1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * eCryptfs: Linux filesystem encryption layer
4 *
5 * Copyright (C) 1997-2004 Erez Zadok
6 * Copyright (C) 2001-2004 Stony Brook University
7 * Copyright (C) 2004-2007 International Business Machines Corp.
8 * Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
9 * Michael C. Thompsion <mcthomps@us.ibm.com>
10 */
11
12#include <linux/file.h>
13#include <linux/vmalloc.h>
14#include <linux/pagemap.h>
15#include <linux/dcache.h>
16#include <linux/namei.h>
17#include <linux/mount.h>
18#include <linux/fs_stack.h>
19#include <linux/slab.h>
20#include <linux/xattr.h>
21#include <linux/posix_acl.h>
22#include <linux/posix_acl_xattr.h>
23#include <linux/fileattr.h>
24#include <asm/unaligned.h>
25#include "ecryptfs_kernel.h"
26
27static int lock_parent(struct dentry *dentry,
28 struct dentry **lower_dentry,
29 struct inode **lower_dir)
30{
31 struct dentry *lower_dir_dentry;
32
33 lower_dir_dentry = ecryptfs_dentry_to_lower(dentry: dentry->d_parent);
34 *lower_dir = d_inode(dentry: lower_dir_dentry);
35 *lower_dentry = ecryptfs_dentry_to_lower(dentry);
36
37 inode_lock_nested(inode: *lower_dir, subclass: I_MUTEX_PARENT);
38 return (*lower_dentry)->d_parent == lower_dir_dentry ? 0 : -EINVAL;
39}
40
41static int ecryptfs_inode_test(struct inode *inode, void *lower_inode)
42{
43 return ecryptfs_inode_to_lower(inode) == lower_inode;
44}
45
46static int ecryptfs_inode_set(struct inode *inode, void *opaque)
47{
48 struct inode *lower_inode = opaque;
49
50 ecryptfs_set_inode_lower(inode, lower_inode);
51 fsstack_copy_attr_all(dest: inode, src: lower_inode);
52 /* i_size will be overwritten for encrypted regular files */
53 fsstack_copy_inode_size(dst: inode, src: lower_inode);
54 inode->i_ino = lower_inode->i_ino;
55 inode->i_mapping->a_ops = &ecryptfs_aops;
56
57 if (S_ISLNK(inode->i_mode))
58 inode->i_op = &ecryptfs_symlink_iops;
59 else if (S_ISDIR(inode->i_mode))
60 inode->i_op = &ecryptfs_dir_iops;
61 else
62 inode->i_op = &ecryptfs_main_iops;
63
64 if (S_ISDIR(inode->i_mode))
65 inode->i_fop = &ecryptfs_dir_fops;
66 else if (special_file(inode->i_mode))
67 init_special_inode(inode, inode->i_mode, inode->i_rdev);
68 else
69 inode->i_fop = &ecryptfs_main_fops;
70
71 return 0;
72}
73
74static struct inode *__ecryptfs_get_inode(struct inode *lower_inode,
75 struct super_block *sb)
76{
77 struct inode *inode;
78
79 if (lower_inode->i_sb != ecryptfs_superblock_to_lower(sb))
80 return ERR_PTR(error: -EXDEV);
81 if (!igrab(lower_inode))
82 return ERR_PTR(error: -ESTALE);
83 inode = iget5_locked(sb, (unsigned long)lower_inode,
84 test: ecryptfs_inode_test, set: ecryptfs_inode_set,
85 lower_inode);
86 if (!inode) {
87 iput(lower_inode);
88 return ERR_PTR(error: -EACCES);
89 }
90 if (!(inode->i_state & I_NEW))
91 iput(lower_inode);
92
93 return inode;
94}
95
96struct inode *ecryptfs_get_inode(struct inode *lower_inode,
97 struct super_block *sb)
98{
99 struct inode *inode = __ecryptfs_get_inode(lower_inode, sb);
100
101 if (!IS_ERR(ptr: inode) && (inode->i_state & I_NEW))
102 unlock_new_inode(inode);
103
104 return inode;
105}
106
107/**
108 * ecryptfs_interpose
109 * @lower_dentry: Existing dentry in the lower filesystem
110 * @dentry: ecryptfs' dentry
111 * @sb: ecryptfs's super_block
112 *
113 * Interposes upper and lower dentries.
114 *
115 * Returns zero on success; non-zero otherwise
116 */
117static int ecryptfs_interpose(struct dentry *lower_dentry,
118 struct dentry *dentry, struct super_block *sb)
119{
120 struct inode *inode = ecryptfs_get_inode(lower_inode: d_inode(dentry: lower_dentry), sb);
121
122 if (IS_ERR(ptr: inode))
123 return PTR_ERR(ptr: inode);
124 d_instantiate(dentry, inode);
125
126 return 0;
127}
128
129static int ecryptfs_do_unlink(struct inode *dir, struct dentry *dentry,
130 struct inode *inode)
131{
132 struct dentry *lower_dentry;
133 struct inode *lower_dir;
134 int rc;
135
136 rc = lock_parent(dentry, lower_dentry: &lower_dentry, lower_dir: &lower_dir);
137 dget(dentry: lower_dentry); // don't even try to make the lower negative
138 if (!rc) {
139 if (d_unhashed(dentry: lower_dentry))
140 rc = -EINVAL;
141 else
142 rc = vfs_unlink(&nop_mnt_idmap, lower_dir, lower_dentry,
143 NULL);
144 }
145 if (rc) {
146 printk(KERN_ERR "Error in vfs_unlink; rc = [%d]\n", rc);
147 goto out_unlock;
148 }
149 fsstack_copy_attr_times(dest: dir, src: lower_dir);
150 set_nlink(inode, nlink: ecryptfs_inode_to_lower(inode)->i_nlink);
151 inode_set_ctime_to_ts(inode, ts: inode_get_ctime(inode: dir));
152out_unlock:
153 dput(lower_dentry);
154 inode_unlock(inode: lower_dir);
155 if (!rc)
156 d_drop(dentry);
157 return rc;
158}
159
160/**
161 * ecryptfs_do_create
162 * @directory_inode: inode of the new file's dentry's parent in ecryptfs
163 * @ecryptfs_dentry: New file's dentry in ecryptfs
164 * @mode: The mode of the new file
165 *
166 * Creates the underlying file and the eCryptfs inode which will link to
167 * it. It will also update the eCryptfs directory inode to mimic the
168 * stat of the lower directory inode.
