xref: /openbmc/linux/fs/ecryptfs/inode.c (revision 545e4006)
1 /**
2  * eCryptfs: Linux filesystem encryption layer
3  *
4  * Copyright (C) 1997-2004 Erez Zadok
5  * Copyright (C) 2001-2004 Stony Brook University
6  * Copyright (C) 2004-2007 International Business Machines Corp.
7  *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
8  *              Michael C. Thompsion <mcthomps@us.ibm.com>
9  *
10  * This program is free software; you can redistribute it and/or
11  * modify it under the terms of the GNU General Public License as
12  * published by the Free Software Foundation; either version 2 of the
13  * License, or (at your option) any later version.
14  *
15  * This program is distributed in the hope that it will be useful, but
16  * WITHOUT ANY WARRANTY; without even the implied warranty of
17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
18  * General Public License for more details.
19  *
20  * You should have received a copy of the GNU General Public License
21  * along with this program; if not, write to the Free Software
22  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
23  * 02111-1307, USA.
24  */
25 
26 #include <linux/file.h>
27 #include <linux/vmalloc.h>
28 #include <linux/pagemap.h>
29 #include <linux/dcache.h>
30 #include <linux/namei.h>
31 #include <linux/mount.h>
32 #include <linux/crypto.h>
33 #include <linux/fs_stack.h>
34 #include <asm/unaligned.h>
35 #include "ecryptfs_kernel.h"
36 
37 static struct dentry *lock_parent(struct dentry *dentry)
38 {
39 	struct dentry *dir;
40 
41 	dir = dget_parent(dentry);
42 	mutex_lock_nested(&(dir->d_inode->i_mutex), I_MUTEX_PARENT);
43 	return dir;
44 }
45 
46 static void unlock_dir(struct dentry *dir)
47 {
48 	mutex_unlock(&dir->d_inode->i_mutex);
49 	dput(dir);
50 }
51 
52 /**
53  * ecryptfs_create_underlying_file
54  * @lower_dir_inode: inode of the parent in the lower fs of the new file
55  * @lower_dentry: New file's dentry in the lower fs
56  * @ecryptfs_dentry: New file's dentry in ecryptfs
57  * @mode: The mode of the new file
58  * @nd: nameidata of ecryptfs' parent's dentry & vfsmount
59  *
60  * Creates the file in the lower file system.
61  *
62  * Returns zero on success; non-zero on error condition
63  */
64 static int
65 ecryptfs_create_underlying_file(struct inode *lower_dir_inode,
66 				struct dentry *dentry, int mode,
67 				struct nameidata *nd)
68 {
69 	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
70 	struct vfsmount *lower_mnt = ecryptfs_dentry_to_lower_mnt(dentry);
71 	struct dentry *dentry_save;
72 	struct vfsmount *vfsmount_save;
73 	int rc;
74 
75 	dentry_save = nd->path.dentry;
76 	vfsmount_save = nd->path.mnt;
77 	nd->path.dentry = lower_dentry;
78 	nd->path.mnt = lower_mnt;
79 	rc = vfs_create(lower_dir_inode, lower_dentry, mode, nd);
80 	nd->path.dentry = dentry_save;
81 	nd->path.mnt = vfsmount_save;
82 	return rc;
83 }
84 
85 /**
86  * ecryptfs_do_create
87  * @directory_inode: inode of the new file's dentry's parent in ecryptfs
88  * @ecryptfs_dentry: New file's dentry in ecryptfs
89  * @mode: The mode of the new file
90  * @nd: nameidata of ecryptfs' parent's dentry & vfsmount
91  *
92  * Creates the underlying file and the eCryptfs inode which will link to
93  * it. It will also update the eCryptfs directory inode to mimic the
94  * stat of the lower directory inode.
95  *
96  * Returns zero on success; non-zero on error condition
97  */
98 static int
99 ecryptfs_do_create(struct inode *directory_inode,
100 		   struct dentry *ecryptfs_dentry, int mode,
101 		   struct nameidata *nd)
102 {
103 	int rc;
104 	struct dentry *lower_dentry;
105 	struct dentry *lower_dir_dentry;
106 
107 	lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
108 	lower_dir_dentry = lock_parent(lower_dentry);
109 	if (IS_ERR(lower_dir_dentry)) {
110 		ecryptfs_printk(KERN_ERR, "Error locking directory of "
111 				"dentry\n");
112 		rc = PTR_ERR(lower_dir_dentry);
113 		goto out;
114 	}
115 	rc = ecryptfs_create_underlying_file(lower_dir_dentry->d_inode,
116 					     ecryptfs_dentry, mode, nd);
117 	if (rc) {
118 		printk(KERN_ERR "%s: Failure to create dentry in lower fs; "
119 		       "rc = [%d]\n", __func__, rc);
120 		goto out_lock;
121 	}
122 	rc = ecryptfs_interpose(lower_dentry, ecryptfs_dentry,
123 				directory_inode->i_sb, 0);
124 	if (rc) {
125 		ecryptfs_printk(KERN_ERR, "Failure in ecryptfs_interpose\n");
126 		goto out_lock;
127 	}
128 	fsstack_copy_attr_times(directory_inode, lower_dir_dentry->d_inode);
129 	fsstack_copy_inode_size(directory_inode, lower_dir_dentry->d_inode);
130 out_lock:
131 	unlock_dir(lower_dir_dentry);
132 out:
133 	return rc;
134 }
135 
136 /**
137  * grow_file
138  * @ecryptfs_dentry: the eCryptfs dentry
139  *
140  * This is the code which will grow the file to its correct size.
