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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * fs/kernfs/inode.c - kernfs inode implementation
4 *
5 * Copyright (c) 2001-3 Patrick Mochel
6 * Copyright (c) 2007 SUSE Linux Products GmbH
7 * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
8 */
9
10#include <linux/pagemap.h>
11#include <linux/backing-dev.h>
12#include <linux/capability.h>
13#include <linux/errno.h>
14#include <linux/slab.h>
15#include <linux/xattr.h>
16#include <linux/security.h>
17
18#include "kernfs-internal.h"
19
20static const struct address_space_operations kernfs_aops = {
21 .readpage = simple_readpage,
22 .write_begin = simple_write_begin,
23 .write_end = simple_write_end,
24};
25
26static const struct inode_operations kernfs_iops = {
27 .permission = kernfs_iop_permission,
28 .setattr = kernfs_iop_setattr,
29 .getattr = kernfs_iop_getattr,
30 .listxattr = kernfs_iop_listxattr,
31};
32
33static struct kernfs_iattrs *__kernfs_iattrs(struct kernfs_node *kn, int alloc)
34{
35 static DEFINE_MUTEX(iattr_mutex);
36 struct kernfs_iattrs *ret;
37
38 mutex_lock(&iattr_mutex);
39
40 if (kn->iattr || !alloc)
41 goto out_unlock;
42
43 kn->iattr = kmem_cache_zalloc(kernfs_iattrs_cache, GFP_KERNEL);
44 if (!kn->iattr)
45 goto out_unlock;
46
47 /* assign default attributes */
48 kn->iattr->ia_uid = GLOBAL_ROOT_UID;
49 kn->iattr->ia_gid = GLOBAL_ROOT_GID;
50
51 ktime_get_real_ts64(&kn->iattr->ia_atime);
52 kn->iattr->ia_mtime = kn->iattr->ia_atime;
53 kn->iattr->ia_ctime = kn->iattr->ia_atime;
54
55 simple_xattrs_init(&kn->iattr->xattrs);
56out_unlock:
57 ret = kn->iattr;
58 mutex_unlock(&iattr_mutex);
59 return ret;
60}
61
62static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
63{
64 return __kernfs_iattrs(kn, 1);
65}
66
67static struct kernfs_iattrs *kernfs_iattrs_noalloc(struct kernfs_node *kn)
68{
69 return __kernfs_iattrs(kn, 0);
70}
71
72int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
73{
74 struct kernfs_iattrs *attrs;
75 unsigned int ia_valid = iattr->ia_valid;
76
77 attrs = kernfs_iattrs(kn);
78 if (!attrs)
79 return -ENOMEM;
80
81 if (ia_valid & ATTR_UID)
82 attrs->ia_uid = iattr->ia_uid;
83 if (ia_valid & ATTR_GID)
84 attrs->ia_gid = iattr->ia_gid;
85 if (ia_valid & ATTR_ATIME)
86 attrs->ia_atime = iattr->ia_atime;
87 if (ia_valid & ATTR_MTIME)
88 attrs->ia_mtime = iattr->ia_mtime;
89 if (ia_valid & ATTR_CTIME)
90 attrs->ia_ctime = iattr->ia_ctime;
91 if (ia_valid & ATTR_MODE)
92 kn->mode = iattr->ia_mode;
93 return 0;
94}
95
96/**
97 * kernfs_setattr - set iattr on a node
98 * @kn: target node
99 * @iattr: iattr to set
100 *
101 * Returns 0 on success, -errno on failure.