169 *
170 * Returns the new eCryptfs inode on success; an ERR_PTR on error condition
171 */
172static struct inode *
173ecryptfs_do_create(struct inode *directory_inode,
174 struct dentry *ecryptfs_dentry, umode_t mode)
175{
176 int rc;
177 struct dentry *lower_dentry;
178 struct inode *lower_dir;
179 struct inode *inode;
180
181 rc = lock_parent(dentry: ecryptfs_dentry, lower_dentry: &lower_dentry, lower_dir: &lower_dir);
182 if (!rc)
183 rc = vfs_create(&nop_mnt_idmap, lower_dir,
184 lower_dentry, mode, true);
185 if (rc) {
186 printk(KERN_ERR "%s: Failure to create dentry in lower fs; "
187 "rc = [%d]\n", __func__, rc);
188 inode = ERR_PTR(error: rc);
189 goto out_lock;
190 }
191 inode = __ecryptfs_get_inode(lower_inode: d_inode(dentry: lower_dentry),
192 sb: directory_inode->i_sb);
193 if (IS_ERR(ptr: inode)) {
194 vfs_unlink(&nop_mnt_idmap, lower_dir, lower_dentry, NULL);
195 goto out_lock;
196 }
197 fsstack_copy_attr_times(dest: directory_inode, src: lower_dir);
198 fsstack_copy_inode_size(dst: directory_inode, src: lower_dir);
199out_lock:
200 inode_unlock(inode: lower_dir);
201 return inode;
202}
203
204/*
205 * ecryptfs_initialize_file
206 *
207 * Cause the file to be changed from a basic empty file to an ecryptfs
208 * file with a header and first data page.
209 *
210 * Returns zero on success
211 */
212int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry,
213 struct inode *ecryptfs_inode)
214{
215 struct ecryptfs_crypt_stat *crypt_stat =
216 &ecryptfs_inode_to_private(inode: ecryptfs_inode)->crypt_stat;
217 int rc = 0;
218
219 if (S_ISDIR(ecryptfs_inode->i_mode)) {
220 ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
221 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
222 goto out;
223 }
224 ecryptfs_printk(KERN_DEBUG, "Initializing crypto context\n");
225 rc = ecryptfs_new_file_context(ecryptfs_inode);
226 if (rc) {
227 ecryptfs_printk(KERN_ERR, "Error creating new file "
228 "context; rc = [%d]\n", rc);
229 goto out;
230 }
231 rc = ecryptfs_get_lower_file(dentry: ecryptfs_dentry, inode: ecryptfs_inode);
232 if (rc) {
233 printk(KERN_ERR "%s: Error attempting to initialize "
234 "the lower file for the dentry with name "
235 "[%pd]; rc = [%d]\n", __func__,
236 ecryptfs_dentry, rc);
237 goto out;
238 }
239 rc = ecryptfs_write_metadata(ecryptfs_dentry, ecryptfs_inode);
240 if (rc)
241 printk(KERN_ERR "Error writing headers; rc = [%d]\n", rc);
242 ecryptfs_put_lower_file(inode: ecryptfs_inode);
243out:
244 return rc;
245}
246
247/*
248 * ecryptfs_create
249 * @mode: The mode of the new file.
250 *
251 * Creates a new file.
252 *
253 * Returns zero on success; non-zero on error condition
254 */
255static int
256ecryptfs_create(struct mnt_idmap *idmap,
257 struct inode *directory_inode, struct dentry *ecryptfs_dentry,
258 umode_t mode, bool excl)
259{
260 struct inode *ecryptfs_inode;
261 int rc;
262
263 ecryptfs_inode = ecryptfs_do_create(directory_inode, ecryptfs_dentry,
264 mode);
265 if (IS_ERR(ptr: ecryptfs_inode)) {
266 ecryptfs_printk(KERN_WARNING, "Failed to create file in"
267 "lower filesystem\n");
268 rc = PTR_ERR(ptr: ecryptfs_inode);
269 goto out;
270 }
271 /* At this point, a file exists on "disk"; we need to make sure
272 * that this on disk file is prepared to be an ecryptfs file */
273 rc = ecryptfs_initialize_file(ecryptfs_dentry, ecryptfs_inode);
274 if (rc) {
275 ecryptfs_do_unlink(dir: directory_inode, dentry: ecryptfs_dentry,
276 inode: ecryptfs_inode);
277 iget_failed(ecryptfs_inode);
278 goto out;
279 }
280 d_instantiate_new(ecryptfs_dentry, ecryptfs_inode);
281out:
282 return rc;
283}
284
285static int ecryptfs_i_size_read(struct dentry *dentry, struct inode *inode)
286{
287 struct ecryptfs_crypt_stat *crypt_stat;
288 int rc;
289
290 rc = ecryptfs_get_lower_file(dentry, inode);
291 if (rc) {
292 printk(KERN_ERR "%s: Error attempting to initialize "
293 "the lower file for the dentry with name "
294 "[%pd]; rc = [%d]\n", __func__,
295 dentry, rc);
296 return rc;
297 }
298
299 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
300 /* TODO: lock for crypt_stat comparison */
301 if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED))
302 ecryptfs_set_default_sizes(crypt_stat);
303
304 rc = ecryptfs_read_and_validate_header_region(inode);
305 ecryptfs_put_lower_file(inode);
306 if (rc) {
307 rc = ecryptfs_read_and_validate_xattr_region(dentry, inode);
308 if (!rc)
309 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
310 }
311
312 /* Must return 0 to allow non-eCryptfs files to be looked up, too */
313 return 0;
314}
315
316/*
317 * ecryptfs_lookup_interpose - Dentry interposition for a lookup
318 */
319static struct dentry *ecryptfs_lookup_interpose(struct dentry *dentry,
320 struct dentry *lower_dentry)
321{
322 const struct path *path = ecryptfs_dentry_to_lower_path(dentry: dentry->d_parent);
323 struct inode *inode, *lower_inode;
324 struct ecryptfs_dentry_info *dentry_info;
325 int rc = 0;
326
327 dentry_info = kmem_cache_alloc(cachep: ecryptfs_dentry_info_cache, GFP_KERNEL);
328 if (!dentry_info) {
329 dput(lower_dentry);
330 return ERR_PTR(error: -ENOMEM);
331 }
332
333 fsstack_copy_attr_atime(dest: d_inode(dentry: dentry->d_parent),
334 src: d_inode(dentry: path->dentry));
335 BUG_ON(!d_count(lower_dentry));
336
337 ecryptfs_set_dentry_private(dentry, dentry_info);
338 dentry_info->lower_path.mnt = mntget(mnt: path->mnt);
339 dentry_info->lower_path.dentry = lower_dentry;
340
341 /*
342 * negative dentry can go positive under us here - its parent is not
343 * locked. That's OK and that could happen just as we return from
344 * ecryptfs_lookup() anyway. Just need to be careful and fetch
345 * ->d_inode only once - it's not stable here.