141  */
142 static int grow_file(struct dentry *ecryptfs_dentry)
143 {
144 	struct inode *ecryptfs_inode = ecryptfs_dentry->d_inode;
145 	struct file fake_file;
146 	struct ecryptfs_file_info tmp_file_info;
147 	char zero_virt[] = { 0x00 };
148 	int rc = 0;
149 
150 	memset(&fake_file, 0, sizeof(fake_file));
151 	fake_file.f_path.dentry = ecryptfs_dentry;
152 	memset(&tmp_file_info, 0, sizeof(tmp_file_info));
153 	ecryptfs_set_file_private(&fake_file, &tmp_file_info);
154 	ecryptfs_set_file_lower(
155 		&fake_file,
156 		ecryptfs_inode_to_private(ecryptfs_inode)->lower_file);
157 	rc = ecryptfs_write(&fake_file, zero_virt, 0, 1);
158 	i_size_write(ecryptfs_inode, 0);
159 	rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode);
160 	ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat.flags |=
161 		ECRYPTFS_NEW_FILE;
162 	return rc;
163 }
164 
165 /**
166  * ecryptfs_initialize_file
167  *
168  * Cause the file to be changed from a basic empty file to an ecryptfs
169  * file with a header and first data page.
170  *
171  * Returns zero on success
172  */
173 static int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry)
174 {
175 	struct ecryptfs_crypt_stat *crypt_stat =
176 		&ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
177 	int rc = 0;
178 
179 	if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
180 		ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
181 		crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
182 		goto out;
183 	}
184 	crypt_stat->flags |= ECRYPTFS_NEW_FILE;
185 	ecryptfs_printk(KERN_DEBUG, "Initializing crypto context\n");
186 	rc = ecryptfs_new_file_context(ecryptfs_dentry);
187 	if (rc) {
188 		ecryptfs_printk(KERN_ERR, "Error creating new file "
189 				"context; rc = [%d]\n", rc);
190 		goto out;
191 	}
192 	if (!ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->lower_file) {
193 		rc = ecryptfs_init_persistent_file(ecryptfs_dentry);
194 		if (rc) {
195 			printk(KERN_ERR "%s: Error attempting to initialize "
196 			       "the persistent file for the dentry with name "
197 			       "[%s]; rc = [%d]\n", __func__,
198 			       ecryptfs_dentry->d_name.name, rc);
199 			goto out;
200 		}
201 	}
202 	rc = ecryptfs_write_metadata(ecryptfs_dentry);
203 	if (rc) {
204 		printk(KERN_ERR "Error writing headers; rc = [%d]\n", rc);
205 		goto out;
206 	}
207 	rc = grow_file(ecryptfs_dentry);
208 	if (rc)
209 		printk(KERN_ERR "Error growing file; rc = [%d]\n", rc);
210 out:
211 	return rc;
212 }
213 
214 /**
215  * ecryptfs_create
216  * @dir: The inode of the directory in which to create the file.
217  * @dentry: The eCryptfs dentry
218  * @mode: The mode of the new file.
219  * @nd: nameidata
220  *
221  * Creates a new file.
222  *
223  * Returns zero on success; non-zero on error condition
224  */
225 static int
226 ecryptfs_create(struct inode *directory_inode, struct dentry *ecryptfs_dentry,
227 		int mode, struct nameidata *nd)
228 {
229 	int rc;
230 
231 	/* ecryptfs_do_create() calls ecryptfs_interpose(), which opens
232 	 * the crypt_stat->lower_file (persistent file) */
233 	rc = ecryptfs_do_create(directory_inode, ecryptfs_dentry, mode, nd);
234 	if (unlikely(rc)) {
235 		ecryptfs_printk(KERN_WARNING, "Failed to create file in"
236 				"lower filesystem\n");
237 		goto out;
238 	}
239 	/* At this point, a file exists on "disk"; we need to make sure
240 	 * that this on disk file is prepared to be an ecryptfs file */
241 	rc = ecryptfs_initialize_file(ecryptfs_dentry);
242 out:
243 	return rc;
244 }
245 
246 /**
247  * ecryptfs_lookup
248  * @dir: inode
249  * @dentry: The dentry
250  * @nd: nameidata, may be NULL
251  *
252  * Find a file on disk. If the file does not exist, then we'll add it to the
253  * dentry cache and continue on to read it from the disk.
254  */
255 static struct dentry *ecryptfs_lookup(struct inode *dir, struct dentry *dentry,
256 				      struct nameidata *nd)
257 {
258 	int rc = 0;
259 	struct dentry *lower_dir_dentry;
260 	struct dentry *lower_dentry;
261 	struct vfsmount *lower_mnt;
262 	char *encoded_name;
263 	int encoded_namelen;
264 	struct ecryptfs_crypt_stat *crypt_stat = NULL;
265 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
266 	char *page_virt = NULL;
267 	struct inode *lower_inode;
268 	u64 file_size;
269 
270 	lower_dir_dentry = ecryptfs_dentry_to_lower(dentry->d_parent);
271 	dentry->d_op = &ecryptfs_dops;
272 	if ((dentry->d_name.len == 1 && !strcmp(dentry->d_name.name, "."))