102 */
103int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
104{
105 int ret;
106
107 mutex_lock(&kernfs_mutex);
108 ret = __kernfs_setattr(kn, iattr);
109 mutex_unlock(&kernfs_mutex);
110 return ret;
111}
112
113int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr)
114{
115 struct inode *inode = d_inode(dentry);
116 struct kernfs_node *kn = inode->i_private;
117 int error;
118
119 if (!kn)
120 return -EINVAL;
121
122 mutex_lock(&kernfs_mutex);
123 error = setattr_prepare(dentry, iattr);
124 if (error)
125 goto out;
126
127 error = __kernfs_setattr(kn, iattr);
128 if (error)
129 goto out;
130
131 /* this ignores size changes */
132 setattr_copy(inode, iattr);
133
134out:
135 mutex_unlock(&kernfs_mutex);
136 return error;
137}
138
139ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
140{
141 struct kernfs_node *kn = kernfs_dentry_node(dentry);
142 struct kernfs_iattrs *attrs;
143
144 attrs = kernfs_iattrs(kn);
145 if (!attrs)
146 return -ENOMEM;
147
148 return simple_xattr_list(d_inode(dentry), &attrs->xattrs, buf, size);
149}
150
151static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
152{
153 inode->i_mode = mode;
154 inode->i_atime = inode->i_mtime =
155 inode->i_ctime = current_time(inode);
156}
157
158static inline void set_inode_attr(struct inode *inode,
159 struct kernfs_iattrs *attrs)
160{
161 inode->i_uid = attrs->ia_uid;
162 inode->i_gid = attrs->ia_gid;
163 inode->i_atime = timestamp_truncate(attrs->ia_atime, inode);
164 inode->i_mtime = timestamp_truncate(attrs->ia_mtime, inode);
165 inode->i_ctime = timestamp_truncate(attrs->ia_ctime, inode);
166}
167
168static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
169{
170 struct kernfs_iattrs *attrs = kn->iattr;
171
172 inode->i_mode = kn->mode;
173 if (attrs)
174 /*
175 * kernfs_node has non-default attributes get them from
176 * persistent copy in kernfs_node.
177 */
178 set_inode_attr(inode, attrs);
179
180 if (kernfs_type(kn) == KERNFS_DIR)
181 set_nlink(inode, kn->dir.subdirs + 2);
182}
183
184int kernfs_iop_getattr(const struct path *path, struct kstat *stat,
185 u32 request_mask, unsigned int query_flags)
186{
187 struct inode *inode = d_inode(path->dentry);
188 struct kernfs_node *kn = inode->i_private;
189
190 mutex_lock(&kernfs_mutex);
191 kernfs_refresh_inode(kn, inode);
192 mutex_unlock(&kernfs_mutex);
193
194 generic_fillattr(inode, stat);
195 return 0;
196}
197
198static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode)
199{
200 kernfs_get(kn);
201 inode->i_private = kn;
202 inode->i_mapping->a_ops = &kernfs_aops;
203 inode->i_op = &kernfs_iops;
204 inode->i_generation = kn->id.generation;
205
206 set_default_inode_attr(inode, kn->mode);
207 kernfs_refresh_inode(kn, inode);
208
209 /* initialize inode according to type */
210 switch (kernfs_type(kn)) {
211 case KERNFS_DIR:
212 inode->i_op = &kernfs_dir_iops;
213 inode->i_fop = &kernfs_dir_fops;
214 if (kn->flags & KERNFS_EMPTY_DIR)
215 make_empty_dir_inode(inode);
216 break;
217 case KERNFS_FILE:
218 inode->i_size = kn->attr.size;
219 inode->i_fop = &kernfs_file_fops;
220 break;
221 case KERNFS_LINK:
222 inode->i_op = &kernfs_symlink_iops;
223 break;
224 default:
225 BUG();
226 }
227
228 unlock_new_inode(inode);
229}
230
231/**
232 * kernfs_get_inode - get inode for kernfs_node
233 * @sb: super block
234 * @kn: kernfs_node to allocate inode for
235 *
236 * Get inode for @kn. If such inode doesn't exist, a new inode is
237 * allocated and basics are initialized. New inode is returned
238 * locked.
239 *
240 * LOCKING:
241 * Kernel thread context (may sleep).
242 *
243 * RETURNS:
244 * Pointer to allocated inode on success, NULL on failure.