346 */
347 lower_inode = READ_ONCE(lower_dentry->d_inode);
348
349 if (!lower_inode) {
350 /* We want to add because we couldn't find in lower */
351 d_add(dentry, NULL);
352 return NULL;
353 }
354 inode = __ecryptfs_get_inode(lower_inode, sb: dentry->d_sb);
355 if (IS_ERR(ptr: inode)) {
356 printk(KERN_ERR "%s: Error interposing; rc = [%ld]\n",
357 __func__, PTR_ERR(inode));
358 return ERR_CAST(ptr: inode);
359 }
360 if (S_ISREG(inode->i_mode)) {
361 rc = ecryptfs_i_size_read(dentry, inode);
362 if (rc) {
363 make_bad_inode(inode);
364 return ERR_PTR(error: rc);
365 }
366 }
367
368 if (inode->i_state & I_NEW)
369 unlock_new_inode(inode);
370 return d_splice_alias(inode, dentry);
371}
372
373/**
374 * ecryptfs_lookup
375 * @ecryptfs_dir_inode: The eCryptfs directory inode
376 * @ecryptfs_dentry: The eCryptfs dentry that we are looking up
377 * @flags: lookup flags
378 *
379 * Find a file on disk. If the file does not exist, then we'll add it to the
380 * dentry cache and continue on to read it from the disk.
381 */
382static struct dentry *ecryptfs_lookup(struct inode *ecryptfs_dir_inode,
383 struct dentry *ecryptfs_dentry,
384 unsigned int flags)
385{
386 char *encrypted_and_encoded_name = NULL;
387 struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
388 struct dentry *lower_dir_dentry, *lower_dentry;
389 const char *name = ecryptfs_dentry->d_name.name;
390 size_t len = ecryptfs_dentry->d_name.len;
391 struct dentry *res;
392 int rc = 0;
393
394 lower_dir_dentry = ecryptfs_dentry_to_lower(dentry: ecryptfs_dentry->d_parent);
395
396 mount_crypt_stat = &ecryptfs_superblock_to_private(
397 sb: ecryptfs_dentry->d_sb)->mount_crypt_stat;
398 if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
399 rc = ecryptfs_encrypt_and_encode_filename(
400 encoded_name: &encrypted_and_encoded_name, encoded_name_size: &len,
401 mount_crypt_stat, name, name_size: len);
402 if (rc) {
403 printk(KERN_ERR "%s: Error attempting to encrypt and encode "
404 "filename; rc = [%d]\n", __func__, rc);
405 return ERR_PTR(error: rc);
406 }
407 name = encrypted_and_encoded_name;
408 }
409
410 lower_dentry = lookup_one_len_unlocked(name, lower_dir_dentry, len);
411 if (IS_ERR(ptr: lower_dentry)) {
412 ecryptfs_printk(KERN_DEBUG, "%s: lookup_one_len() returned "
413 "[%ld] on lower_dentry = [%s]\n", __func__,
414 PTR_ERR(lower_dentry),
415 name);
416 res = ERR_CAST(ptr: lower_dentry);
417 } else {
418 res = ecryptfs_lookup_interpose(dentry: ecryptfs_dentry, lower_dentry);
419 }
420 kfree(objp: encrypted_and_encoded_name);
421 return res;
422}
423
424static int ecryptfs_link(struct dentry *old_dentry, struct inode *dir,
425 struct dentry *new_dentry)
426{
427 struct dentry *lower_old_dentry;
428 struct dentry *lower_new_dentry;
429 struct inode *lower_dir;
430 u64 file_size_save;
431 int rc;
432
433 file_size_save = i_size_read(inode: d_inode(dentry: old_dentry));
434 lower_old_dentry = ecryptfs_dentry_to_lower(dentry: old_dentry);
435 rc = lock_parent(dentry: new_dentry, lower_dentry: &lower_new_dentry, lower_dir: &lower_dir);
436 if (!rc)
437 rc = vfs_link(lower_old_dentry, &nop_mnt_idmap, lower_dir,
438 lower_new_dentry, NULL);
439 if (rc || d_really_is_negative(dentry: lower_new_dentry))
440 goto out_lock;
441 rc = ecryptfs_interpose(lower_dentry: lower_new_dentry, dentry: new_dentry, sb: dir->i_sb);
442 if (rc)
443 goto out_lock;
444 fsstack_copy_attr_times(dest: dir, src: lower_dir);
445 fsstack_copy_inode_size(dst: dir, src: lower_dir);
446 set_nlink(inode: d_inode(dentry: old_dentry),
447 nlink: ecryptfs_inode_to_lower(inode: d_inode(dentry: old_dentry))->i_nlink);
448 i_size_write(inode: d_inode(dentry: new_dentry), i_size: file_size_save);
449out_lock:
450 inode_unlock(inode: lower_dir);
451 return rc;
452}
453
454static int ecryptfs_unlink(struct inode *dir, struct dentry *dentry)
455{
456 return ecryptfs_do_unlink(dir, dentry, inode: d_inode(dentry));
457}
458
459static int ecryptfs_symlink(struct mnt_idmap *idmap,
460 struct inode *dir, struct dentry *dentry,
461 const char *symname)
462{
463 int rc;
464 struct dentry *lower_dentry;
465 struct inode *lower_dir;
466 char *encoded_symname;
