77 * securityfs_create_dentry - create a dentry in the securityfs filesystem
 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
 82 *          directory dentry if set.  If this parameter is %NULL, then the
 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
 85 *        on.  The inode.i_private pointer will point to this value on
 86 *        the open() call.
 87 * @fops: a pointer to a struct file_operations that should be used for
 88 *        this file.
 89 * @iops: a point to a struct of inode_operations that should be used for
 90 *        this file/dir
 91 *
 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).
 97 *
 98 * This function returns a pointer to a dentry if it succeeds.  This
 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).
103 *
104 * If securityfs is not enabled in the kernel, the value %-ENODEV is
105 * returned.
106 */
107static 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)
111{
112	struct dentry *dentry;
113	struct inode *dir, *inode;
114	int error;
115
116	if (!(mode & S_IFMT))
117		mode = (mode & S_IALLUGO) | S_IFREG;
118
119	pr_debug("securityfs: creating file '%s'\n",name);
120
121	error = simple_pin_fs(&fs_type, &mount, &mount_count);
122	if (error)
123		return ERR_PTR(error);
124
125	if (!parent)
126		parent = mount->mnt_root;
127
128	dir = d_inode(parent);
129
130	inode_lock(dir);
131	dentry = lookup_one_len(name, parent, strlen(name));
132	if (IS_ERR(dentry))
133		goto out;
134
135	if (d_really_is_positive(dentry)) {
136		error = -EEXIST;
137		goto out1;
138	}
139
140	inode = new_inode(dir->i_sb);
141	if (!inode) {
142		error = -ENOMEM;
143		goto out1;
144	}
145
146	inode->i_ino = get_next_ino();
147	inode->i_mode = mode;
148	inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
149	inode->i_private = data;
150	if (S_ISDIR(mode)) {
151		inode->i_op = &simple_dir_inode_operations;
152		inode->i_fop = &simple_dir_operations;
153		inc_nlink(inode);
154		inc_nlink(dir);
155	} else if (S_ISLNK(mode)) {
156		inode->i_op = iops ? iops : &simple_symlink_inode_operations;
157		inode->i_link = data;
158	} else {
159		inode->i_fop = fops;
160	}
161	d_instantiate(dentry, inode);
162	dget(dentry);
163	inode_unlock(dir);
164	return dentry;
165
166out1:
167	dput(dentry);
168	dentry = ERR_PTR(error);
169out:
170	inode_unlock(dir);
171	simple_release_fs(&mount, &mount_count);
172	return dentry;
173}
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 */
200struct 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}
206EXPORT_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
214 *          directory dentry if set.  If this parameter is %NULL, then the
215 *          directory will be created in the root of the securityfs filesystem.
216 *
217 * This function creates a directory in securityfs with the given @name.
218 *
219 * This function returns a pointer to a dentry if it succeeds.  This
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,
222 * you are responsible here).  If an error occurs, the function will return
223 * the error value (via ERR_PTR).
224 *
225 * If securityfs is not enabled in the kernel, the value %-ENODEV is
226 * returned.
227 */
228struct dentry *securityfs_create_dir(const char *name, struct dentry *parent)
229{
230	return securityfs_create_file(name, S_IFDIR | 0755, parent, NULL, NULL);
231}
232EXPORT_SYMBOL_GPL(securityfs_create_dir);
233
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 */
260struct 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}
280EXPORT_SYMBOL_GPL(securityfs_create_symlink);
281
282/**
283 * securityfs_remove - removes a file or directory from the securityfs filesystem
284 *
285 * @dentry: a pointer to a the dentry of the file or directory to be removed.
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
292 * removed. No automatic cleanup of files will happen when a module is
293 * removed; you are responsible here.
