xref: /openbmc/linux/fs/ecryptfs/inode.c (revision c4a7b9b5)
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/fileattr.h>
22 #include <asm/unaligned.h>
23 #include "ecryptfs_kernel.h"
24 
25 static int lock_parent(struct dentry *dentry,
26 		       struct dentry **lower_dentry,
27 		       struct inode **lower_dir)
28 {
29 	struct dentry *lower_dir_dentry;
30 
31 	lower_dir_dentry = ecryptfs_dentry_to_lower(dentry->d_parent);
32 	*lower_dir = d_inode(lower_dir_dentry);
33 	*lower_dentry = ecryptfs_dentry_to_lower(dentry);
34 
35 	inode_lock_nested(*lower_dir, I_MUTEX_PARENT);
36 	return (*lower_dentry)->d_parent == lower_dir_dentry ? 0 : -EINVAL;
37 }
38 
39 static int ecryptfs_inode_test(struct inode *inode, void *lower_inode)
40 {
41 	return ecryptfs_inode_to_lower(inode) == lower_inode;
42 }
43 
44 static int ecryptfs_inode_set(struct inode *inode, void *opaque)
45 {
46 	struct inode *lower_inode = opaque;
47 
48 	ecryptfs_set_inode_lower(inode, lower_inode);
49 	fsstack_copy_attr_all(inode, lower_inode);
50 	/* i_size will be overwritten for encrypted regular files */
51 	fsstack_copy_inode_size(inode, lower_inode);
52 	inode->i_ino = lower_inode->i_ino;
53 	inode->i_mapping->a_ops = &ecryptfs_aops;
54 
55 	if (S_ISLNK(inode->i_mode))
56 		inode->i_op = &ecryptfs_symlink_iops;
57 	else if (S_ISDIR(inode->i_mode))
58 		inode->i_op = &ecryptfs_dir_iops;
59 	else
60 		inode->i_op = &ecryptfs_main_iops;
61 
62 	if (S_ISDIR(inode->i_mode))
63 		inode->i_fop = &ecryptfs_dir_fops;
64 	else if (special_file(inode->i_mode))
65 		init_special_inode(inode, inode->i_mode, inode->i_rdev);
66 	else
67 		inode->i_fop = &ecryptfs_main_fops;
68 
69 	return 0;
70 }
71 
72 static struct inode *__ecryptfs_get_inode(struct inode *lower_inode,
73 					  struct super_block *sb)
74 {
75 	struct inode *inode;
76 
77 	if (lower_inode->i_sb != ecryptfs_superblock_to_lower(sb))
78 		return ERR_PTR(-EXDEV);
79 	if (!igrab(lower_inode))
80 		return ERR_PTR(-ESTALE);
81 	inode = iget5_locked(sb, (unsigned long)lower_inode,
82 			     ecryptfs_inode_test, ecryptfs_inode_set,
83 			     lower_inode);
84 	if (!inode) {
85 		iput(lower_inode);
86 		return ERR_PTR(-EACCES);
87 	}
88 	if (!(inode->i_state & I_NEW))
89 		iput(lower_inode);
90 
91 	return inode;
92 }
93 
94 struct inode *ecryptfs_get_inode(struct inode *lower_inode,
95 				 struct super_block *sb)
96 {
97 	struct inode *inode = __ecryptfs_get_inode(lower_inode, sb);
98 
99 	if (!IS_ERR(inode) && (inode->i_state & I_NEW))
100 		unlock_new_inode(inode);
101 
102 	return inode;
103 }
104 
105 /**
106  * ecryptfs_interpose
107  * @lower_dentry: Existing dentry in the lower filesystem
108  * @dentry: ecryptfs' dentry
109  * @sb: ecryptfs's super_block
110  *
111  * Interposes upper and lower dentries.
112  *
113  * Returns zero on success; non-zero otherwise
114  */
115 static int ecryptfs_interpose(struct dentry *lower_dentry,
116 			      struct dentry *dentry, struct super_block *sb)
117 {
118 	struct inode *inode = ecryptfs_get_inode(d_inode(lower_dentry), sb);
119 
120 	if (IS_ERR(inode))
121 		return PTR_ERR(inode);
122 	d_instantiate(dentry, inode);
123 
124 	return 0;
125 }
126 
127 static int ecryptfs_do_unlink(struct inode *dir, struct dentry *dentry,
128 			      struct inode *inode)
129 {
130 	struct dentry *lower_dentry;
131 	struct inode *lower_dir;
132 	int rc;
133 
134 	rc = lock_parent(dentry, &lower_dentry, &lower_dir);
135 	dget(lower_dentry);	// don't even try to make the lower negative
136 	if (!rc) {
137 		if (d_unhashed(lower_dentry))
138 			rc = -EINVAL;
139 		else
140 			rc = vfs_unlink(&init_user_ns, lower_dir, lower_dentry,
141 					NULL);
142 	}
143 	if (rc) {
144 		printk(KERN_ERR "Error in vfs_unlink; rc = [%d]\n", rc);
145 		goto out_unlock;
146 	}
147 	fsstack_copy_attr_times(dir, lower_dir);
148 	set_nlink(inode, ecryptfs_inode_to_lower(inode)->i_nlink);
149 	inode->i_ctime = dir->i_ctime;
150 out_unlock:
151 	dput(lower_dentry);
152 	inode_unlock(lower_dir);
153 	if (!rc)
154 		d_drop(dentry);
155 	return rc;
156 }
157 
158 /**
159  * ecryptfs_do_create
160  * @directory_inode: inode of the new file's dentry's parent in ecryptfs
161  * @ecryptfs_dentry: New file's dentry in ecryptfs
162  * @mode: The mode of the new file
163  *
164  * Creates the underlying file and the eCryptfs inode which will link to
165  * it. It will also update the eCryptfs directory inode to mimic the
166  * stat of the lower directory inode.
