1 // SPDX-License-Identifier: GPL-2.0-only
5 * Copyright (C) 2005 Greg Kroah-Hartman <gregkh@suse.de>
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.
13 #include <linux/sysfs.h>
14 #include <linux/kobject.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>
25 static struct vfsmount
*mount
;
26 static int mount_count
;
28 static void securityfs_free_inode(struct inode
*inode
)
30 if (S_ISLNK(inode
->i_mode
))
32 free_inode_nonrcu(inode
);
35 static const struct super_operations securityfs_super_operations
= {
36 .statfs
= simple_statfs
,
37 .free_inode
= securityfs_free_inode
,
40 static int securityfs_fill_super(struct super_block
*sb
, struct fs_context
*fc
)
42 static const struct tree_descr files
[] = {{""}};
45 error
= simple_fill_super(sb
, SECURITYFS_MAGIC
, files
);
49 sb
->s_op
= &securityfs_super_operations
;
54 static int securityfs_get_tree(struct fs_context
*fc
)
56 return get_tree_single(fc
, securityfs_fill_super
);
59 static const struct fs_context_operations securityfs_context_ops
= {
60 .get_tree
= securityfs_get_tree
,
63 static int securityfs_init_fs_context(struct fs_context
*fc
)
65 fc
->ops
= &securityfs_context_ops
;
69 static struct file_system_type fs_type
= {
72 .init_fs_context
= securityfs_init_fs_context
,
73 .kill_sb
= kill_litter_super
,
77 * securityfs_create_dentry - create a dentry in the securityfs filesystem
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
87 * @fops: a pointer to a struct file_operations that should be used for
89 * @iops: a point to a struct of inode_operations that should be used for
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
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).
104 * If securityfs is not enabled in the kernel, the value %-ENODEV is
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
)
112 struct dentry
*dentry
;
113 struct inode
*dir
, *inode
;
116 if (!(mode
& S_IFMT
))
117 mode
= (mode
& S_IALLUGO
) | S_IFREG
;
119 pr_debug("securityfs: creating file '%s'\n",name
);
121 error
= simple_pin_fs(&fs_type
, &mount
, &mount_count
);
123 return ERR_PTR(error
);
126 parent
= mount
->mnt_root
;
128 dir
= d_inode(parent
);
131 dentry
= lookup_one_len(name
, parent
, strlen(name
));
135 if (d_really_is_positive(dentry
)) {
140 inode
= new_inode(dir
->i_sb
);
146 inode
->i_ino
= get_next_ino();
147 inode
->i_mode
= mode
;
148 simple_inode_init_ts(inode
);
149 inode
->i_private
= data
;
151 inode
->i_op
= &simple_dir_inode_operations
;
152 inode
->i_fop
= &simple_dir_operations
;
155 } else if (S_ISLNK(mode
)) {
156 inode
->i_op
= iops
? iops
: &simple_symlink_inode_operations
;
157 inode
->i_link
= data
;
161 d_instantiate(dentry
, inode
);
168 dentry
= ERR_PTR(error
);
171 simple_release_fs(&mount
, &mount_count
);
176 * securityfs_create_file - create a file in the securityfs filesystem
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
186 * @fops: a pointer to a struct file_operations that should be used for
189 * This function creates a file in securityfs with the given @name.
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).
197 * If securityfs is not enabled in the kernel, the value %-ENODEV is
200 struct dentry
*securityfs_create_file(const char *name
, umode_t mode
,
201 struct dentry
*parent
, void *data
,
202 const struct file_operations
*fops
)
204 return securityfs_create_dentry(name
, mode
, parent
, data
, fops
, NULL
);
206 EXPORT_SYMBOL_GPL(securityfs_create_file
);
209 * securityfs_create_dir - create a directory in the securityfs filesystem
211 * @name: a pointer to a string containing the name of the directory to
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.
217 * This function creates a directory in securityfs with the given @name.
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).
225 * If securityfs is not enabled in the kernel, the value %-ENODEV is
228 struct dentry
*securityfs_create_dir(const char *name
, struct dentry
*parent
)
230 return securityfs_create_file(name
, S_IFDIR
| 0755, parent
, NULL
, NULL
);
232 EXPORT_SYMBOL_GPL(securityfs_create_dir
);
235 * securityfs_create_symlink - create a symlink in the securityfs filesystem
237 * @name: a pointer to a string containing the name of the symlink to
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.
249 * This function creates a symlink in securityfs with the given @name.
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).
257 * If securityfs is not enabled in the kernel, the value %-ENODEV is
260 struct dentry
*securityfs_create_symlink(const char *name
,
261 struct dentry
*parent
,
263 const struct inode_operations
*iops
)
269 link
= kstrdup(target
, GFP_KERNEL
);
271 return ERR_PTR(-ENOMEM
);
273 dent
= securityfs_create_dentry(name
, S_IFLNK
| 0444, parent
,
280 EXPORT_SYMBOL_GPL(securityfs_create_symlink
);
283 * securityfs_remove - removes a file or directory from the securityfs filesystem
285 * @dentry: a pointer to a the dentry of the file or directory to be removed.
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.)
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.
295 void securityfs_remove(struct dentry
*dentry
)
299 if (IS_ERR_OR_NULL(dentry
))
302 dir
= d_inode(dentry
->d_parent
);
304 if (simple_positive(dentry
)) {
305 if (d_is_dir(dentry
))
306 simple_rmdir(dir
, dentry
);
308 simple_unlink(dir
, dentry
);
312 simple_release_fs(&mount
, &mount_count
);
314 EXPORT_SYMBOL_GPL(securityfs_remove
);
316 static void remove_one(struct dentry
*victim
)
318 simple_release_fs(&mount
, &mount_count
);
322 * securityfs_recursive_remove - recursively removes a file or directory
324 * @dentry: a pointer to a the dentry of the file or directory to be removed.
326 * This function recursively removes a file or directory in securityfs that was
327 * previously created with a call to another securityfs function (like
328 * securityfs_create_file() or variants thereof.)
330 void securityfs_recursive_remove(struct dentry
*dentry
)
332 if (IS_ERR_OR_NULL(dentry
))
335 simple_pin_fs(&fs_type
, &mount
, &mount_count
);
336 simple_recursive_removal(dentry
, remove_one
);
337 simple_release_fs(&mount
, &mount_count
);
339 EXPORT_SYMBOL_GPL(securityfs_recursive_remove
);
341 #ifdef CONFIG_SECURITY
342 static struct dentry
*lsm_dentry
;
343 static ssize_t
lsm_read(struct file
*filp
, char __user
*buf
, size_t count
,
346 return simple_read_from_buffer(buf
, count
, ppos
, lsm_names
,
350 static const struct file_operations lsm_ops
= {
352 .llseek
= generic_file_llseek
,
356 static int __init
securityfs_init(void)
360 retval
= sysfs_create_mount_point(kernel_kobj
, "security");
364 retval
= register_filesystem(&fs_type
);
366 sysfs_remove_mount_point(kernel_kobj
, "security");
369 #ifdef CONFIG_SECURITY
370 lsm_dentry
= securityfs_create_file("lsm", 0444, NULL
, NULL
,
375 core_initcall(securityfs_init
);