294 */
295void securityfs_remove(struct dentry *dentry)
296{
297	struct inode *dir;
298
299	if (!dentry || IS_ERR(dentry))
300		return;
301
302	dir = d_inode(dentry->d_parent);
303	inode_lock(dir);
304	if (simple_positive(dentry)) {
305		if (d_is_dir(dentry))
306			simple_rmdir(dir, dentry);
307		else
308			simple_unlink(dir, dentry);
309		dput(dentry);
310	}
311	inode_unlock(dir);
312	simple_release_fs(&mount, &mount_count);
313}
314EXPORT_SYMBOL_GPL(securityfs_remove);
315
316#ifdef CONFIG_SECURITY
317static struct dentry *lsm_dentry;
318static 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
325static const struct file_operations lsm_ops = {
326	.read = lsm_read,
327	.llseek = generic_file_llseek,
328};
329#endif
330
331static int __init securityfs_init(void)
332{
333	int retval;
334
335	retval = sysfs_create_mount_point(kernel_kobj, "security");
336	if (retval)
337		return retval;
338
339	retval = register_filesystem(&fs_type);
340	if (retval) {
341		sysfs_remove_mount_point(kernel_kobj, "security");
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;
349}
350core_initcall(securityfs_init);
v6.8
  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 *  inode.c - securityfs
  4 *
  5 *  Copyright (C) 2005 Greg Kroah-Hartman <gregkh@suse.de>
  6 *
  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 */
 13#include <linux/sysfs.h>
 14#include <linux/kobject.h>
 15#include <linux/fs.h>
 16#include <linux/fs_context.h>
 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>
 22#include <linux/lsm_hooks.h>
 23#include <linux/magic.h>
 24
 25static struct vfsmount *mount;
 26static int mount_count;
 27
 28static void securityfs_free_inode(struct inode *inode)
 29{
 30	if (S_ISLNK(inode->i_mode))
 31		kfree(inode->i_link);
 32	free_inode_nonrcu(inode);
 33}
 34
 35static const struct super_operations securityfs_super_operations = {
 36	.statfs		= simple_statfs,
 37	.free_inode	= securityfs_free_inode,
 38};
 39
 40static int securityfs_fill_super(struct super_block *sb, struct fs_context *fc)
 41{
 42	static const struct tree_descr files[] = {{""}};
 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;
 50
 51	return 0;
 52}
 53
 54static int securityfs_get_tree(struct fs_context *fc)
 55{
 56	return get_tree_single(fc, securityfs_fill_super);
 57}
 58
 59static const struct fs_context_operations securityfs_context_ops = {
 60	.get_tree	= securityfs_get_tree,
 61};
 62
 63static int securityfs_init_fs_context(struct fs_context *fc)
 64{
 65	fc->ops = &securityfs_context_ops;
 66	return 0;
 67}
 68
 69static struct file_system_type fs_type = {
 70	.owner =	THIS_MODULE,
 71	.name =		"securityfs",
 72	.init_fs_context = securityfs_init_fs_context,
 73	.kill_sb =	kill_litter_super,
 74};
 75
 76/**
 77 * securityfs_create_dentry - create a dentry in the securityfs filesystem
 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
 82 *          directory dentry if set.  If this parameter is %NULL, then the
 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
 85 *        on.  The inode.i_private pointer will point to this value on
 86 *        the open() call.
 87 * @fops: a pointer to a struct file_operations that should be used for
 88 *        this file.
 89 * @iops: a point to a struct of inode_operations that should be used for
 90 *        this file/dir
 91 *
 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).
 97 *
 98 * This function returns a pointer to a dentry if it succeeds.  This
 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).
103 *
104 * If securityfs is not enabled in the kernel, the value %-ENODEV is
105 * returned.