167  *
168  * Returns the new eCryptfs inode on success; an ERR_PTR on error condition
169  */
170 static struct inode *
171 ecryptfs_do_create(struct inode *directory_inode,
172 		   struct dentry *ecryptfs_dentry, umode_t mode)
173 {
174 	int rc;
175 	struct dentry *lower_dentry;
176 	struct inode *lower_dir;
177 	struct inode *inode;
178 
179 	rc = lock_parent(ecryptfs_dentry, &lower_dentry, &lower_dir);
180 	if (!rc)
181 		rc = vfs_create(&init_user_ns, lower_dir,
182 				lower_dentry, mode, true);
183 	if (rc) {
184 		printk(KERN_ERR "%s: Failure to create dentry in lower fs; "
185 		       "rc = [%d]\n", __func__, rc);
186 		inode = ERR_PTR(rc);
187 		goto out_lock;
188 	}
189 	inode = __ecryptfs_get_inode(d_inode(lower_dentry),
190 				     directory_inode->i_sb);
191 	if (IS_ERR(inode)) {
192 		vfs_unlink(&init_user_ns, lower_dir, lower_dentry, NULL);
193 		goto out_lock;
194 	}
195 	fsstack_copy_attr_times(directory_inode, lower_dir);
196 	fsstack_copy_inode_size(directory_inode, lower_dir);
197 out_lock:
198 	inode_unlock(lower_dir);
199 	return inode;
200 }
201 
202 /*
203  * ecryptfs_initialize_file
204  *
205  * Cause the file to be changed from a basic empty file to an ecryptfs
206  * file with a header and first data page.
207  *
208  * Returns zero on success
209  */
210 int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry,
211 			     struct inode *ecryptfs_inode)
212 {
213 	struct ecryptfs_crypt_stat *crypt_stat =
214 		&ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
215 	int rc = 0;
216 
217 	if (S_ISDIR(ecryptfs_inode->i_mode)) {
218 		ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
219 		crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
220 		goto out;
221 	}
222 	ecryptfs_printk(KERN_DEBUG, "Initializing crypto context\n");
223 	rc = ecryptfs_new_file_context(ecryptfs_inode);
224 	if (rc) {
225 		ecryptfs_printk(KERN_ERR, "Error creating new file "
226 				"context; rc = [%d]\n", rc);
227 		goto out;
228 	}
229 	rc = ecryptfs_get_lower_file(ecryptfs_dentry, ecryptfs_inode);
230 	if (rc) {
231 		printk(KERN_ERR "%s: Error attempting to initialize "
232 			"the lower file for the dentry with name "
233 			"[%pd]; rc = [%d]\n", __func__,
234 			ecryptfs_dentry, rc);
235 		goto out;
236 	}
237 	rc = ecryptfs_write_metadata(ecryptfs_dentry, ecryptfs_inode);
238 	if (rc)
239 		printk(KERN_ERR "Error writing headers; rc = [%d]\n", rc);
240 	ecryptfs_put_lower_file(ecryptfs_inode);
241 out:
242 	return rc;
243 }
244 
245 /*
246  * ecryptfs_create
247  * @mode: The mode of the new file.
248  *
249  * Creates a new file.
250  *
251  * Returns zero on success; non-zero on error condition
252  */
253 static int
254 ecryptfs_create(struct user_namespace *mnt_userns,
255 		struct inode *directory_inode, struct dentry *ecryptfs_dentry,
256 		umode_t mode, bool excl)
257 {
258 	struct inode *ecryptfs_inode;
259 	int rc;
260 
261 	ecryptfs_inode = ecryptfs_do_create(directory_inode, ecryptfs_dentry,
262 					    mode);
263 	if (IS_ERR(ecryptfs_inode)) {
264 		ecryptfs_printk(KERN_WARNING, "Failed to create file in"
265 				"lower filesystem\n");
266 		rc = PTR_ERR(ecryptfs_inode);
267 		goto out;
268 	}
269 	/* At this point, a file exists on "disk"; we need to make sure
270 	 * that this on disk file is prepared to be an ecryptfs file */
271 	rc = ecryptfs_initialize_file(ecryptfs_dentry, ecryptfs_inode);
272 	if (rc) {
273 		ecryptfs_do_unlink(directory_inode, ecryptfs_dentry,
274 				   ecryptfs_inode);
275 		iget_failed(ecryptfs_inode);
276 		goto out;
277 	}
278 	d_instantiate_new(ecryptfs_dentry, ecryptfs_inode);
279 out:
280 	return rc;
281 }
282 
283 static int ecryptfs_i_size_read(struct dentry *dentry, struct inode *inode)
284 {
285 	struct ecryptfs_crypt_stat *crypt_stat;
286 	int rc;
287 
288 	rc = ecryptfs_get_lower_file(dentry, inode);
289 	if (rc) {
290 		printk(KERN_ERR "%s: Error attempting to initialize "
291 			"the lower file for the dentry with name "
292 			"[%pd]; rc = [%d]\n", __func__,
293 			dentry, rc);
294 		return rc;
295 	}
296 
297 	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
298 	/* TODO: lock for crypt_stat comparison */
299 	if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED))
300 		ecryptfs_set_default_sizes(crypt_stat);
301 
302 	rc = ecryptfs_read_and_validate_header_region(inode);
303 	ecryptfs_put_lower_file(inode);
304 	if (rc) {
305 		rc = ecryptfs_read_and_validate_xattr_region(dentry, inode);
306 		if (!rc)
307 			crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
308 	}
309 
310 	/* Must return 0 to allow non-eCryptfs files to be looked up, too */
311 	return 0;
312 }
313 
314 /*
315  * ecryptfs_lookup_interpose - Dentry interposition for a lookup
316  */
317 static struct dentry *ecryptfs_lookup_interpose(struct dentry *dentry,
318 				     struct dentry *lower_dentry)
319 {
320 	const struct path *path = ecryptfs_dentry_to_lower_path(dentry->d_parent);
321 	struct inode *inode, *lower_inode;
322 	struct ecryptfs_dentry_info *dentry_info;
323 	int rc = 0;
324 
325 	dentry_info = kmem_cache_alloc(ecryptfs_dentry_info_cache, GFP_KERNEL);
326 	if (!dentry_info) {
327 		dput(lower_dentry);
328 		return ERR_PTR(-ENOMEM);
329 	}
330 
331 	fsstack_copy_attr_atime(d_inode(dentry->d_parent),
332 				d_inode(path->dentry));
333 	BUG_ON(!d_count(lower_dentry));
334 
335 	ecryptfs_set_dentry_private(dentry, dentry_info);
336 	dentry_info->lower_path.mnt = mntget(path->mnt);
337 	dentry_info->lower_path.dentry = lower_dentry;
338 
339 	/*
340 	 * negative dentry can go positive under us here - its parent is not
341 	 * locked.  That's OK and that could happen just as we return from
342 	 * ecryptfs_lookup() anyway.  Just need to be careful and fetch
343 	 * ->d_inode only once - it's not stable here.