245 */
246struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
247{
248 struct inode *inode;
249
250 inode = iget_locked(sb, kn->id.ino);
251 if (inode && (inode->i_state & I_NEW))
252 kernfs_init_inode(kn, inode);
253
254 return inode;
255}
256
257/*
258 * The kernfs_node serves as both an inode and a directory entry for
259 * kernfs. To prevent the kernfs inode numbers from being freed
260 * prematurely we take a reference to kernfs_node from the kernfs inode. A
261 * super_operations.evict_inode() implementation is needed to drop that
262 * reference upon inode destruction.
263 */
264void kernfs_evict_inode(struct inode *inode)
265{
266 struct kernfs_node *kn = inode->i_private;
267
268 truncate_inode_pages_final(&inode->i_data);
269 clear_inode(inode);
270 kernfs_put(kn);
271}
272
273int kernfs_iop_permission(struct inode *inode, int mask)
274{
275 struct kernfs_node *kn;
276
277 if (mask & MAY_NOT_BLOCK)
278 return -ECHILD;
279
280 kn = inode->i_private;
281
282 mutex_lock(&kernfs_mutex);
283 kernfs_refresh_inode(kn, inode);
284 mutex_unlock(&kernfs_mutex);
285
286 return generic_permission(inode, mask);
287}
288
289int kernfs_xattr_get(struct kernfs_node *kn, const char *name,
290 void *value, size_t size)
291{
292 struct kernfs_iattrs *attrs = kernfs_iattrs_noalloc(kn);
293 if (!attrs)
294 return -ENODATA;
295
296 return simple_xattr_get(&attrs->xattrs, name, value, size);
297}
298
299int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
300 const void *value, size_t size, int flags)
301{
302 struct kernfs_iattrs *attrs = kernfs_iattrs(kn);
303 if (!attrs)
304 return -ENOMEM;
305
306 return simple_xattr_set(&attrs->xattrs, name, value, size, flags);
307}
308
309static int kernfs_vfs_xattr_get(const struct xattr_handler *handler,
310 struct dentry *unused, struct inode *inode,
311 const char *suffix, void *value, size_t size)
312{
313 const char *name = xattr_full_name(handler, suffix);
314 struct kernfs_node *kn = inode->i_private;
315
316 return kernfs_xattr_get(kn, name, value, size);
317}
318
319static int kernfs_vfs_xattr_set(const struct xattr_handler *handler,
320 struct dentry *unused, struct inode *inode,
321 const char *suffix, const void *value,
322 size_t size, int flags)
323{
324 const char *name = xattr_full_name(handler, suffix);
325 struct kernfs_node *kn = inode->i_private;
326
327 return kernfs_xattr_set(kn, name, value, size, flags);
328}
329
330static const struct xattr_handler kernfs_trusted_xattr_handler = {
331 .prefix = XATTR_TRUSTED_PREFIX,
332 .get = kernfs_vfs_xattr_get,
333 .set = kernfs_vfs_xattr_set,
334};
335
336static const struct xattr_handler kernfs_security_xattr_handler = {
337 .prefix = XATTR_SECURITY_PREFIX,
338 .get = kernfs_vfs_xattr_get,
339 .set = kernfs_vfs_xattr_set,
340};
341
342const struct xattr_handler *kernfs_xattr_handlers[] = {
343 &kernfs_trusted_xattr_handler,
344 &kernfs_security_xattr_handler,
345 NULL
346};
1/*
2 * fs/kernfs/inode.c - kernfs inode implementation
3 *
4 * Copyright (c) 2001-3 Patrick Mochel
5 * Copyright (c) 2007 SUSE Linux Products GmbH
6 * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
7 *
8 * This file is released under the GPLv2.