106 */
107static 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)
111{
112	struct dentry *dentry;
113	struct inode *dir, *inode;
114	int error;
115
116	if (!(mode & S_IFMT))
117		mode = (mode & S_IALLUGO) | S_IFREG;
118
119	pr_debug("securityfs: creating file '%s'\n",name);
120
121	error = simple_pin_fs(&fs_type, &mount, &mount_count);
122	if (error)
123		return ERR_PTR(error);
124
125	if (!parent)
126		parent = mount->mnt_root;
127
128	dir = d_inode(parent);
129
130	inode_lock(dir);
131	dentry = lookup_one_len(name, parent, strlen(name));
132	if (IS_ERR(dentry))
133		goto out;
134
135	if (d_really_is_positive(dentry)) {
136		error = -EEXIST;
137		goto out1;
138	}
139
140	inode = new_inode(dir->i_sb);
141	if (!inode) {
142		error = -ENOMEM;
143		goto out1;
144	}
145
146	inode->i_ino = get_next_ino();
147	inode->i_mode = mode;
148	simple_inode_init_ts(inode);
149	inode->i_private = data;
150	if (S_ISDIR(mode)) {
151		inode->i_op = &simple_dir_inode_operations;
152		inode->i_fop = &simple_dir_operations;
153		inc_nlink(inode);
154		inc_nlink(dir);
155	} else if (S_ISLNK(mode)) {
156		inode->i_op = iops ? iops : &simple_symlink_inode_operations;
157		inode->i_link = data;
158	} else {
159		inode->i_fop = fops;
160	}
161	d_instantiate(dentry, inode);
162	dget(dentry);
163	inode_unlock(dir);
164	return dentry;
165
166out1:
167	dput(dentry);
168	dentry = ERR_PTR(error);
169out:
170	inode_unlock(dir);
171	simple_release_fs(&mount, &mount_count);
172	return dentry;
173}
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 */
200struct 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}
206EXPORT_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
214 *          directory dentry if set.  If this parameter is %NULL, then the
215 *          directory will be created in the root of the securityfs filesystem.
216 *
217 * This function creates a directory in securityfs with the given @name.
218 *
219 * This function returns a pointer to a dentry if it succeeds.  This
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,
222 * you are responsible here).  If an error occurs, the function will return
223 * the error value (via ERR_PTR).
224 *
225 * If securityfs is not enabled in the kernel, the value %-ENODEV is
226 * returned.
227 */
228struct dentry *securityfs_create_dir(const char *name, struct dentry *parent)
229{
230	return securityfs_create_file(name, S_IFDIR | 0755, parent, NULL, NULL);
231}
232EXPORT_SYMBOL_GPL(securityfs_create_dir);
233
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 */
260struct 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}
280EXPORT_SYMBOL_GPL(securityfs_create_symlink);
281
282/**
283 * securityfs_remove - removes a file or directory from the securityfs filesystem
284 *
285 * @dentry: a pointer to a the dentry of the file or directory to be removed.
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
292 * removed. No automatic cleanup of files will happen when a module is
293 * removed; you are responsible here.
294 */
295void securityfs_remove(struct dentry *dentry)
296{
297	struct inode *dir;
298
299	if (!dentry || IS_ERR(dentry))
300		return;
301
302	dir = d_inode(dentry->d_parent);
303	inode_lock(dir);
304	if (simple_positive(dentry)) {
305		if (d_is_dir(dentry))
306			simple_rmdir(dir, dentry);
307		else
308			simple_unlink(dir, dentry);
309		dput(dentry);
310	}
311	inode_unlock(dir);
312	simple_release_fs(&mount, &mount_count);
313}
314EXPORT_SYMBOL_GPL(securityfs_remove);
315
316#ifdef CONFIG_SECURITY
317static struct dentry *lsm_dentry;
318static 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
325static const struct file_operations lsm_ops = {
326	.read = lsm_read,
327	.llseek = generic_file_llseek,
328};
329#endif
330
331static int __init securityfs_init(void)
332{
333	int retval;
334
335	retval = sysfs_create_mount_point(kernel_kobj, "security");
336	if (retval)
337		return retval;
338
339	retval = register_filesystem(&fs_type);
340	if (retval) {
341		sysfs_remove_mount_point(kernel_kobj, "security");
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;
349}
350core_initcall(securityfs_init);