344 	 */
345 	lower_inode = READ_ONCE(lower_dentry->d_inode);
346 
347 	if (!lower_inode) {
348 		/* We want to add because we couldn't find in lower */
349 		d_add(dentry, NULL);
350 		return NULL;
351 	}
352 	inode = __ecryptfs_get_inode(lower_inode, dentry->d_sb);
353 	if (IS_ERR(inode)) {
354 		printk(KERN_ERR "%s: Error interposing; rc = [%ld]\n",
355 		       __func__, PTR_ERR(inode));
356 		return ERR_CAST(inode);
357 	}
358 	if (S_ISREG(inode->i_mode)) {
359 		rc = ecryptfs_i_size_read(dentry, inode);
360 		if (rc) {
361 			make_bad_inode(inode);
362 			return ERR_PTR(rc);
363 		}
364 	}
365 
366 	if (inode->i_state & I_NEW)
367 		unlock_new_inode(inode);
368 	return d_splice_alias(inode, dentry);
369 }
370 
371 /**
372  * ecryptfs_lookup
373  * @ecryptfs_dir_inode: The eCryptfs directory inode
374  * @ecryptfs_dentry: The eCryptfs dentry that we are looking up
375  * @flags: lookup flags
376  *
377  * Find a file on disk. If the file does not exist, then we'll add it to the
378  * dentry cache and continue on to read it from the disk.
379  */
380 static struct dentry *ecryptfs_lookup(struct inode *ecryptfs_dir_inode,
381 				      struct dentry *ecryptfs_dentry,
382 				      unsigned int flags)
383 {
384 	char *encrypted_and_encoded_name = NULL;
385 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
386 	struct dentry *lower_dir_dentry, *lower_dentry;
387 	const char *name = ecryptfs_dentry->d_name.name;
388 	size_t len = ecryptfs_dentry->d_name.len;
389 	struct dentry *res;
390 	int rc = 0;
391 
392 	lower_dir_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry->d_parent);
393 
394 	mount_crypt_stat = &ecryptfs_superblock_to_private(
395 				ecryptfs_dentry->d_sb)->mount_crypt_stat;
396 	if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
397 		rc = ecryptfs_encrypt_and_encode_filename(
398 			&encrypted_and_encoded_name, &len,
399 			mount_crypt_stat, name, len);
400 		if (rc) {
401 			printk(KERN_ERR "%s: Error attempting to encrypt and encode "
402 			       "filename; rc = [%d]\n", __func__, rc);
403 			return ERR_PTR(rc);
404 		}
405 		name = encrypted_and_encoded_name;
406 	}
407 
408 	lower_dentry = lookup_one_len_unlocked(name, lower_dir_dentry, len);
409 	if (IS_ERR(lower_dentry)) {
410 		ecryptfs_printk(KERN_DEBUG, "%s: lookup_one_len() returned "
411 				"[%ld] on lower_dentry = [%s]\n", __func__,
412 				PTR_ERR(lower_dentry),
413 				name);
414 		res = ERR_CAST(lower_dentry);
415 	} else {
416 		res = ecryptfs_lookup_interpose(ecryptfs_dentry, lower_dentry);
417 	}
418 	kfree(encrypted_and_encoded_name);
419 	return res;
420 }
421 
422 static int ecryptfs_link(struct dentry *old_dentry, struct inode *dir,
423 			 struct dentry *new_dentry)
424 {
425 	struct dentry *lower_old_dentry;
426 	struct dentry *lower_new_dentry;
427 	struct inode *lower_dir;
428 	u64 file_size_save;
429 	int rc;
430 
431 	file_size_save = i_size_read(d_inode(old_dentry));
432 	lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
433 	rc = lock_parent(new_dentry, &lower_new_dentry, &lower_dir);
434 	if (!rc)
435 		rc = vfs_link(lower_old_dentry, &init_user_ns, lower_dir,
436 			      lower_new_dentry, NULL);
437 	if (rc || d_really_is_negative(lower_new_dentry))
438 		goto out_lock;
439 	rc = ecryptfs_interpose(lower_new_dentry, new_dentry, dir->i_sb);
440 	if (rc)
441 		goto out_lock;
442 	fsstack_copy_attr_times(dir, lower_dir);
443 	fsstack_copy_inode_size(dir, lower_dir);
444 	set_nlink(d_inode(old_dentry),
445 		  ecryptfs_inode_to_lower(d_inode(old_dentry))->i_nlink);
446 	i_size_write(d_inode(new_dentry), file_size_save);
447 out_lock:
448 	inode_unlock(lower_dir);
449 	return rc;
450 }
451 
452 static int ecryptfs_unlink(struct inode *dir, struct dentry *dentry)
453 {
454 	return ecryptfs_do_unlink(dir, dentry, d_inode(dentry));
455 }
456 
457 static int ecryptfs_symlink(struct user_namespace *mnt_userns,
458 			    struct inode *dir, struct dentry *dentry,
459 			    const char *symname)
460 {
461 	int rc;
462 	struct dentry *lower_dentry;
463 	struct inode *lower_dir;