273 	    || (dentry->d_name.len == 2
274 		&& !strcmp(dentry->d_name.name, ".."))) {
275 		d_drop(dentry);
276 		goto out;
277 	}
278 	encoded_namelen = ecryptfs_encode_filename(crypt_stat,
279 						   dentry->d_name.name,
280 						   dentry->d_name.len,
281 						   &encoded_name);
282 	if (encoded_namelen < 0) {
283 		rc = encoded_namelen;
284 		d_drop(dentry);
285 		goto out;
286 	}
287 	ecryptfs_printk(KERN_DEBUG, "encoded_name = [%s]; encoded_namelen "
288 			"= [%d]\n", encoded_name, encoded_namelen);
289 	lower_dentry = lookup_one_len(encoded_name, lower_dir_dentry,
290 				      encoded_namelen - 1);
291 	kfree(encoded_name);
292 	if (IS_ERR(lower_dentry)) {
293 		ecryptfs_printk(KERN_ERR, "ERR from lower_dentry\n");
294 		rc = PTR_ERR(lower_dentry);
295 		d_drop(dentry);
296 		goto out;
297 	}
298 	lower_mnt = mntget(ecryptfs_dentry_to_lower_mnt(dentry->d_parent));
299 	ecryptfs_printk(KERN_DEBUG, "lower_dentry = [%p]; lower_dentry->"
300        		"d_name.name = [%s]\n", lower_dentry,
301 		lower_dentry->d_name.name);
302 	lower_inode = lower_dentry->d_inode;
303 	fsstack_copy_attr_atime(dir, lower_dir_dentry->d_inode);
304 	BUG_ON(!atomic_read(&lower_dentry->d_count));
305 	ecryptfs_set_dentry_private(dentry,
306 				    kmem_cache_alloc(ecryptfs_dentry_info_cache,
307 						     GFP_KERNEL));
308 	if (!ecryptfs_dentry_to_private(dentry)) {
309 		rc = -ENOMEM;
310 		ecryptfs_printk(KERN_ERR, "Out of memory whilst attempting "
311 				"to allocate ecryptfs_dentry_info struct\n");
312 		goto out_dput;
313 	}
314 	ecryptfs_set_dentry_lower(dentry, lower_dentry);
315 	ecryptfs_set_dentry_lower_mnt(dentry, lower_mnt);
316 	if (!lower_dentry->d_inode) {
317 		/* We want to add because we couldn't find in lower */
318 		d_add(dentry, NULL);
319 		goto out;
320 	}
321 	rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb,
322 				ECRYPTFS_INTERPOSE_FLAG_D_ADD);
323 	if (rc) {
324 		ecryptfs_printk(KERN_ERR, "Error interposing\n");
325 		goto out;
326 	}
327 	if (S_ISDIR(lower_inode->i_mode)) {
328 		ecryptfs_printk(KERN_DEBUG, "Is a directory; returning\n");
329 		goto out;
330 	}
331 	if (S_ISLNK(lower_inode->i_mode)) {
332 		ecryptfs_printk(KERN_DEBUG, "Is a symlink; returning\n");
333 		goto out;
334 	}
335 	if (special_file(lower_inode->i_mode)) {
336 		ecryptfs_printk(KERN_DEBUG, "Is a special file; returning\n");
337 		goto out;
338 	}
339 	if (!nd) {
340 		ecryptfs_printk(KERN_DEBUG, "We have a NULL nd, just leave"
341 				"as we *think* we are about to unlink\n");
342 		goto out;
343 	}
344 	/* Released in this function */
345 	page_virt = kmem_cache_zalloc(ecryptfs_header_cache_2,
346 				      GFP_USER);
347 	if (!page_virt) {
348 		rc = -ENOMEM;
349 		ecryptfs_printk(KERN_ERR,
350 				"Cannot ecryptfs_kmalloc a page\n");
351 		goto out;
352 	}
353 	crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
354 	if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED))
355 		ecryptfs_set_default_sizes(crypt_stat);
356 	if (!ecryptfs_inode_to_private(dentry->d_inode)->lower_file) {
357 		rc = ecryptfs_init_persistent_file(dentry);
358 		if (rc) {
359 			printk(KERN_ERR "%s: Error attempting to initialize "
360 			       "the persistent file for the dentry with name "
361 			       "[%s]; rc = [%d]\n", __func__,
362 			       dentry->d_name.name, rc);
363 			goto out;
364 		}
365 	}
366 	rc = ecryptfs_read_and_validate_header_region(page_virt,
367 						      dentry->d_inode);
368 	if (rc) {
369 		rc = ecryptfs_read_and_validate_xattr_region(page_virt, dentry);
370 		if (rc) {
371 			printk(KERN_DEBUG "Valid metadata not found in header "
372 			       "region or xattr region; treating file as "
373 			       "unencrypted\n");
374 			rc = 0;
375 			kmem_cache_free(ecryptfs_header_cache_2, page_virt);
376 			goto out;
377 		}
378 		crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
379 	}
380 	mount_crypt_stat = &ecryptfs_superblock_to_private(
381 		dentry->d_sb)->mount_crypt_stat;
382 	if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
383 		if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
384 			file_size = (crypt_stat->num_header_bytes_at_front
385 				     + i_size_read(lower_dentry->d_inode));
386 		else
387 			file_size = i_size_read(lower_dentry->d_inode);
388 	} else {
389 		file_size = get_unaligned_be64(page_virt);
390 	}
391 	i_size_write(dentry->d_inode, (loff_t)file_size);
392 	kmem_cache_free(ecryptfs_header_cache_2, page_virt);
393 	goto out;
394 
395 out_dput:
396 	dput(lower_dentry);
397 	d_drop(dentry);
398 out:
399 	return ERR_PTR(rc);
400 }
401 
402 static int ecryptfs_link(struct dentry *old_dentry, struct inode *dir,
403 			 struct dentry *new_dentry)
404 {
405 	struct dentry *lower_old_dentry;
406 	struct dentry *lower_new_dentry;