467 size_t encoded_symlen;
468 struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL;
469
470 rc = lock_parent(dentry, lower_dentry: &lower_dentry, lower_dir: &lower_dir);
471 if (rc)
472 goto out_lock;
473 mount_crypt_stat = &ecryptfs_superblock_to_private(
474 sb: dir->i_sb)->mount_crypt_stat;
475 rc = ecryptfs_encrypt_and_encode_filename(encoded_name: &encoded_symname,
476 encoded_name_size: &encoded_symlen,
477 mount_crypt_stat, name: symname,
478 strlen(symname));
479 if (rc)
480 goto out_lock;
481 rc = vfs_symlink(&nop_mnt_idmap, lower_dir, lower_dentry,
482 encoded_symname);
483 kfree(objp: encoded_symname);
484 if (rc || d_really_is_negative(dentry: lower_dentry))
485 goto out_lock;
486 rc = ecryptfs_interpose(lower_dentry, dentry, sb: dir->i_sb);
487 if (rc)
488 goto out_lock;
489 fsstack_copy_attr_times(dest: dir, src: lower_dir);
490 fsstack_copy_inode_size(dst: dir, src: lower_dir);
491out_lock:
492 inode_unlock(inode: lower_dir);
493 if (d_really_is_negative(dentry))
494 d_drop(dentry);
495 return rc;
496}
497
498static int ecryptfs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
499 struct dentry *dentry, umode_t mode)
500{
501 int rc;
502 struct dentry *lower_dentry;
503 struct inode *lower_dir;
504
505 rc = lock_parent(dentry, lower_dentry: &lower_dentry, lower_dir: &lower_dir);
506 if (!rc)
507 rc = vfs_mkdir(&nop_mnt_idmap, lower_dir,
508 lower_dentry, mode);
509 if (rc || d_really_is_negative(dentry: lower_dentry))
510 goto out;
511 rc = ecryptfs_interpose(lower_dentry, dentry, sb: dir->i_sb);
512 if (rc)
513 goto out;
514 fsstack_copy_attr_times(dest: dir, src: lower_dir);
515 fsstack_copy_inode_size(dst: dir, src: lower_dir);
516 set_nlink(inode: dir, nlink: lower_dir->i_nlink);
517out:
518 inode_unlock(inode: lower_dir);
519 if (d_really_is_negative(dentry))
520 d_drop(dentry);
521 return rc;
522}
523
524static int ecryptfs_rmdir(struct inode *dir, struct dentry *dentry)
525{
526 struct dentry *lower_dentry;
527 struct inode *lower_dir;
528 int rc;
529
530 rc = lock_parent(dentry, lower_dentry: &lower_dentry, lower_dir: &lower_dir);
531 dget(dentry: lower_dentry); // don't even try to make the lower negative
532 if (!rc) {
533 if (d_unhashed(dentry: lower_dentry))
534 rc = -EINVAL;
535 else
536 rc = vfs_rmdir(&nop_mnt_idmap, lower_dir, lower_dentry);
537 }
538 if (!rc) {
539 clear_nlink(inode: d_inode(dentry));
540 fsstack_copy_attr_times(dest: dir, src: lower_dir);
541 set_nlink(inode: dir, nlink: lower_dir->i_nlink);
542 }
543 dput(lower_dentry);
544 inode_unlock(inode: lower_dir);
545 if (!rc)
546 d_drop(dentry);
547 return rc;
548}
549
550static int
551ecryptfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
552 struct dentry *dentry, umode_t mode, dev_t dev)
553{
554 int rc;
555 struct dentry *lower_dentry;
556 struct inode *lower_dir;
557
558 rc = lock_parent(dentry, lower_dentry: &lower_dentry, lower_dir: &lower_dir);
559 if (!rc)
560 rc = vfs_mknod(&nop_mnt_idmap, lower_dir,
561 lower_dentry, mode, dev);
562 if (rc || d_really_is_negative(dentry: lower_dentry))
563 goto out;
564 rc = ecryptfs_interpose(lower_dentry, dentry, sb: dir->i_sb);
565 if (rc)
566 goto out;
567 fsstack_copy_attr_times(dest: dir, src: lower_dir);
568 fsstack_copy_inode_size(dst: dir, src: lower_dir);
569out:
570 inode_unlock(inode: lower_dir);
571 if (d_really_is_negative(dentry))
572 d_drop(dentry);
573 return rc;
574}
575
576static int
577ecryptfs_rename(struct mnt_idmap *idmap, struct inode *old_dir,
578 struct dentry *old_dentry, struct inode *new_dir,
579 struct dentry *new_dentry, unsigned int flags)
580{
581 int rc;
582 struct dentry *lower_old_dentry;
583 struct dentry *lower_new_dentry;
584 struct dentry *lower_old_dir_dentry;
585 struct dentry *lower_new_dir_dentry;
586 struct dentry *trap;
587 struct inode *target_inode;
588 struct renamedata rd = {};
589
590 if (flags)
591 return -EINVAL;
592
593 lower_old_dir_dentry = ecryptfs_dentry_to_lower(dentry: old_dentry->d_parent);
594 lower_new_dir_dentry = ecryptfs_dentry_to_lower(dentry: new_dentry->d_parent);
595
596 lower_old_dentry = ecryptfs_dentry_to_lower(dentry: old_dentry);