464 	char *encoded_symname;
465 	size_t encoded_symlen;
466 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL;
467 
468 	rc = lock_parent(dentry, &lower_dentry, &lower_dir);
469 	if (rc)
470 		goto out_lock;
471 	mount_crypt_stat = &ecryptfs_superblock_to_private(
472 		dir->i_sb)->mount_crypt_stat;
473 	rc = ecryptfs_encrypt_and_encode_filename(&encoded_symname,
474 						  &encoded_symlen,
475 						  mount_crypt_stat, symname,
476 						  strlen(symname));
477 	if (rc)
478 		goto out_lock;
479 	rc = vfs_symlink(&init_user_ns, lower_dir, lower_dentry,
480 			 encoded_symname);
481 	kfree(encoded_symname);
482 	if (rc || d_really_is_negative(lower_dentry))
483 		goto out_lock;
484 	rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
485 	if (rc)
486 		goto out_lock;
487 	fsstack_copy_attr_times(dir, lower_dir);
488 	fsstack_copy_inode_size(dir, lower_dir);
489 out_lock:
490 	inode_unlock(lower_dir);
491 	if (d_really_is_negative(dentry))
492 		d_drop(dentry);
493 	return rc;
494 }
495 
496 static int ecryptfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
497 			  struct dentry *dentry, umode_t mode)
498 {
499 	int rc;
500 	struct dentry *lower_dentry;
501 	struct inode *lower_dir;
502 
503 	rc = lock_parent(dentry, &lower_dentry, &lower_dir);
504 	if (!rc)
505 		rc = vfs_mkdir(&init_user_ns, lower_dir,
506 			       lower_dentry, mode);
507 	if (rc || d_really_is_negative(lower_dentry))
508 		goto out;
509 	rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
510 	if (rc)
511 		goto out;
512 	fsstack_copy_attr_times(dir, lower_dir);
513 	fsstack_copy_inode_size(dir, lower_dir);
514 	set_nlink(dir, lower_dir->i_nlink);
515 out:
516 	inode_unlock(lower_dir);
517 	if (d_really_is_negative(dentry))
518 		d_drop(dentry);
519 	return rc;
520 }
521 
522 static int ecryptfs_rmdir(struct inode *dir, struct dentry *dentry)
523 {
524 	struct dentry *lower_dentry;
525 	struct inode *lower_dir;
526 	int rc;
527 
528 	rc = lock_parent(dentry, &lower_dentry, &lower_dir);
529 	dget(lower_dentry);	// don't even try to make the lower negative
530 	if (!rc) {
531 		if (d_unhashed(lower_dentry))
532 			rc = -EINVAL;
533 		else
534 			rc = vfs_rmdir(&init_user_ns, lower_dir, lower_dentry);
535 	}
536 	if (!rc) {
537 		clear_nlink(d_inode(dentry));
538 		fsstack_copy_attr_times(dir, lower_dir);
539 		set_nlink(dir, lower_dir->i_nlink);
540 	}
541 	dput(lower_dentry);
542 	inode_unlock(lower_dir);
543 	if (!rc)
544 		d_drop(dentry);
545 	return rc;
546 }
547 
548 static int
549 ecryptfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
550 	       struct dentry *dentry, umode_t mode, dev_t dev)
551 {
552 	int rc;
553 	struct dentry *lower_dentry;
554 	struct inode *lower_dir;
555 
556 	rc = lock_parent(dentry, &lower_dentry, &lower_dir);
557 	if (!rc)
558 		rc = vfs_mknod(&init_user_ns, lower_dir,
559 			       lower_dentry, mode, dev);
560 	if (rc || d_really_is_negative(lower_dentry))
561 		goto out;
562 	rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
563 	if (rc)
564 		goto out;
565 	fsstack_copy_attr_times(dir, lower_dir);
566 	fsstack_copy_inode_size(dir, lower_dir);
567 out:
568 	inode_unlock(lower_dir);
569 	if (d_really_is_negative(dentry))
570 		d_drop(dentry);
571 	return rc;
572 }
573 
574 static int
575 ecryptfs_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
576 		struct dentry *old_dentry, struct inode *new_dir,
577 		struct dentry *new_dentry, unsigned int flags)
578 {
579 	int rc;
580 	struct dentry *lower_old_dentry;
581 	struct dentry *lower_new_dentry;
582 	struct dentry *lower_old_dir_dentry;
583 	struct dentry *lower_new_dir_dentry;
584 	struct dentry *trap;
585 	struct inode *target_inode;
586 	struct renamedata rd = {};
587 
588 	if (flags)
589 		return -EINVAL;
590 
591 	lower_old_dir_dentry = ecryptfs_dentry_to_lower(old_dentry->d_parent);
592 	lower_new_dir_dentry = ecryptfs_dentry_to_lower(new_dentry->d_parent);
593 
594 	lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
595 	lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
596 