407 	struct dentry *lower_dir_dentry;
408 	u64 file_size_save;
409 	int rc;
410 
411 	file_size_save = i_size_read(old_dentry->d_inode);
412 	lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
413 	lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
414 	dget(lower_old_dentry);
415 	dget(lower_new_dentry);
416 	lower_dir_dentry = lock_parent(lower_new_dentry);
417 	rc = vfs_link(lower_old_dentry, lower_dir_dentry->d_inode,
418 		      lower_new_dentry);
419 	if (rc || !lower_new_dentry->d_inode)
420 		goto out_lock;
421 	rc = ecryptfs_interpose(lower_new_dentry, new_dentry, dir->i_sb, 0);
422 	if (rc)
423 		goto out_lock;
424 	fsstack_copy_attr_times(dir, lower_new_dentry->d_inode);
425 	fsstack_copy_inode_size(dir, lower_new_dentry->d_inode);
426 	old_dentry->d_inode->i_nlink =
427 		ecryptfs_inode_to_lower(old_dentry->d_inode)->i_nlink;
428 	i_size_write(new_dentry->d_inode, file_size_save);
429 out_lock:
430 	unlock_dir(lower_dir_dentry);
431 	dput(lower_new_dentry);
432 	dput(lower_old_dentry);
433 	d_drop(lower_old_dentry);
434 	d_drop(new_dentry);
435 	d_drop(old_dentry);
436 	return rc;
437 }
438 
439 static int ecryptfs_unlink(struct inode *dir, struct dentry *dentry)
440 {
441 	int rc = 0;
442 	struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
443 	struct inode *lower_dir_inode = ecryptfs_inode_to_lower(dir);
444 	struct dentry *lower_dir_dentry;
445 
446 	lower_dir_dentry = lock_parent(lower_dentry);
447 	rc = vfs_unlink(lower_dir_inode, lower_dentry);
448 	if (rc) {
449 		printk(KERN_ERR "Error in vfs_unlink; rc = [%d]\n", rc);
450 		goto out_unlock;
451 	}
452 	fsstack_copy_attr_times(dir, lower_dir_inode);
453 	dentry->d_inode->i_nlink =
454 		ecryptfs_inode_to_lower(dentry->d_inode)->i_nlink;
455 	dentry->d_inode->i_ctime = dir->i_ctime;
456 	d_drop(dentry);
457 out_unlock:
458 	unlock_dir(lower_dir_dentry);
459 	return rc;
460 }
461 
462 static int ecryptfs_symlink(struct inode *dir, struct dentry *dentry,
463 			    const char *symname)
464 {
465 	int rc;
466 	struct dentry *lower_dentry;
467 	struct dentry *lower_dir_dentry;
468 	umode_t mode;
469 	char *encoded_symname;
470 	int encoded_symlen;
471 	struct ecryptfs_crypt_stat *crypt_stat = NULL;
472 
473 	lower_dentry = ecryptfs_dentry_to_lower(dentry);
474 	dget(lower_dentry);
475 	lower_dir_dentry = lock_parent(lower_dentry);
476 	mode = S_IALLUGO;
477 	encoded_symlen = ecryptfs_encode_filename(crypt_stat, symname,
478 						  strlen(symname),
479 						  &encoded_symname);
480 	if (encoded_symlen < 0) {
481 		rc = encoded_symlen;
482 		goto out_lock;
483 	}
484 	rc = vfs_symlink(lower_dir_dentry->d_inode, lower_dentry,
485 			 encoded_symname, mode);
486 	kfree(encoded_symname);
487 	if (rc || !lower_dentry->d_inode)
488 		goto out_lock;
489 	rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
490 	if (rc)
491 		goto out_lock;
492 	fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
493 	fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
494 out_lock:
495 	unlock_dir(lower_dir_dentry);
496 	dput(lower_dentry);
497 	if (!dentry->d_inode)
498 		d_drop(dentry);
499 	return rc;
500 }
501 
502 static int ecryptfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
503 {
504 	int rc;
505 	struct dentry *lower_dentry;
506 	struct dentry *lower_dir_dentry;
507 
508 	lower_dentry = ecryptfs_dentry_to_lower(dentry);
509 	lower_dir_dentry = lock_parent(lower_dentry);
510 	rc = vfs_mkdir(lower_dir_dentry->d_inode, lower_dentry, mode);
511 	if (rc || !lower_dentry->d_inode)
512 		goto out;
513 	rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
514 	if (rc)
515 		goto out;
516 	fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
517 	fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
518 	dir->i_nlink = lower_dir_dentry->d_inode->i_nlink;
519 out:
520 	unlock_dir(lower_dir_dentry);
521 	if (!dentry->d_inode)
522 		d_drop(dentry);
523 	return rc;
524 }
525 
526 static int ecryptfs_rmdir(struct inode *dir, struct dentry *dentry)
527 {
528 	struct dentry *lower_dentry;
529 	struct dentry *lower_dir_dentry;
530 	int rc;
531 
532 	lower_dentry = ecryptfs_dentry_to_lower(dentry);
533 	dget(dentry);
534 	lower_dir_dentry = lock_parent(lower_dentry);
535 	dget(lower_dentry);
536 	rc = vfs_rmdir(lower_dir_dentry->d_inode, lower_dentry);
537 	dput(lower_dentry);
538 	if (!rc)
539 		d_delete(lower_dentry);
540 	fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
541 	dir->i_nlink = lower_dir_dentry->d_inode->i_nlink;
542 	unlock_dir(lower_dir_dentry);
543 	if (!rc)
544 		d_drop(dentry);
545 	dput(dentry);
546 	return rc;
547 }
548 
549 static int
550 ecryptfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
551 {
552 	int rc;
553 	struct dentry *lower_dentry;