597 lower_new_dentry = ecryptfs_dentry_to_lower(dentry: new_dentry);
598
599 target_inode = d_inode(dentry: new_dentry);
600
601 trap = lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
602 dget(dentry: lower_new_dentry);
603 rc = -EINVAL;
604 if (lower_old_dentry->d_parent != lower_old_dir_dentry)
605 goto out_lock;
606 if (lower_new_dentry->d_parent != lower_new_dir_dentry)
607 goto out_lock;
608 if (d_unhashed(dentry: lower_old_dentry) || d_unhashed(dentry: lower_new_dentry))
609 goto out_lock;
610 /* source should not be ancestor of target */
611 if (trap == lower_old_dentry)
612 goto out_lock;
613 /* target should not be ancestor of source */
614 if (trap == lower_new_dentry) {
615 rc = -ENOTEMPTY;
616 goto out_lock;
617 }
618
619 rd.old_mnt_idmap = &nop_mnt_idmap;
620 rd.old_dir = d_inode(dentry: lower_old_dir_dentry);
621 rd.old_dentry = lower_old_dentry;
622 rd.new_mnt_idmap = &nop_mnt_idmap;
623 rd.new_dir = d_inode(dentry: lower_new_dir_dentry);
624 rd.new_dentry = lower_new_dentry;
625 rc = vfs_rename(&rd);
626 if (rc)
627 goto out_lock;
628 if (target_inode)
629 fsstack_copy_attr_all(dest: target_inode,
630 src: ecryptfs_inode_to_lower(inode: target_inode));
631 fsstack_copy_attr_all(dest: new_dir, src: d_inode(dentry: lower_new_dir_dentry));
632 if (new_dir != old_dir)
633 fsstack_copy_attr_all(dest: old_dir, src: d_inode(dentry: lower_old_dir_dentry));
634out_lock:
635 dput(lower_new_dentry);
636 unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
637 return rc;
638}
639
640static char *ecryptfs_readlink_lower(struct dentry *dentry, size_t *bufsiz)
641{
642 DEFINE_DELAYED_CALL(done);
643 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
644 const char *link;
645 char *buf;
646 int rc;
647
648 link = vfs_get_link(lower_dentry, &done);
649 if (IS_ERR(ptr: link))
650 return ERR_CAST(ptr: link);
651
652 rc = ecryptfs_decode_and_decrypt_filename(decrypted_name: &buf, decrypted_name_size: bufsiz, sb: dentry->d_sb,
653 name: link, strlen(link));
654 do_delayed_call(call: &done);
655 if (rc)
656 return ERR_PTR(error: rc);
657
658 return buf;
659}
660
661static const char *ecryptfs_get_link(struct dentry *dentry,
662 struct inode *inode,
663 struct delayed_call *done)
664{
665 size_t len;
666 char *buf;
667
668 if (!dentry)
669 return ERR_PTR(error: -ECHILD);
670
671 buf = ecryptfs_readlink_lower(dentry, bufsiz: &len);
672 if (IS_ERR(ptr: buf))
673 return buf;
674 fsstack_copy_attr_atime(dest: d_inode(dentry),
675 src: d_inode(dentry: ecryptfs_dentry_to_lower(dentry)));
676 buf[len] = '\0';
677 set_delayed_call(call: done, fn: kfree_link, arg: buf);
678 return buf;
679}
680
681/**
682 * upper_size_to_lower_size
683 * @crypt_stat: Crypt_stat associated with file
684 * @upper_size: Size of the upper file
685 *
686 * Calculate the required size of the lower file based on the
687 * specified size of the upper file. This calculation is based on the
688 * number of headers in the underlying file and the extent size.
689 *
690 * Returns Calculated size of the lower file.
691 */
692static loff_t
693upper_size_to_lower_size(struct ecryptfs_crypt_stat *crypt_stat,
694 loff_t upper_size)
695{
696 loff_t lower_size;
697
698 lower_size = ecryptfs_lower_header_size(crypt_stat);
699 if (upper_size != 0) {
700 loff_t num_extents;
701
702 num_extents = upper_size >> crypt_stat->extent_shift;
703 if (upper_size & ~crypt_stat->extent_mask)
704 num_extents++;
705 lower_size += (num_extents * crypt_stat->extent_size);
706 }
707 return lower_size;
708}
709
710/**
711 * truncate_upper
712 * @dentry: The ecryptfs layer dentry
713 * @ia: Address of the ecryptfs inode's attributes
714 * @lower_ia: Address of the lower inode's attributes
715 *
716 * Function to handle truncations modifying the size of the file. Note
717 * that the file sizes are interpolated. When expanding, we are simply
718 * writing strings of 0's out. When truncating, we truncate the upper
719 * inode and update the lower_ia according to the page index
720 * interpolations. If ATTR_SIZE is set in lower_ia->ia_valid upon return,
721 * the caller must use lower_ia in a call to notify_change() to perform
722 * the truncation of the lower inode.