9 */
10
11#include <linux/pagemap.h>
12#include <linux/backing-dev.h>
13#include <linux/capability.h>
14#include <linux/errno.h>
15#include <linux/slab.h>
16#include <linux/xattr.h>
17#include <linux/security.h>
18
19#include "kernfs-internal.h"
20
21static const struct address_space_operations kernfs_aops = {
22 .readpage = simple_readpage,
23 .write_begin = simple_write_begin,
24 .write_end = simple_write_end,
25};
26
27static struct backing_dev_info kernfs_bdi = {
28 .name = "kernfs",
29 .ra_pages = 0, /* No readahead */
30 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
31};
32
33static const struct inode_operations kernfs_iops = {
34 .permission = kernfs_iop_permission,
35 .setattr = kernfs_iop_setattr,
36 .getattr = kernfs_iop_getattr,
37 .setxattr = kernfs_iop_setxattr,
38 .removexattr = kernfs_iop_removexattr,
39 .getxattr = kernfs_iop_getxattr,
40 .listxattr = kernfs_iop_listxattr,
41};
42
43void __init kernfs_inode_init(void)
44{
45 if (bdi_init(&kernfs_bdi))
46 panic("failed to init kernfs_bdi");
47}
48
49static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
50{
51 static DEFINE_MUTEX(iattr_mutex);
52 struct kernfs_iattrs *ret;
53 struct iattr *iattrs;
54
55 mutex_lock(&iattr_mutex);
56
57 if (kn->iattr)
58 goto out_unlock;
59
60 kn->iattr = kzalloc(sizeof(struct kernfs_iattrs), GFP_KERNEL);
61 if (!kn->iattr)
62 goto out_unlock;
63 iattrs = &kn->iattr->ia_iattr;
64
65 /* assign default attributes */
66 iattrs->ia_mode = kn->mode;
67 iattrs->ia_uid = GLOBAL_ROOT_UID;
68 iattrs->ia_gid = GLOBAL_ROOT_GID;
69 iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;
70
71 simple_xattrs_init(&kn->iattr->xattrs);
72out_unlock:
73 ret = kn->iattr;
74 mutex_unlock(&iattr_mutex);
75 return ret;
76}
77
78static int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
79{
80 struct kernfs_iattrs *attrs;
81 struct iattr *iattrs;
82 unsigned int ia_valid = iattr->ia_valid;
83
84 attrs = kernfs_iattrs(kn);
85 if (!attrs)
86 return -ENOMEM;
87
88 iattrs = &attrs->ia_iattr;
89
90 if (ia_valid & ATTR_UID)
91 iattrs->ia_uid = iattr->ia_uid;
92 if (ia_valid & ATTR_GID)
93 iattrs->ia_gid = iattr->ia_gid;
94 if (ia_valid & ATTR_ATIME)
95 iattrs->ia_atime = iattr->ia_atime;
96 if (ia_valid & ATTR_MTIME)
97 iattrs->ia_mtime = iattr->ia_mtime;
98 if (ia_valid & ATTR_CTIME)
99 iattrs->ia_ctime = iattr->ia_ctime;
100 if (ia_valid & ATTR_MODE) {
101 umode_t mode = iattr->ia_mode;
102 iattrs->ia_mode = kn->mode = mode;
103 }
104 return 0;
105}
106
107/**
108 * kernfs_setattr - set iattr on a node
109 * @kn: target node
110 * @iattr: iattr to set
111 *
112 * Returns 0 on success, -errno on failure.