597 	target_inode = d_inode(new_dentry);
598 
599 	trap = lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
600 	dget(lower_new_dentry);
601 	rc = -EINVAL;
602 	if (lower_old_dentry->d_parent != lower_old_dir_dentry)
603 		goto out_lock;
604 	if (lower_new_dentry->d_parent != lower_new_dir_dentry)
605 		goto out_lock;
606 	if (d_unhashed(lower_old_dentry) || d_unhashed(lower_new_dentry))
607 		goto out_lock;
608 	/* source should not be ancestor of target */
609 	if (trap == lower_old_dentry)
610 		goto out_lock;
611 	/* target should not be ancestor of source */
612 	if (trap == lower_new_dentry) {
613 		rc = -ENOTEMPTY;
614 		goto out_lock;
615 	}
616 
617 	rd.old_mnt_userns	= &init_user_ns;
618 	rd.old_dir		= d_inode(lower_old_dir_dentry);
619 	rd.old_dentry		= lower_old_dentry;
620 	rd.new_mnt_userns	= &init_user_ns;
621 	rd.new_dir		= d_inode(lower_new_dir_dentry);
622 	rd.new_dentry		= lower_new_dentry;
623 	rc = vfs_rename(&rd);
624 	if (rc)
625 		goto out_lock;
626 	if (target_inode)
627 		fsstack_copy_attr_all(target_inode,
628 				      ecryptfs_inode_to_lower(target_inode));
629 	fsstack_copy_attr_all(new_dir, d_inode(lower_new_dir_dentry));
630 	if (new_dir != old_dir)
631 		fsstack_copy_attr_all(old_dir, d_inode(lower_old_dir_dentry));
632 out_lock:
633 	dput(lower_new_dentry);
634 	unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
635 	return rc;
636 }
637 
638 static char *ecryptfs_readlink_lower(struct dentry *dentry, size_t *bufsiz)
639 {
640 	DEFINE_DELAYED_CALL(done);
641 	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
642 	const char *link;
643 	char *buf;
644 	int rc;
645 
646 	link = vfs_get_link(lower_dentry, &done);
647 	if (IS_ERR(link))
648 		return ERR_CAST(link);
649 
650 	rc = ecryptfs_decode_and_decrypt_filename(&buf, bufsiz, dentry->d_sb,
651 						  link, strlen(link));
652 	do_delayed_call(&done);
653 	if (rc)
654 		return ERR_PTR(rc);
655 
656 	return buf;
657 }
658 
659 static const char *ecryptfs_get_link(struct dentry *dentry,
660 				     struct inode *inode,
661 				     struct delayed_call *done)
662 {
663 	size_t len;
664 	char *buf;
665 
666 	if (!dentry)
667 		return ERR_PTR(-ECHILD);
668 
669 	buf = ecryptfs_readlink_lower(dentry, &len);
670 	if (IS_ERR(buf))
671 		return buf;
672 	fsstack_copy_attr_atime(d_inode(dentry),
673 				d_inode(ecryptfs_dentry_to_lower(dentry)));
674 	buf[len] = '\0';
675 	set_delayed_call(done, kfree_link, buf);
676 	return buf;
677 }
678 
679 /**
680  * upper_size_to_lower_size
681  * @crypt_stat: Crypt_stat associated with file
682  * @upper_size: Size of the upper file
683  *
684  * Calculate the required size of the lower file based on the
685  * specified size of the upper file. This calculation is based on the
686  * number of headers in the underlying file and the extent size.
687  *
688  * Returns Calculated size of the lower file.
689  */
690 static loff_t
691 upper_size_to_lower_size(struct ecryptfs_crypt_stat *crypt_stat,
692 			 loff_t upper_size)
693 {
694 	loff_t lower_size;
695 
696 	lower_size = ecryptfs_lower_header_size(crypt_stat);
697 	if (upper_size != 0) {
698 		loff_t num_extents;
699 
700 		num_extents = upper_size >> crypt_stat->extent_shift;
701 		if (upper_size & ~crypt_stat->extent_mask)
702 			num_extents++;
703 		lower_size += (num_extents * crypt_stat->extent_size);
704 	}
705 	return lower_size;
706 }
707 
708 /**
709  * truncate_upper
710  * @dentry: The ecryptfs layer dentry
711  * @ia: Address of the ecryptfs inode's attributes
712  * @lower_ia: Address of the lower inode's attributes
713  *
714  * Function to handle truncations modifying the size of the file. Note
715  * that the file sizes are interpolated. When expanding, we are simply
716  * writing strings of 0's out. When truncating, we truncate the upper
717  * inode and update the lower_ia according to the page index
718  * interpolations. If ATTR_SIZE is set in lower_ia->ia_valid upon return,
719  * the caller must use lower_ia in a call to notify_change() to perform
720  * the truncation of the lower inode.