554 	struct dentry *lower_dir_dentry;
555 
556 	lower_dentry = ecryptfs_dentry_to_lower(dentry);
557 	lower_dir_dentry = lock_parent(lower_dentry);
558 	rc = vfs_mknod(lower_dir_dentry->d_inode, lower_dentry, mode, dev);
559 	if (rc || !lower_dentry->d_inode)
560 		goto out;
561 	rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
562 	if (rc)
563 		goto out;
564 	fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
565 	fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
566 out:
567 	unlock_dir(lower_dir_dentry);
568 	if (!dentry->d_inode)
569 		d_drop(dentry);
570 	return rc;
571 }
572 
573 static int
574 ecryptfs_rename(struct inode *old_dir, struct dentry *old_dentry,
575 		struct inode *new_dir, struct dentry *new_dentry)
576 {
577 	int rc;
578 	struct dentry *lower_old_dentry;
579 	struct dentry *lower_new_dentry;
580 	struct dentry *lower_old_dir_dentry;
581 	struct dentry *lower_new_dir_dentry;
582 
583 	lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
584 	lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
585 	dget(lower_old_dentry);
586 	dget(lower_new_dentry);
587 	lower_old_dir_dentry = dget_parent(lower_old_dentry);
588 	lower_new_dir_dentry = dget_parent(lower_new_dentry);
589 	lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
590 	rc = vfs_rename(lower_old_dir_dentry->d_inode, lower_old_dentry,
591 			lower_new_dir_dentry->d_inode, lower_new_dentry);
592 	if (rc)
593 		goto out_lock;
594 	fsstack_copy_attr_all(new_dir, lower_new_dir_dentry->d_inode, NULL);
595 	if (new_dir != old_dir)
596 		fsstack_copy_attr_all(old_dir, lower_old_dir_dentry->d_inode, NULL);
597 out_lock:
598 	unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
599 	dput(lower_new_dentry->d_parent);
600 	dput(lower_old_dentry->d_parent);
601 	dput(lower_new_dentry);
602 	dput(lower_old_dentry);
603 	return rc;
604 }
605 
606 static int
607 ecryptfs_readlink(struct dentry *dentry, char __user * buf, int bufsiz)
608 {
609 	int rc;
610 	struct dentry *lower_dentry;
611 	char *decoded_name;
612 	char *lower_buf;
613 	mm_segment_t old_fs;
614 	struct ecryptfs_crypt_stat *crypt_stat;
615 
616 	lower_dentry = ecryptfs_dentry_to_lower(dentry);
617 	if (!lower_dentry->d_inode->i_op ||
618 	    !lower_dentry->d_inode->i_op->readlink) {
619 		rc = -EINVAL;
620 		goto out;
621 	}
622 	/* Released in this function */
623 	lower_buf = kmalloc(bufsiz, GFP_KERNEL);
624 	if (lower_buf == NULL) {
625 		ecryptfs_printk(KERN_ERR, "Out of memory\n");
626 		rc = -ENOMEM;
627 		goto out;
628 	}
629 	old_fs = get_fs();
630 	set_fs(get_ds());
631 	ecryptfs_printk(KERN_DEBUG, "Calling readlink w/ "
632 			"lower_dentry->d_name.name = [%s]\n",
633 			lower_dentry->d_name.name);
634 	rc = lower_dentry->d_inode->i_op->readlink(lower_dentry,
635 						   (char __user *)lower_buf,
636 						   bufsiz);
637 	set_fs(old_fs);
638 	if (rc >= 0) {
639 		crypt_stat = NULL;
640 		rc = ecryptfs_decode_filename(crypt_stat, lower_buf, rc,
641 					      &decoded_name);
642 		if (rc == -ENOMEM)
643 			goto out_free_lower_buf;
644 		if (rc > 0) {
645 			ecryptfs_printk(KERN_DEBUG, "Copying [%d] bytes "
646 					"to userspace: [%*s]\n", rc,
647 					decoded_name);
648 			if (copy_to_user(buf, decoded_name, rc))
649 				rc = -EFAULT;
650 		}
651 		kfree(decoded_name);
652 		fsstack_copy_attr_atime(dentry->d_inode,
653 					lower_dentry->d_inode);
654 	}
655 out_free_lower_buf:
656 	kfree(lower_buf);
657 out:
658 	return rc;
659 }
660 
661 static void *ecryptfs_follow_link(struct dentry *dentry, struct nameidata *nd)
662 {
663 	char *buf;
664 	int len = PAGE_SIZE, rc;
665 	mm_segment_t old_fs;
666 
667 	/* Released in ecryptfs_put_link(); only release here on error */
668 	buf = kmalloc(len, GFP_KERNEL);
669 	if (!buf) {
670 		rc = -ENOMEM;
671 		goto out;
672 	}
673 	old_fs = get_fs();
674 	set_fs(get_ds());
675 	ecryptfs_printk(KERN_DEBUG, "Calling readlink w/ "
676 			"dentry->d_name.name = [%s]\n", dentry->d_name.name);
677 	rc = dentry->d_inode->i_op->readlink(dentry, (char __user *)buf, len);
678 	buf[rc] = '\0';
679 	set_fs(old_fs);
680 	if (rc < 0)
681 		goto out_free;
682 	rc = 0;
683 	nd_set_link(nd, buf);
684 	goto out;
685 out_free:
686 	kfree(buf);
687 out:
688 	return ERR_PTR(rc);
689 }
690 
691 static void
692 ecryptfs_put_link(struct dentry *dentry, struct nameidata *nd, void *ptr)
693 {
694 	/* Free the char* */
695 	kfree(nd_get_link(nd));
696 }
697 
698 /**
699  * upper_size_to_lower_size
700  * @crypt_stat: Crypt_stat associated with file
701  * @upper_size: Size of the upper file
702  *
703  * Calculate the required size of the lower file based on the
704  * specified size of the upper file. This calculation is based on the
705  * number of headers in the underlying file and the extent size.