723 *
724 * Returns zero on success; non-zero otherwise
725 */
726static int truncate_upper(struct dentry *dentry, struct iattr *ia,
727 struct iattr *lower_ia)
728{
729 int rc = 0;
730 struct inode *inode = d_inode(dentry);
731 struct ecryptfs_crypt_stat *crypt_stat;
732 loff_t i_size = i_size_read(inode);
733 loff_t lower_size_before_truncate;
734 loff_t lower_size_after_truncate;
735
736 if (unlikely((ia->ia_size == i_size))) {
737 lower_ia->ia_valid &= ~ATTR_SIZE;
738 return 0;
739 }
740 rc = ecryptfs_get_lower_file(dentry, inode);
741 if (rc)
742 return rc;
743 crypt_stat = &ecryptfs_inode_to_private(inode: d_inode(dentry))->crypt_stat;
744 /* Switch on growing or shrinking file */
745 if (ia->ia_size > i_size) {
746 char zero[] = { 0x00 };
747
748 lower_ia->ia_valid &= ~ATTR_SIZE;
749 /* Write a single 0 at the last position of the file;
750 * this triggers code that will fill in 0's throughout
751 * the intermediate portion of the previous end of the
752 * file and the new and of the file */
753 rc = ecryptfs_write(inode, data: zero,
754 offset: (ia->ia_size - 1), size: 1);
755 } else { /* ia->ia_size < i_size_read(inode) */
756 /* We're chopping off all the pages down to the page
757 * in which ia->ia_size is located. Fill in the end of
758 * that page from (ia->ia_size & ~PAGE_MASK) to
759 * PAGE_SIZE with zeros. */
760 size_t num_zeros = (PAGE_SIZE
761 - (ia->ia_size & ~PAGE_MASK));
762
763 if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
764 truncate_setsize(inode, newsize: ia->ia_size);
765 lower_ia->ia_size = ia->ia_size;
766 lower_ia->ia_valid |= ATTR_SIZE;
767 goto out;
768 }
769 if (num_zeros) {
770 char *zeros_virt;
771
772 zeros_virt = kzalloc(size: num_zeros, GFP_KERNEL);
773 if (!zeros_virt) {
774 rc = -ENOMEM;
775 goto out;
776 }
777 rc = ecryptfs_write(inode, data: zeros_virt,
778 offset: ia->ia_size, size: num_zeros);
779 kfree(objp: zeros_virt);
780 if (rc) {
781 printk(KERN_ERR "Error attempting to zero out "
782 "the remainder of the end page on "
783 "reducing truncate; rc = [%d]\n", rc);
784 goto out;
785 }
786 }
787 truncate_setsize(inode, newsize: ia->ia_size);
788 rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode: inode);
789 if (rc) {
790 printk(KERN_ERR "Problem with "
791 "ecryptfs_write_inode_size_to_metadata; "
792 "rc = [%d]\n", rc);
793 goto out;
794 }
795 /* We are reducing the size of the ecryptfs file, and need to
796 * know if we need to reduce the size of the lower file. */
797 lower_size_before_truncate =
798 upper_size_to_lower_size(crypt_stat, upper_size: i_size);
799 lower_size_after_truncate =
800 upper_size_to_lower_size(crypt_stat, upper_size: ia->ia_size);
801 if (lower_size_after_truncate < lower_size_before_truncate) {
802 lower_ia->ia_size = lower_size_after_truncate;
803 lower_ia->ia_valid |= ATTR_SIZE;
804 } else
805 lower_ia->ia_valid &= ~ATTR_SIZE;
806 }
807out:
808 ecryptfs_put_lower_file(inode);
809 return rc;
810}
811
812static int ecryptfs_inode_newsize_ok(struct inode *inode, loff_t offset)
813{
814 struct ecryptfs_crypt_stat *crypt_stat;
815 loff_t lower_oldsize, lower_newsize;
816
817 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
818 lower_oldsize = upper_size_to_lower_size(crypt_stat,
819 upper_size: i_size_read(inode));
820 lower_newsize = upper_size_to_lower_size(crypt_stat, upper_size: offset);
821 if (lower_newsize > lower_oldsize) {
822 /*
823 * The eCryptfs inode and the new *lower* size are mixed here
824 * because we may not have the lower i_mutex held and/or it may
825 * not be appropriate to call inode_newsize_ok() with inodes
826 * from other filesystems.
827 */
828 return inode_newsize_ok(inode, offset: lower_newsize);
829 }
830
831 return 0;
832}
833
834/**
835 * ecryptfs_truncate
836 * @dentry: The ecryptfs layer dentry
837 * @new_length: The length to expand the file to
838 *
839 * Simple function that handles the truncation of an eCryptfs inode and
840 * its corresponding lower inode.
841 *
842 * Returns zero on success; non-zero otherwise
843 */
844int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
845{
846 struct iattr ia = { .ia_valid = ATTR_SIZE, .ia_size = new_length };
847 struct iattr lower_ia = { .ia_valid = 0 };
848 int rc;
849
850 rc = ecryptfs_inode_newsize_ok(inode: d_inode(dentry), offset: new_length);
851 if (rc)
852 return rc;
853
854 rc = truncate_upper(dentry, ia: &ia, lower_ia: &lower_ia);
855 if (!rc && lower_ia.ia_valid & ATTR_SIZE) {
856 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
857
858 inode_lock(inode: d_inode(dentry: lower_dentry));
859 rc = notify_change(&nop_mnt_idmap, lower_dentry,
860 &lower_ia, NULL);
861 inode_unlock(inode: d_inode(dentry: lower_dentry));
862 }
863 return rc;
864}
865
866static int
867ecryptfs_permission(struct mnt_idmap *idmap, struct inode *inode,
868 int mask)
869{
870 return inode_permission(&nop_mnt_idmap,
871 ecryptfs_inode_to_lower(inode), mask);
872}
873
874/**
875 * ecryptfs_setattr
876 * @idmap: idmap of the target mount
877 * @dentry: dentry handle to the inode to modify
878 * @ia: Structure with flags of what to change and values
879 *
880 * Updates the metadata of an inode. If the update is to the size
881 * i.e. truncation, then ecryptfs_truncate will handle the size modification
882 * of both the ecryptfs inode and the lower inode.
883 *
884 * All other metadata changes will be passed right to the lower filesystem,
885 * and we will just update our inode to look like the lower.