721  *
722  * Returns zero on success; non-zero otherwise
723  */
724 static int truncate_upper(struct dentry *dentry, struct iattr *ia,
725 			  struct iattr *lower_ia)
726 {
727 	int rc = 0;
728 	struct inode *inode = d_inode(dentry);
729 	struct ecryptfs_crypt_stat *crypt_stat;
730 	loff_t i_size = i_size_read(inode);
731 	loff_t lower_size_before_truncate;
732 	loff_t lower_size_after_truncate;
733 
734 	if (unlikely((ia->ia_size == i_size))) {
735 		lower_ia->ia_valid &= ~ATTR_SIZE;
736 		return 0;
737 	}
738 	rc = ecryptfs_get_lower_file(dentry, inode);
739 	if (rc)
740 		return rc;
741 	crypt_stat = &ecryptfs_inode_to_private(d_inode(dentry))->crypt_stat;
742 	/* Switch on growing or shrinking file */
743 	if (ia->ia_size > i_size) {
744 		char zero[] = { 0x00 };
745 
746 		lower_ia->ia_valid &= ~ATTR_SIZE;
747 		/* Write a single 0 at the last position of the file;
748 		 * this triggers code that will fill in 0's throughout
749 		 * the intermediate portion of the previous end of the
750 		 * file and the new and of the file */
751 		rc = ecryptfs_write(inode, zero,
752 				    (ia->ia_size - 1), 1);
753 	} else { /* ia->ia_size < i_size_read(inode) */
754 		/* We're chopping off all the pages down to the page
755 		 * in which ia->ia_size is located. Fill in the end of
756 		 * that page from (ia->ia_size & ~PAGE_MASK) to
757 		 * PAGE_SIZE with zeros. */
758 		size_t num_zeros = (PAGE_SIZE
759 				    - (ia->ia_size & ~PAGE_MASK));
760 
761 		if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
762 			truncate_setsize(inode, ia->ia_size);
763 			lower_ia->ia_size = ia->ia_size;
764 			lower_ia->ia_valid |= ATTR_SIZE;
765 			goto out;
766 		}
767 		if (num_zeros) {
768 			char *zeros_virt;
769 
770 			zeros_virt = kzalloc(num_zeros, GFP_KERNEL);
771 			if (!zeros_virt) {
772 				rc = -ENOMEM;
773 				goto out;
774 			}
775 			rc = ecryptfs_write(inode, zeros_virt,
776 					    ia->ia_size, num_zeros);
777 			kfree(zeros_virt);
778 			if (rc) {
779 				printk(KERN_ERR "Error attempting to zero out "
780 				       "the remainder of the end page on "
781 				       "reducing truncate; rc = [%d]\n", rc);
782 				goto out;
783 			}
784 		}
785 		truncate_setsize(inode, ia->ia_size);
786 		rc = ecryptfs_write_inode_size_to_metadata(inode);
787 		if (rc) {
788 			printk(KERN_ERR	"Problem with "
789 			       "ecryptfs_write_inode_size_to_metadata; "
790 			       "rc = [%d]\n", rc);
791 			goto out;
792 		}
793 		/* We are reducing the size of the ecryptfs file, and need to
794 		 * know if we need to reduce the size of the lower file. */
795 		lower_size_before_truncate =
796 		    upper_size_to_lower_size(crypt_stat, i_size);
797 		lower_size_after_truncate =
798 		    upper_size_to_lower_size(crypt_stat, ia->ia_size);
799 		if (lower_size_after_truncate < lower_size_before_truncate) {
800 			lower_ia->ia_size = lower_size_after_truncate;
801 			lower_ia->ia_valid |= ATTR_SIZE;
802 		} else
803 			lower_ia->ia_valid &= ~ATTR_SIZE;
804 	}
805 out:
806 	ecryptfs_put_lower_file(inode);
807 	return rc;
808 }
809 
810 static int ecryptfs_inode_newsize_ok(struct inode *inode, loff_t offset)
811 {
812 	struct ecryptfs_crypt_stat *crypt_stat;
813 	loff_t lower_oldsize, lower_newsize;
814 
815 	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
816 	lower_oldsize = upper_size_to_lower_size(crypt_stat,
817 						 i_size_read(inode));
818 	lower_newsize = upper_size_to_lower_size(crypt_stat, offset);
819 	if (lower_newsize > lower_oldsize) {
820 		/*
821 		 * The eCryptfs inode and the new *lower* size are mixed here
822 		 * because we may not have the lower i_mutex held and/or it may
823 		 * not be appropriate to call inode_newsize_ok() with inodes
824 		 * from other filesystems.
825 		 */
826 		return inode_newsize_ok(inode, lower_newsize);
827 	}
828 
829 	return 0;
830 }
831 
832 /**
833  * ecryptfs_truncate
834  * @dentry: The ecryptfs layer dentry
835  * @new_length: The length to expand the file to
836  *
837  * Simple function that handles the truncation of an eCryptfs inode and
838  * its corresponding lower inode.
839  *
840  * Returns zero on success; non-zero otherwise
841  */
842 int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
843 {
844 	struct iattr ia = { .ia_valid = ATTR_SIZE, .ia_size = new_length };
845 	struct iattr lower_ia = { .ia_valid = 0 };
846 	int rc;
847 
848 	rc = ecryptfs_inode_newsize_ok(d_inode(dentry), new_length);
849 	if (rc)
850 		return rc;
851 
852 	rc = truncate_upper(dentry, &ia, &lower_ia);
853 	if (!rc && lower_ia.ia_valid & ATTR_SIZE) {
854 		struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
855 
856 		inode_lock(d_inode(lower_dentry));
857 		rc = notify_change(&init_user_ns, lower_dentry,
858 				   &lower_ia, NULL);
859 		inode_unlock(d_inode(lower_dentry));
860 	}
861 	return rc;
862 }
863 
864 static int
865 ecryptfs_permission(struct user_namespace *mnt_userns, struct inode *inode,
866 		    int mask)
867 {
868 	return inode_permission(&init_user_ns,
869 				ecryptfs_inode_to_lower(inode), mask);
870 }
871 
872 /**
873  * ecryptfs_setattr
874  * @mnt_userns: user namespace of the target mount
875  * @dentry: dentry handle to the inode to modify
876  * @ia: Structure with flags of what to change and values
877  *
878  * Updates the metadata of an inode. If the update is to the size
879  * i.e. truncation, then ecryptfs_truncate will handle the size modification
880  * of both the ecryptfs inode and the lower inode.
881  *
882  * All other metadata changes will be passed right to the lower filesystem,
883  * and we will just update our inode to look like the lower.