706  *
707  * Returns Calculated size of the lower file.
708  */
709 static loff_t
710 upper_size_to_lower_size(struct ecryptfs_crypt_stat *crypt_stat,
711 			 loff_t upper_size)
712 {
713 	loff_t lower_size;
714 
715 	lower_size = crypt_stat->num_header_bytes_at_front;
716 	if (upper_size != 0) {
717 		loff_t num_extents;
718 
719 		num_extents = upper_size >> crypt_stat->extent_shift;
720 		if (upper_size & ~crypt_stat->extent_mask)
721 			num_extents++;
722 		lower_size += (num_extents * crypt_stat->extent_size);
723 	}
724 	return lower_size;
725 }
726 
727 /**
728  * ecryptfs_truncate
729  * @dentry: The ecryptfs layer dentry
730  * @new_length: The length to expand the file to
731  *
732  * Function to handle truncations modifying the size of the file. Note
733  * that the file sizes are interpolated. When expanding, we are simply
734  * writing strings of 0's out. When truncating, we need to modify the
735  * underlying file size according to the page index interpolations.
736  *
737  * Returns zero on success; non-zero otherwise
738  */
739 int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
740 {
741 	int rc = 0;
742 	struct inode *inode = dentry->d_inode;
743 	struct dentry *lower_dentry;
744 	struct file fake_ecryptfs_file;
745 	struct ecryptfs_crypt_stat *crypt_stat;
746 	loff_t i_size = i_size_read(inode);
747 	loff_t lower_size_before_truncate;
748 	loff_t lower_size_after_truncate;
749 
750 	if (unlikely((new_length == i_size)))
751 		goto out;
752 	crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
753 	/* Set up a fake ecryptfs file, this is used to interface with
754 	 * the file in the underlying filesystem so that the
755 	 * truncation has an effect there as well. */
756 	memset(&fake_ecryptfs_file, 0, sizeof(fake_ecryptfs_file));
757 	fake_ecryptfs_file.f_path.dentry = dentry;
758 	/* Released at out_free: label */
759 	ecryptfs_set_file_private(&fake_ecryptfs_file,
760 				  kmem_cache_alloc(ecryptfs_file_info_cache,
761 						   GFP_KERNEL));
762 	if (unlikely(!ecryptfs_file_to_private(&fake_ecryptfs_file))) {
763 		rc = -ENOMEM;
764 		goto out;
765 	}
766 	lower_dentry = ecryptfs_dentry_to_lower(dentry);
767 	ecryptfs_set_file_lower(
768 		&fake_ecryptfs_file,
769 		ecryptfs_inode_to_private(dentry->d_inode)->lower_file);
770 	/* Switch on growing or shrinking file */
771 	if (new_length > i_size) {
772 		char zero[] = { 0x00 };
773 
774 		/* Write a single 0 at the last position of the file;
775 		 * this triggers code that will fill in 0's throughout
776 		 * the intermediate portion of the previous end of the
777 		 * file and the new and of the file */
778 		rc = ecryptfs_write(&fake_ecryptfs_file, zero,
779 				    (new_length - 1), 1);
780 	} else { /* new_length < i_size_read(inode) */
781 		/* We're chopping off all the pages down do the page
782 		 * in which new_length is located. Fill in the end of
783 		 * that page from (new_length & ~PAGE_CACHE_MASK) to
784 		 * PAGE_CACHE_SIZE with zeros. */
785 		size_t num_zeros = (PAGE_CACHE_SIZE
786 				    - (new_length & ~PAGE_CACHE_MASK));
787 
788 		if (num_zeros) {
789 			char *zeros_virt;
790 
791 			zeros_virt = kzalloc(num_zeros, GFP_KERNEL);
792 			if (!zeros_virt) {
793 				rc = -ENOMEM;
794 				goto out_free;
795 			}
796 			rc = ecryptfs_write(&fake_ecryptfs_file, zeros_virt,
797 					    new_length, num_zeros);
798 			kfree(zeros_virt);
799 			if (rc) {
800 				printk(KERN_ERR "Error attempting to zero out "
801 				       "the remainder of the end page on "
802 				       "reducing truncate; rc = [%d]\n", rc);
803 				goto out_free;
804 			}
805 		}
806 		vmtruncate(inode, new_length);
807 		rc = ecryptfs_write_inode_size_to_metadata(inode);
808 		if (rc) {
809 			printk(KERN_ERR	"Problem with "
810 			       "ecryptfs_write_inode_size_to_metadata; "
811 			       "rc = [%d]\n", rc);
812 			goto out_free;
813 		}
814 		/* We are reducing the size of the ecryptfs file, and need to
815 		 * know if we need to reduce the size of the lower file. */