886 */
887static int ecryptfs_setattr(struct mnt_idmap *idmap,
888 struct dentry *dentry, struct iattr *ia)
889{
890 int rc = 0;
891 struct dentry *lower_dentry;
892 struct iattr lower_ia;
893 struct inode *inode;
894 struct inode *lower_inode;
895 struct ecryptfs_crypt_stat *crypt_stat;
896
897 crypt_stat = &ecryptfs_inode_to_private(inode: d_inode(dentry))->crypt_stat;
898 if (!(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED)) {
899 rc = ecryptfs_init_crypt_stat(crypt_stat);
900 if (rc)
901 return rc;
902 }
903 inode = d_inode(dentry);
904 lower_inode = ecryptfs_inode_to_lower(inode);
905 lower_dentry = ecryptfs_dentry_to_lower(dentry);
906 mutex_lock(&crypt_stat->cs_mutex);
907 if (d_is_dir(dentry))
908 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
909 else if (d_is_reg(dentry)
910 && (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
911 || !(crypt_stat->flags & ECRYPTFS_KEY_VALID))) {
912 struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
913
914 mount_crypt_stat = &ecryptfs_superblock_to_private(
915 sb: dentry->d_sb)->mount_crypt_stat;
916 rc = ecryptfs_get_lower_file(dentry, inode);
917 if (rc) {
918 mutex_unlock(lock: &crypt_stat->cs_mutex);
919 goto out;
920 }
921 rc = ecryptfs_read_metadata(ecryptfs_dentry: dentry);
922 ecryptfs_put_lower_file(inode);
923 if (rc) {
924 if (!(mount_crypt_stat->flags
925 & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
926 rc = -EIO;
927 printk(KERN_WARNING "Either the lower file "
928 "is not in a valid eCryptfs format, "
929 "or the key could not be retrieved. "
930 "Plaintext passthrough mode is not "
931 "enabled; returning -EIO\n");
932 mutex_unlock(lock: &crypt_stat->cs_mutex);
933 goto out;
934 }
935 rc = 0;
936 crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
937 | ECRYPTFS_ENCRYPTED);
938 }
939 }
940 mutex_unlock(lock: &crypt_stat->cs_mutex);
941
942 rc = setattr_prepare(&nop_mnt_idmap, dentry, ia);
943 if (rc)
944 goto out;
945 if (ia->ia_valid & ATTR_SIZE) {
946 rc = ecryptfs_inode_newsize_ok(inode, offset: ia->ia_size);
947 if (rc)
948 goto out;
949 }
950
951 memcpy(&lower_ia, ia, sizeof(lower_ia));
952 if (ia->ia_valid & ATTR_FILE)
953 lower_ia.ia_file = ecryptfs_file_to_lower(file: ia->ia_file);
954 if (ia->ia_valid & ATTR_SIZE) {
955 rc = truncate_upper(dentry, ia, lower_ia: &lower_ia);
956 if (rc < 0)
957 goto out;
958 }
959
960 /*
961 * mode change is for clearing setuid/setgid bits. Allow lower fs
962 * to interpret this in its own way.
963 */
964 if (lower_ia.ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
965 lower_ia.ia_valid &= ~ATTR_MODE;
966
967 inode_lock(inode: d_inode(dentry: lower_dentry));
968 rc = notify_change(&nop_mnt_idmap, lower_dentry, &lower_ia, NULL);
969 inode_unlock(inode: d_inode(dentry: lower_dentry));
970out:
971 fsstack_copy_attr_all(dest: inode, src: lower_inode);
972 return rc;
973}
974
975static int ecryptfs_getattr_link(struct mnt_idmap *idmap,
976 const struct path *path, struct kstat *stat,
977 u32 request_mask, unsigned int flags)
978{
979 struct dentry *dentry = path->dentry;
980 struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
981 int rc = 0;
982
983 mount_crypt_stat = &ecryptfs_superblock_to_private(
984 sb: dentry->d_sb)->mount_crypt_stat;
985 generic_fillattr(&nop_mnt_idmap, request_mask, d_inode(dentry), stat);
986 if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
987 char *target;
988 size_t targetsiz;
989
990 target = ecryptfs_readlink_lower(dentry, bufsiz: &targetsiz);
991 if (!IS_ERR(ptr: target)) {
992 kfree(objp: target);
993 stat->size = targetsiz;
994 } else {
995 rc = PTR_ERR(ptr: target);
996 }
997 }
998 return rc;
999}
1000
1001static int ecryptfs_getattr(struct mnt_idmap *idmap,
1002 const struct path *path, struct kstat *stat,
1003 u32 request_mask, unsigned int flags)
1004{
1005 struct dentry *dentry = path->dentry;
1006 struct kstat lower_stat;
1007 int rc;
1008
1009 rc = vfs_getattr(ecryptfs_dentry_to_lower_path(dentry), &lower_stat,
1010 request_mask, flags);
1011 if (!rc) {
1012 fsstack_copy_attr_all(dest: d_inode(dentry),
1013 src: ecryptfs_inode_to_lower(inode: d_inode(dentry)));
1014 generic_fillattr(&nop_mnt_idmap, request_mask,
1015 d_inode(dentry), stat);
1016 stat->blocks = lower_stat.blocks;
1017 }
1018 return rc;
1019}
1020
1021int
1022ecryptfs_setxattr(struct dentry *dentry, struct inode *inode,
1023 const char *name, const void *value,
1024 size_t size, int flags)
1025{
1026 int rc;
1027 struct dentry *lower_dentry;
1028 struct inode *lower_inode;
1029
1030 lower_dentry = ecryptfs_dentry_to_lower(dentry);
1031 lower_inode = d_inode(dentry: lower_dentry);
1032 if (!(lower_inode->i_opflags & IOP_XATTR)) {
1033 rc = -EOPNOTSUPP;
1034 goto out;
1035 }
1036 inode_lock(inode: lower_inode);
1037 rc = __vfs_setxattr_locked(&nop_mnt_idmap, lower_dentry, name, value, size, flags, NULL);
1038 inode_unlock(inode: lower_inode);
1039 if (!rc && inode)
1040 fsstack_copy_attr_all(dest: inode, src: lower_inode);
1041out:
1042 return rc;
1043}
1044
1045ssize_t
1046ecryptfs_getxattr_lower(struct dentry *lower_dentry, struct inode *lower_inode,
1047 const char *name, void *value, size_t size)
1048{
1049 int rc;
1050
1051 if (!(lower_inode->i_opflags & IOP_XATTR)) {