884  */
885 static int ecryptfs_setattr(struct user_namespace *mnt_userns,
886 			    struct dentry *dentry, struct iattr *ia)
887 {
888 	int rc = 0;
889 	struct dentry *lower_dentry;
890 	struct iattr lower_ia;
891 	struct inode *inode;
892 	struct inode *lower_inode;
893 	struct ecryptfs_crypt_stat *crypt_stat;
894 
895 	crypt_stat = &ecryptfs_inode_to_private(d_inode(dentry))->crypt_stat;
896 	if (!(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED)) {
897 		rc = ecryptfs_init_crypt_stat(crypt_stat);
898 		if (rc)
899 			return rc;
900 	}
901 	inode = d_inode(dentry);
902 	lower_inode = ecryptfs_inode_to_lower(inode);
903 	lower_dentry = ecryptfs_dentry_to_lower(dentry);
904 	mutex_lock(&crypt_stat->cs_mutex);
905 	if (d_is_dir(dentry))
906 		crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
907 	else if (d_is_reg(dentry)
908 		 && (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
909 		     || !(crypt_stat->flags & ECRYPTFS_KEY_VALID))) {
910 		struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
911 
912 		mount_crypt_stat = &ecryptfs_superblock_to_private(
913 			dentry->d_sb)->mount_crypt_stat;
914 		rc = ecryptfs_get_lower_file(dentry, inode);
915 		if (rc) {
916 			mutex_unlock(&crypt_stat->cs_mutex);
917 			goto out;
918 		}
919 		rc = ecryptfs_read_metadata(dentry);
920 		ecryptfs_put_lower_file(inode);
921 		if (rc) {
922 			if (!(mount_crypt_stat->flags
923 			      & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
924 				rc = -EIO;
925 				printk(KERN_WARNING "Either the lower file "
926 				       "is not in a valid eCryptfs format, "
927 				       "or the key could not be retrieved. "
928 				       "Plaintext passthrough mode is not "
929 				       "enabled; returning -EIO\n");
930 				mutex_unlock(&crypt_stat->cs_mutex);
931 				goto out;
932 			}
933 			rc = 0;
934 			crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
935 					       | ECRYPTFS_ENCRYPTED);
936 		}
937 	}
938 	mutex_unlock(&crypt_stat->cs_mutex);
939 
940 	rc = setattr_prepare(&init_user_ns, dentry, ia);
941 	if (rc)
942 		goto out;
943 	if (ia->ia_valid & ATTR_SIZE) {
944 		rc = ecryptfs_inode_newsize_ok(inode, ia->ia_size);
945 		if (rc)
946 			goto out;
947 	}
948 
949 	memcpy(&lower_ia, ia, sizeof(lower_ia));
950 	if (ia->ia_valid & ATTR_FILE)
951 		lower_ia.ia_file = ecryptfs_file_to_lower(ia->ia_file);
952 	if (ia->ia_valid & ATTR_SIZE) {
953 		rc = truncate_upper(dentry, ia, &lower_ia);
954 		if (rc < 0)
955 			goto out;
956 	}
957 
958 	/*
959 	 * mode change is for clearing setuid/setgid bits. Allow lower fs
960 	 * to interpret this in its own way.
961 	 */
962 	if (lower_ia.ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
963 		lower_ia.ia_valid &= ~ATTR_MODE;
964 
965 	inode_lock(d_inode(lower_dentry));
966 	rc = notify_change(&init_user_ns, lower_dentry, &lower_ia, NULL);
967 	inode_unlock(d_inode(lower_dentry));
968 out:
969 	fsstack_copy_attr_all(inode, lower_inode);
970 	return rc;
971 }
972 
973 static int ecryptfs_getattr_link(struct user_namespace *mnt_userns,
974 				 const struct path *path, struct kstat *stat,
975 				 u32 request_mask, unsigned int flags)
976 {
977 	struct dentry *dentry = path->dentry;
978 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
979 	int rc = 0;
980 
981 	mount_crypt_stat = &ecryptfs_superblock_to_private(
982 						dentry->d_sb)->mount_crypt_stat;
983 	generic_fillattr(&init_user_ns, d_inode(dentry), stat);
984 	if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
985 		char *target;
986 		size_t targetsiz;
987 
988 		target = ecryptfs_readlink_lower(dentry, &targetsiz);
989 		if (!IS_ERR(target)) {
990 			kfree(target);
991 			stat->size = targetsiz;
992 		} else {
993 			rc = PTR_ERR(target);
994 		}
995 	}
996 	return rc;
997 }
998 
999 static int ecryptfs_getattr(struct user_namespace *mnt_userns,
1000 			    const struct path *path, struct kstat *stat,
1001 			    u32 request_mask, unsigned int flags)
1002 {
1003 	struct dentry *dentry = path->dentry;
1004 	struct kstat lower_stat;
1005 	int rc;
1006 
1007 	rc = vfs_getattr(ecryptfs_dentry_to_lower_path(dentry), &lower_stat,
1008 			 request_mask, flags);
1009 	if (!rc) {
1010 		fsstack_copy_attr_all(d_inode(dentry),
1011 				      ecryptfs_inode_to_lower(d_inode(dentry)));
1012 		generic_fillattr(&init_user_ns, d_inode(dentry), stat);
1013 		stat->blocks = lower_stat.blocks;
1014 	}
1015 	return rc;
1016 }
1017 
1018 int
1019 ecryptfs_setxattr(struct dentry *dentry, struct inode *inode,
1020 		  const char *name, const void *value,
1021 		  size_t size, int flags)
1022 {
1023 	int rc;
1024 	struct dentry *lower_dentry;
1025 	struct inode *lower_inode;
1026 
1027 	lower_dentry = ecryptfs_dentry_to_lower(dentry);
1028 	lower_inode = d_inode(lower_dentry);
1029 	if (!(lower_inode->i_opflags & IOP_XATTR)) {
1030 		rc = -EOPNOTSUPP;
1031 		goto out;
1032 	}