816 		lower_size_before_truncate =
817 		    upper_size_to_lower_size(crypt_stat, i_size);
818 		lower_size_after_truncate =
819 		    upper_size_to_lower_size(crypt_stat, new_length);
820 		if (lower_size_after_truncate < lower_size_before_truncate)
821 			vmtruncate(lower_dentry->d_inode,
822 				   lower_size_after_truncate);
823 	}
824 out_free:
825 	if (ecryptfs_file_to_private(&fake_ecryptfs_file))
826 		kmem_cache_free(ecryptfs_file_info_cache,
827 				ecryptfs_file_to_private(&fake_ecryptfs_file));
828 out:
829 	return rc;
830 }
831 
832 static int
833 ecryptfs_permission(struct inode *inode, int mask, struct nameidata *nd)
834 {
835 	int rc;
836 
837         if (nd) {
838 		struct vfsmount *vfsmnt_save = nd->path.mnt;
839 		struct dentry *dentry_save = nd->path.dentry;
840 
841 		nd->path.mnt = ecryptfs_dentry_to_lower_mnt(nd->path.dentry);
842 		nd->path.dentry = ecryptfs_dentry_to_lower(nd->path.dentry);
843 		rc = permission(ecryptfs_inode_to_lower(inode), mask, nd);
844 		nd->path.mnt = vfsmnt_save;
845 		nd->path.dentry = dentry_save;
846         } else
847 		rc = permission(ecryptfs_inode_to_lower(inode), mask, NULL);
848         return rc;
849 }
850 
851 /**
852  * ecryptfs_setattr
853  * @dentry: dentry handle to the inode to modify
854  * @ia: Structure with flags of what to change and values
855  *
856  * Updates the metadata of an inode. If the update is to the size
857  * i.e. truncation, then ecryptfs_truncate will handle the size modification
858  * of both the ecryptfs inode and the lower inode.
859  *
860  * All other metadata changes will be passed right to the lower filesystem,
861  * and we will just update our inode to look like the lower.
862  */
863 static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
864 {
865 	int rc = 0;
866 	struct dentry *lower_dentry;
867 	struct inode *inode;
868 	struct inode *lower_inode;
869 	struct ecryptfs_crypt_stat *crypt_stat;
870 
871 	crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
872 	if (!(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED))
873 		ecryptfs_init_crypt_stat(crypt_stat);
874 	inode = dentry->d_inode;
875 	lower_inode = ecryptfs_inode_to_lower(inode);
876 	lower_dentry = ecryptfs_dentry_to_lower(dentry);
877 	mutex_lock(&crypt_stat->cs_mutex);
878 	if (S_ISDIR(dentry->d_inode->i_mode))
879 		crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
880 	else if (S_ISREG(dentry->d_inode->i_mode)
881 		 && (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
882 		     || !(crypt_stat->flags & ECRYPTFS_KEY_VALID))) {
883 		struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
884 
885 		mount_crypt_stat = &ecryptfs_superblock_to_private(
886 			dentry->d_sb)->mount_crypt_stat;
887 		rc = ecryptfs_read_metadata(dentry);
888 		if (rc) {
889 			if (!(mount_crypt_stat->flags
890 			      & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
891 				rc = -EIO;
892 				printk(KERN_WARNING "Either the lower file "
893 				       "is not in a valid eCryptfs format, "
894 				       "or the key could not be retrieved. "
895 				       "Plaintext passthrough mode is not "
896 				       "enabled; returning -EIO\n");
897 				mutex_unlock(&crypt_stat->cs_mutex);
898 				goto out;
899 			}
900 			rc = 0;
901 			crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
902 			mutex_unlock(&crypt_stat->cs_mutex);
903 			goto out;
904 		}
905 	}
906 	mutex_unlock(&crypt_stat->cs_mutex);
907 	if (ia->ia_valid & ATTR_SIZE) {
908 		ecryptfs_printk(KERN_DEBUG,
909 				"ia->ia_valid = [0x%x] ATTR_SIZE" " = [0x%x]\n",
910 				ia->ia_valid, ATTR_SIZE);
911 		rc = ecryptfs_truncate(dentry, ia->ia_size);
912 		/* ecryptfs_truncate handles resizing of the lower file */
913 		ia->ia_valid &= ~ATTR_SIZE;
914 		ecryptfs_printk(KERN_DEBUG, "ia->ia_valid = [%x]\n",
915 				ia->ia_valid);
916 		if (rc < 0)
917 			goto out;
918 	}
919 
920 	/*
921 	 * mode change is for clearing setuid/setgid bits. Allow lower fs
922 	 * to interpret this in its own way.