113 */
114int kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
115{
116 int ret;
117
118 mutex_lock(&kernfs_mutex);
119 ret = __kernfs_setattr(kn, iattr);
120 mutex_unlock(&kernfs_mutex);
121 return ret;
122}
123
124int kernfs_iop_setattr(struct dentry *dentry, struct iattr *iattr)
125{
126 struct inode *inode = dentry->d_inode;
127 struct kernfs_node *kn = dentry->d_fsdata;
128 int error;
129
130 if (!kn)
131 return -EINVAL;
132
133 mutex_lock(&kernfs_mutex);
134 error = inode_change_ok(inode, iattr);
135 if (error)
136 goto out;
137
138 error = __kernfs_setattr(kn, iattr);
139 if (error)
140 goto out;
141
142 /* this ignores size changes */
143 setattr_copy(inode, iattr);
144
145out:
146 mutex_unlock(&kernfs_mutex);
147 return error;
148}
149
150static int kernfs_node_setsecdata(struct kernfs_node *kn, void **secdata,
151 u32 *secdata_len)
152{
153 struct kernfs_iattrs *attrs;
154 void *old_secdata;
155 size_t old_secdata_len;
156
157 attrs = kernfs_iattrs(kn);
158 if (!attrs)
159 return -ENOMEM;
160
161 old_secdata = attrs->ia_secdata;
162 old_secdata_len = attrs->ia_secdata_len;
163
164 attrs->ia_secdata = *secdata;
165 attrs->ia_secdata_len = *secdata_len;
166
167 *secdata = old_secdata;
168 *secdata_len = old_secdata_len;
169 return 0;
170}
171
172int kernfs_iop_setxattr(struct dentry *dentry, const char *name,
173 const void *value, size_t size, int flags)
174{
175 struct kernfs_node *kn = dentry->d_fsdata;
176 struct kernfs_iattrs *attrs;
177 void *secdata;
178 int error;
179 u32 secdata_len = 0;
180
181 attrs = kernfs_iattrs(kn);
182 if (!attrs)
183 return -ENOMEM;
184
185 if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
186 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
187 error = security_inode_setsecurity(dentry->d_inode, suffix,
188 value, size, flags);
189 if (error)
190 return error;
191 error = security_inode_getsecctx(dentry->d_inode,
192 &secdata, &secdata_len);
193 if (error)
194 return error;
195
196 mutex_lock(&kernfs_mutex);
197 error = kernfs_node_setsecdata(kn, &secdata, &secdata_len);
198 mutex_unlock(&kernfs_mutex);
199
200 if (secdata)
201 security_release_secctx(secdata, secdata_len);
202 return error;
203 } else if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) {
204 return simple_xattr_set(&attrs->xattrs, name, value, size,
205 flags);
206 }
207
208 return -EINVAL;
209}
210
211int kernfs_iop_removexattr(struct dentry *dentry, const char *name)
212{
213 struct kernfs_node *kn = dentry->d_fsdata;
214 struct kernfs_iattrs *attrs;
215
216 attrs = kernfs_iattrs(kn);
217 if (!attrs)
218 return -ENOMEM;
219
220 return simple_xattr_remove(&attrs->xattrs, name);
221}
222
223ssize_t kernfs_iop_getxattr(struct dentry *dentry, const char *name, void *buf,
224 size_t size)
225{
226 struct kernfs_node *kn = dentry->d_fsdata;
227 struct kernfs_iattrs *attrs;
228
229 attrs = kernfs_iattrs(kn);
230 if (!attrs)
231 return -ENOMEM;
232
233 return simple_xattr_get(&attrs->xattrs, name, buf, size);
234}
235
236ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
237{
238 struct kernfs_node *kn = dentry->d_fsdata;
239 struct kernfs_iattrs *attrs;
240
241 attrs = kernfs_iattrs(kn);
242 if (!attrs)
243 return -ENOMEM;
244
245 return simple_xattr_list(&attrs->xattrs, buf, size);
246}
247
248static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
249{
250 inode->i_mode = mode;
251 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
252}
253
254static inline void set_inode_attr(struct inode *inode, struct iattr *iattr)
255{
256 inode->i_uid = iattr->ia_uid;
257 inode->i_gid = iattr->ia_gid;
258 inode->i_atime = iattr->ia_atime;
259 inode->i_mtime = iattr->ia_mtime;
260 inode->i_ctime = iattr->ia_ctime;
261}
262
263static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
264{
265 struct kernfs_iattrs *attrs = kn->iattr;
266
267 inode->i_mode = kn->mode;
268 if (attrs) {
269 /*
270 * kernfs_node has non-default attributes get them from
271 * persistent copy in kernfs_node.