1052 rc = -EOPNOTSUPP;
1053 goto out;
1054 }
1055 inode_lock(inode: lower_inode);
1056 rc = __vfs_getxattr(lower_dentry, lower_inode, name, value, size);
1057 inode_unlock(inode: lower_inode);
1058out:
1059 return rc;
1060}
1061
1062static ssize_t
1063ecryptfs_getxattr(struct dentry *dentry, struct inode *inode,
1064 const char *name, void *value, size_t size)
1065{
1066 return ecryptfs_getxattr_lower(lower_dentry: ecryptfs_dentry_to_lower(dentry),
1067 lower_inode: ecryptfs_inode_to_lower(inode),
1068 name, value, size);
1069}
1070
1071static ssize_t
1072ecryptfs_listxattr(struct dentry *dentry, char *list, size_t size)
1073{
1074 int rc = 0;
1075 struct dentry *lower_dentry;
1076
1077 lower_dentry = ecryptfs_dentry_to_lower(dentry);
1078 if (!d_inode(dentry: lower_dentry)->i_op->listxattr) {
1079 rc = -EOPNOTSUPP;
1080 goto out;
1081 }
1082 inode_lock(inode: d_inode(dentry: lower_dentry));
1083 rc = d_inode(dentry: lower_dentry)->i_op->listxattr(lower_dentry, list, size);
1084 inode_unlock(inode: d_inode(dentry: lower_dentry));
1085out:
1086 return rc;
1087}
1088
1089static int ecryptfs_removexattr(struct dentry *dentry, struct inode *inode,
1090 const char *name)
1091{
1092 int rc;
1093 struct dentry *lower_dentry;
1094 struct inode *lower_inode;
1095
1096 lower_dentry = ecryptfs_dentry_to_lower(dentry);
1097 lower_inode = ecryptfs_inode_to_lower(inode);
1098 if (!(lower_inode->i_opflags & IOP_XATTR)) {
1099 rc = -EOPNOTSUPP;
1100 goto out;
1101 }
1102 inode_lock(inode: lower_inode);
1103 rc = __vfs_removexattr(&nop_mnt_idmap, lower_dentry, name);
1104 inode_unlock(inode: lower_inode);
1105out:
1106 return rc;
1107}
1108
1109static int ecryptfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
1110{
1111 return vfs_fileattr_get(dentry: ecryptfs_dentry_to_lower(dentry), fa);
1112}
1113
1114static int ecryptfs_fileattr_set(struct mnt_idmap *idmap,
1115 struct dentry *dentry, struct fileattr *fa)
1116{
1117 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
1118 int rc;
1119
1120 rc = vfs_fileattr_set(idmap: &nop_mnt_idmap, dentry: lower_dentry, fa);
1121 fsstack_copy_attr_all(dest: d_inode(dentry), src: d_inode(dentry: lower_dentry));
1122
1123 return rc;
1124}
1125
1126static struct posix_acl *ecryptfs_get_acl(struct mnt_idmap *idmap,
1127 struct dentry *dentry, int type)
1128{
1129 return vfs_get_acl(idmap, dentry: ecryptfs_dentry_to_lower(dentry),
1130 acl_name: posix_acl_xattr_name(type));
1131}
1132
1133static int ecryptfs_set_acl(struct mnt_idmap *idmap,
1134 struct dentry *dentry, struct posix_acl *acl,
1135 int type)
1136{
1137 int rc;
1138 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
1139 struct inode *lower_inode = d_inode(dentry: lower_dentry);
1140
1141 rc = vfs_set_acl(idmap: &nop_mnt_idmap, dentry: lower_dentry,
1142 acl_name: posix_acl_xattr_name(type), kacl: acl);
1143 if (!rc)
1144 fsstack_copy_attr_all(dest: d_inode(dentry), src: lower_inode);
1145 return rc;
1146}
1147
1148const struct inode_operations ecryptfs_symlink_iops = {
1149 .get_link = ecryptfs_get_link,
1150 .permission = ecryptfs_permission,
1151 .setattr = ecryptfs_setattr,
1152 .getattr = ecryptfs_getattr_link,
1153 .listxattr = ecryptfs_listxattr,
1154};
1155
1156const struct inode_operations ecryptfs_dir_iops = {
1157 .create = ecryptfs_create,
1158 .lookup = ecryptfs_lookup,
1159 .link = ecryptfs_link,
1160 .unlink = ecryptfs_unlink,
1161 .symlink = ecryptfs_symlink,
1162 .mkdir = ecryptfs_mkdir,
1163 .rmdir = ecryptfs_rmdir,
1164 .mknod = ecryptfs_mknod,
1165 .rename = ecryptfs_rename,
1166 .permission = ecryptfs_permission,
1167 .setattr = ecryptfs_setattr,
1168 .listxattr = ecryptfs_listxattr,
1169 .fileattr_get = ecryptfs_fileattr_get,
1170 .fileattr_set = ecryptfs_fileattr_set,
1171 .get_acl = ecryptfs_get_acl,
1172 .set_acl = ecryptfs_set_acl,
1173};
1174
1175const struct inode_operations ecryptfs_main_iops = {
1176 .permission = ecryptfs_permission,
1177 .setattr = ecryptfs_setattr,
1178 .getattr = ecryptfs_getattr,
1179 .listxattr = ecryptfs_listxattr,
1180 .fileattr_get = ecryptfs_fileattr_get,
1181 .fileattr_set = ecryptfs_fileattr_set,
1182 .get_acl = ecryptfs_get_acl,
1183 .set_acl = ecryptfs_set_acl,
1184};
1185
1186static int ecryptfs_xattr_get(const struct xattr_handler *handler,
1187 struct dentry *dentry, struct inode *inode,
1188 const char *name, void *buffer, size_t size)
1189{
1190 return ecryptfs_getxattr(dentry, inode, name, value: buffer, size);
1191}
1192
1193static int ecryptfs_xattr_set(const struct xattr_handler *handler,
1194 struct mnt_idmap *idmap,
1195 struct dentry *dentry, struct inode *inode,
1196 const char *name, const void *value, size_t size,
1197 int flags)
1198{
1199 if (value)
1200 return ecryptfs_setxattr(dentry, inode, name, value, size, flags);
1201 else {
1202 BUG_ON(flags != XATTR_REPLACE);
1203 return ecryptfs_removexattr(dentry, inode, name);
1204 }
1205}
1206
1207static const struct xattr_handler ecryptfs_xattr_handler = {
1208 .prefix = "", /* match anything */
1209 .get = ecryptfs_xattr_get,
1210 .set = ecryptfs_xattr_set,
1211};
1212
1213const struct xattr_handler * const ecryptfs_xattr_handlers[] = {
1214 &ecryptfs_xattr_handler,
1215 NULL
1216};
1217

source code of linux/fs/ecryptfs/inode.c