923 	 */
924 	if (ia->ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
925 		ia->ia_valid &= ~ATTR_MODE;
926 
927 	mutex_lock(&lower_dentry->d_inode->i_mutex);
928 	rc = notify_change(lower_dentry, ia);
929 	mutex_unlock(&lower_dentry->d_inode->i_mutex);
930 out:
931 	fsstack_copy_attr_all(inode, lower_inode, NULL);
932 	return rc;
933 }
934 
935 int
936 ecryptfs_setxattr(struct dentry *dentry, const char *name, const void *value,
937 		  size_t size, int flags)
938 {
939 	int rc = 0;
940 	struct dentry *lower_dentry;
941 
942 	lower_dentry = ecryptfs_dentry_to_lower(dentry);
943 	if (!lower_dentry->d_inode->i_op->setxattr) {
944 		rc = -ENOSYS;
945 		goto out;
946 	}
947 	mutex_lock(&lower_dentry->d_inode->i_mutex);
948 	rc = lower_dentry->d_inode->i_op->setxattr(lower_dentry, name, value,
949 						   size, flags);
950 	mutex_unlock(&lower_dentry->d_inode->i_mutex);
951 out:
952 	return rc;
953 }
954 
955 ssize_t
956 ecryptfs_getxattr_lower(struct dentry *lower_dentry, const char *name,
957 			void *value, size_t size)
958 {
959 	int rc = 0;
960 
961 	if (!lower_dentry->d_inode->i_op->getxattr) {
962 		rc = -ENOSYS;
963 		goto out;
964 	}
965 	mutex_lock(&lower_dentry->d_inode->i_mutex);
966 	rc = lower_dentry->d_inode->i_op->getxattr(lower_dentry, name, value,
967 						   size);
968 	mutex_unlock(&lower_dentry->d_inode->i_mutex);
969 out:
970 	return rc;
971 }
972 
973 static ssize_t
974 ecryptfs_getxattr(struct dentry *dentry, const char *name, void *value,
975 		  size_t size)
976 {
977 	return ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry), name,
978 				       value, size);
979 }
980 
981 static ssize_t
982 ecryptfs_listxattr(struct dentry *dentry, char *list, size_t size)
983 {
984 	int rc = 0;
985 	struct dentry *lower_dentry;
986 
987 	lower_dentry = ecryptfs_dentry_to_lower(dentry);
988 	if (!lower_dentry->d_inode->i_op->listxattr) {
989 		rc = -ENOSYS;
990 		goto out;
991 	}
992 	mutex_lock(&lower_dentry->d_inode->i_mutex);
993 	rc = lower_dentry->d_inode->i_op->listxattr(lower_dentry, list, size);
994 	mutex_unlock(&lower_dentry->d_inode->i_mutex);
995 out:
996 	return rc;
997 }
998 
999 static int ecryptfs_removexattr(struct dentry *dentry, const char *name)
1000 {
1001 	int rc = 0;
1002 	struct dentry *lower_dentry;
1003 
1004 	lower_dentry = ecryptfs_dentry_to_lower(dentry);
1005 	if (!lower_dentry->d_inode->i_op->removexattr) {
1006 		rc = -ENOSYS;
1007 		goto out;
1008 	}
1009 	mutex_lock(&lower_dentry->d_inode->i_mutex);
1010 	rc = lower_dentry->d_inode->i_op->removexattr(lower_dentry, name);
1011 	mutex_unlock(&lower_dentry->d_inode->i_mutex);
1012 out:
1013 	return rc;
1014 }
1015 
1016 int ecryptfs_inode_test(struct inode *inode, void *candidate_lower_inode)
1017 {
1018 	if ((ecryptfs_inode_to_lower(inode)
1019 	     == (struct inode *)candidate_lower_inode))
1020 		return 1;
1021 	else
1022 		return 0;
1023 }
1024 
1025 int ecryptfs_inode_set(struct inode *inode, void *lower_inode)
1026 {
1027 	ecryptfs_init_inode(inode, (struct inode *)lower_inode);
1028 	return 0;
1029 }
1030 
1031 const struct inode_operations ecryptfs_symlink_iops = {
1032 	.readlink = ecryptfs_readlink,
1033 	.follow_link = ecryptfs_follow_link,
1034 	.put_link = ecryptfs_put_link,
1035 	.permission = ecryptfs_permission,
1036 	.setattr = ecryptfs_setattr,
1037 	.setxattr = ecryptfs_setxattr,
1038 	.getxattr = ecryptfs_getxattr,
1039 	.listxattr = ecryptfs_listxattr,
1040 	.removexattr = ecryptfs_removexattr
1041 };
1042 
1043 const struct inode_operations ecryptfs_dir_iops = {
1044 	.create = ecryptfs_create,
1045 	.lookup = ecryptfs_lookup,
1046 	.link = ecryptfs_link,
1047 	.unlink = ecryptfs_unlink,
1048 	.symlink = ecryptfs_symlink,
1049 	.mkdir = ecryptfs_mkdir,
1050 	.rmdir = ecryptfs_rmdir,
1051 	.mknod = ecryptfs_mknod,
1052 	.rename = ecryptfs_rename,
1053 	.permission = ecryptfs_permission,
1054 	.setattr = ecryptfs_setattr,
1055 	.setxattr = ecryptfs_setxattr,
1056 	.getxattr = ecryptfs_getxattr,
1057 	.listxattr = ecryptfs_listxattr,
1058 	.removexattr = ecryptfs_removexattr
1059 };
1060 
1061 const struct inode_operations ecryptfs_main_iops = {
1062 	.permission = ecryptfs_permission,
1063 	.setattr = ecryptfs_setattr,
1064 	.setxattr = ecryptfs_setxattr,
1065 	.getxattr = ecryptfs_getxattr,
1066 	.listxattr = ecryptfs_listxattr,
1067 	.removexattr = ecryptfs_removexattr
1068 };
1069