1033 	inode_lock(lower_inode);
1034 	rc = __vfs_setxattr_locked(&init_user_ns, lower_dentry, name, value, size, flags, NULL);
1035 	inode_unlock(lower_inode);
1036 	if (!rc && inode)
1037 		fsstack_copy_attr_all(inode, lower_inode);
1038 out:
1039 	return rc;
1040 }
1041 
1042 ssize_t
1043 ecryptfs_getxattr_lower(struct dentry *lower_dentry, struct inode *lower_inode,
1044 			const char *name, void *value, size_t size)
1045 {
1046 	int rc;
1047 
1048 	if (!(lower_inode->i_opflags & IOP_XATTR)) {
1049 		rc = -EOPNOTSUPP;
1050 		goto out;
1051 	}
1052 	inode_lock(lower_inode);
1053 	rc = __vfs_getxattr(lower_dentry, lower_inode, name, value, size);
1054 	inode_unlock(lower_inode);
1055 out:
1056 	return rc;
1057 }
1058 
1059 static ssize_t
1060 ecryptfs_getxattr(struct dentry *dentry, struct inode *inode,
1061 		  const char *name, void *value, size_t size)
1062 {
1063 	return ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
1064 				       ecryptfs_inode_to_lower(inode),
1065 				       name, value, size);
1066 }
1067 
1068 static ssize_t
1069 ecryptfs_listxattr(struct dentry *dentry, char *list, size_t size)
1070 {
1071 	int rc = 0;
1072 	struct dentry *lower_dentry;
1073 
1074 	lower_dentry = ecryptfs_dentry_to_lower(dentry);
1075 	if (!d_inode(lower_dentry)->i_op->listxattr) {
1076 		rc = -EOPNOTSUPP;
1077 		goto out;
1078 	}
1079 	inode_lock(d_inode(lower_dentry));
1080 	rc = d_inode(lower_dentry)->i_op->listxattr(lower_dentry, list, size);
1081 	inode_unlock(d_inode(lower_dentry));
1082 out:
1083 	return rc;
1084 }
1085 
1086 static int ecryptfs_removexattr(struct dentry *dentry, struct inode *inode,
1087 				const char *name)
1088 {
1089 	int rc;
1090 	struct dentry *lower_dentry;
1091 	struct inode *lower_inode;
1092 
1093 	lower_dentry = ecryptfs_dentry_to_lower(dentry);
1094 	lower_inode = ecryptfs_inode_to_lower(inode);
1095 	if (!(lower_inode->i_opflags & IOP_XATTR)) {
1096 		rc = -EOPNOTSUPP;
1097 		goto out;
1098 	}
1099 	inode_lock(lower_inode);
1100 	rc = __vfs_removexattr(&init_user_ns, lower_dentry, name);
1101 	inode_unlock(lower_inode);
1102 out:
1103 	return rc;
1104 }
1105 
1106 static int ecryptfs_fileattr_get(struct dentry *dentry, struct fileattr *fa)
1107 {
1108 	return vfs_fileattr_get(ecryptfs_dentry_to_lower(dentry), fa);
1109 }
1110 
1111 static int ecryptfs_fileattr_set(struct user_namespace *mnt_userns,
1112 				 struct dentry *dentry, struct fileattr *fa)
1113 {
1114 	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
1115 	int rc;
1116 
1117 	rc = vfs_fileattr_set(&init_user_ns, lower_dentry, fa);
1118 	fsstack_copy_attr_all(d_inode(dentry), d_inode(lower_dentry));
1119 
1120 	return rc;
1121 }
1122 
1123 const struct inode_operations ecryptfs_symlink_iops = {
1124 	.get_link = ecryptfs_get_link,
1125 	.permission = ecryptfs_permission,
1126 	.setattr = ecryptfs_setattr,
1127 	.getattr = ecryptfs_getattr_link,
1128 	.listxattr = ecryptfs_listxattr,
1129 };
1130 
1131 const struct inode_operations ecryptfs_dir_iops = {
1132 	.create = ecryptfs_create,
1133 	.lookup = ecryptfs_lookup,
1134 	.link = ecryptfs_link,
1135 	.unlink = ecryptfs_unlink,
1136 	.symlink = ecryptfs_symlink,
1137 	.mkdir = ecryptfs_mkdir,
1138 	.rmdir = ecryptfs_rmdir,
1139 	.mknod = ecryptfs_mknod,
1140 	.rename = ecryptfs_rename,
1141 	.permission = ecryptfs_permission,
1142 	.setattr = ecryptfs_setattr,
1143 	.listxattr = ecryptfs_listxattr,
1144 	.fileattr_get = ecryptfs_fileattr_get,
1145 	.fileattr_set = ecryptfs_fileattr_set,
1146 };
1147 
1148 const struct inode_operations ecryptfs_main_iops = {
1149 	.permission = ecryptfs_permission,
1150 	.setattr = ecryptfs_setattr,
1151 	.getattr = ecryptfs_getattr,
1152 	.listxattr = ecryptfs_listxattr,
1153 	.fileattr_get = ecryptfs_fileattr_get,
1154 	.fileattr_set = ecryptfs_fileattr_set,
1155 };
1156 
1157 static int ecryptfs_xattr_get(const struct xattr_handler *handler,
1158 			      struct dentry *dentry, struct inode *inode,
1159 			      const char *name, void *buffer, size_t size)
1160 {
1161 	return ecryptfs_getxattr(dentry, inode, name, buffer, size);
1162 }
1163 
1164 static int ecryptfs_xattr_set(const struct xattr_handler *handler,
1165 			      struct user_namespace *mnt_userns,
1166 			      struct dentry *dentry, struct inode *inode,
1167 			      const char *name, const void *value, size_t size,
1168 			      int flags)
1169 {
1170 	if (value)
1171 		return ecryptfs_setxattr(dentry, inode, name, value, size, flags);
1172 	else {
1173 		BUG_ON(flags != XATTR_REPLACE);
1174 		return ecryptfs_removexattr(dentry, inode, name);
1175 	}
1176 }
1177 
1178 static const struct xattr_handler ecryptfs_xattr_handler = {
1179 	.prefix = "",  /* match anything */
1180 	.get = ecryptfs_xattr_get,
1181 	.set = ecryptfs_xattr_set,
1182 };
1183 
1184 const struct xattr_handler *ecryptfs_xattr_handlers[] = {
1185 	&ecryptfs_xattr_handler,
1186 	NULL
1187 };
1188