272 */
273 set_inode_attr(inode, &attrs->ia_iattr);
274 security_inode_notifysecctx(inode, attrs->ia_secdata,
275 attrs->ia_secdata_len);
276 }
277
278 if (kernfs_type(kn) == KERNFS_DIR)
279 set_nlink(inode, kn->dir.subdirs + 2);
280}
281
282int kernfs_iop_getattr(struct vfsmount *mnt, struct dentry *dentry,
283 struct kstat *stat)
284{
285 struct kernfs_node *kn = dentry->d_fsdata;
286 struct inode *inode = dentry->d_inode;
287
288 mutex_lock(&kernfs_mutex);
289 kernfs_refresh_inode(kn, inode);
290 mutex_unlock(&kernfs_mutex);
291
292 generic_fillattr(inode, stat);
293 return 0;
294}
295
296static void kernfs_init_inode(struct kernfs_node *kn, struct inode *inode)
297{
298 kernfs_get(kn);
299 inode->i_private = kn;
300 inode->i_mapping->a_ops = &kernfs_aops;
301 inode->i_mapping->backing_dev_info = &kernfs_bdi;
302 inode->i_op = &kernfs_iops;
303
304 set_default_inode_attr(inode, kn->mode);
305 kernfs_refresh_inode(kn, inode);
306
307 /* initialize inode according to type */
308 switch (kernfs_type(kn)) {
309 case KERNFS_DIR:
310 inode->i_op = &kernfs_dir_iops;
311 inode->i_fop = &kernfs_dir_fops;
312 break;
313 case KERNFS_FILE:
314 inode->i_size = kn->attr.size;
315 inode->i_fop = &kernfs_file_fops;
316 break;
317 case KERNFS_LINK:
318 inode->i_op = &kernfs_symlink_iops;
319 break;
320 default:
321 BUG();
322 }
323
324 unlock_new_inode(inode);
325}
326
327/**
328 * kernfs_get_inode - get inode for kernfs_node
329 * @sb: super block
330 * @kn: kernfs_node to allocate inode for
331 *
332 * Get inode for @kn. If such inode doesn't exist, a new inode is
333 * allocated and basics are initialized. New inode is returned
334 * locked.
335 *
336 * LOCKING:
337 * Kernel thread context (may sleep).
338 *
339 * RETURNS:
340 * Pointer to allocated inode on success, NULL on failure.
341 */
342struct inode *kernfs_get_inode(struct super_block *sb, struct kernfs_node *kn)
343{
344 struct inode *inode;
345
346 inode = iget_locked(sb, kn->ino);
347 if (inode && (inode->i_state & I_NEW))
348 kernfs_init_inode(kn, inode);
349
350 return inode;
351}
352
353/*
354 * The kernfs_node serves as both an inode and a directory entry for
355 * kernfs. To prevent the kernfs inode numbers from being freed
356 * prematurely we take a reference to kernfs_node from the kernfs inode. A
357 * super_operations.evict_inode() implementation is needed to drop that
358 * reference upon inode destruction.
359 */
360void kernfs_evict_inode(struct inode *inode)
361{
362 struct kernfs_node *kn = inode->i_private;
363
364 truncate_inode_pages_final(&inode->i_data);
365 clear_inode(inode);
366 kernfs_put(kn);
367}
368
369int kernfs_iop_permission(struct inode *inode, int mask)
370{
371 struct kernfs_node *kn;
372
373 if (mask & MAY_NOT_BLOCK)
374 return -ECHILD;
375
376 kn = inode->i_private;
377
378 mutex_lock(&kernfs_mutex);
379 kernfs_refresh_inode(kn, inode);
380 mutex_unlock(&kernfs_mutex);
381
382 return generic_permission(inode, mask);
383}