ecryptfs_lookup_interpose(): lower_dentry->d_parent is not stable either
[muen/linux.git] / fs / ecryptfs / inode.c
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 <asm/unaligned.h>
22 #include "ecryptfs_kernel.h"
23
24 static struct dentry *lock_parent(struct dentry *dentry)
25 {
26         struct dentry *dir;
27
28         dir = dget_parent(dentry);
29         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
30         return dir;
31 }
32
33 static void unlock_dir(struct dentry *dir)
34 {
35         inode_unlock(d_inode(dir));
36         dput(dir);
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 = ecryptfs_dentry_to_lower(dentry);
131         struct dentry *lower_dir_dentry;
132         struct inode *lower_dir_inode;
133         int rc;
134
135         lower_dir_dentry = ecryptfs_dentry_to_lower(dentry->d_parent);
136         lower_dir_inode = d_inode(lower_dir_dentry);
137         inode_lock_nested(lower_dir_inode, I_MUTEX_PARENT);
138         dget(lower_dentry);     // don't even try to make the lower negative
139         if (lower_dentry->d_parent != lower_dir_dentry)
140                 rc = -EINVAL;
141         else if (d_unhashed(lower_dentry))
142                 rc = -EINVAL;
143         else
144                 rc = vfs_unlink(lower_dir_inode, lower_dentry, NULL);
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(dir, lower_dir_inode);
150         set_nlink(inode, ecryptfs_inode_to_lower(inode)->i_nlink);
151         inode->i_ctime = dir->i_ctime;
152 out_unlock:
153         dput(lower_dentry);
154         inode_unlock(lower_dir_inode);
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  */
172 static struct inode *
173 ecryptfs_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 dentry *lower_dir_dentry;
179         struct inode *inode;
180
181         lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
182         lower_dir_dentry = lock_parent(lower_dentry);
183         rc = vfs_create(d_inode(lower_dir_dentry), lower_dentry, mode, true);
184         if (rc) {
185                 printk(KERN_ERR "%s: Failure to create dentry in lower fs; "
186                        "rc = [%d]\n", __func__, rc);
187                 inode = ERR_PTR(rc);
188                 goto out_lock;
189         }
190         inode = __ecryptfs_get_inode(d_inode(lower_dentry),
191                                      directory_inode->i_sb);
192         if (IS_ERR(inode)) {
193                 vfs_unlink(d_inode(lower_dir_dentry), lower_dentry, NULL);
194                 goto out_lock;
195         }
196         fsstack_copy_attr_times(directory_inode, d_inode(lower_dir_dentry));
197         fsstack_copy_inode_size(directory_inode, d_inode(lower_dir_dentry));
198 out_lock:
199         unlock_dir(lower_dir_dentry);
200         return inode;
201 }
202
203 /**
204  * ecryptfs_initialize_file
205  *
206  * Cause the file to be changed from a basic empty file to an ecryptfs
207  * file with a header and first data page.
208  *
209  * Returns zero on success
210  */
211 int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry,
212                              struct inode *ecryptfs_inode)
213 {
214         struct ecryptfs_crypt_stat *crypt_stat =
215                 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
216         int rc = 0;
217
218         if (S_ISDIR(ecryptfs_inode->i_mode)) {
219                 ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
220                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
221                 goto out;
222         }
223         ecryptfs_printk(KERN_DEBUG, "Initializing crypto context\n");
224         rc = ecryptfs_new_file_context(ecryptfs_inode);
225         if (rc) {
226                 ecryptfs_printk(KERN_ERR, "Error creating new file "
227                                 "context; rc = [%d]\n", rc);
228                 goto out;
229         }
230         rc = ecryptfs_get_lower_file(ecryptfs_dentry, ecryptfs_inode);
231         if (rc) {
232                 printk(KERN_ERR "%s: Error attempting to initialize "
233                         "the lower file for the dentry with name "
234                         "[%pd]; rc = [%d]\n", __func__,
235                         ecryptfs_dentry, rc);
236                 goto out;
237         }
238         rc = ecryptfs_write_metadata(ecryptfs_dentry, ecryptfs_inode);
239         if (rc)
240                 printk(KERN_ERR "Error writing headers; rc = [%d]\n", rc);
241         ecryptfs_put_lower_file(ecryptfs_inode);
242 out:
243         return rc;
244 }
245
246 /**
247  * ecryptfs_create
248  * @dir: The inode of the directory in which to create the file.
249  * @dentry: The eCryptfs dentry
250  * @mode: The mode of the new file.
251  *
252  * Creates a new file.
253  *
254  * Returns zero on success; non-zero on error condition
255  */
256 static int
257 ecryptfs_create(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(ecryptfs_inode)) {
266                 ecryptfs_printk(KERN_WARNING, "Failed to create file in"
267                                 "lower filesystem\n");
268                 rc = PTR_ERR(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(directory_inode, ecryptfs_dentry,
276                                    ecryptfs_inode);
277                 iget_failed(ecryptfs_inode);
278                 goto out;
279         }
280         d_instantiate_new(ecryptfs_dentry, ecryptfs_inode);
281 out:
282         return rc;
283 }
284
285 static 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  */
319 static struct dentry *ecryptfs_lookup_interpose(struct dentry *dentry,
320                                      struct dentry *lower_dentry)
321 {
322         struct path *path = ecryptfs_dentry_to_lower_path(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(ecryptfs_dentry_info_cache, GFP_KERNEL);
328         if (!dentry_info) {
329                 dput(lower_dentry);
330                 return ERR_PTR(-ENOMEM);
331         }
332
333         fsstack_copy_attr_atime(d_inode(dentry->d_parent),
334                                 d_inode(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(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, dentry->d_sb);
355         if (IS_ERR(inode)) {
356                 printk(KERN_ERR "%s: Error interposing; rc = [%ld]\n",
357                        __func__, PTR_ERR(inode));
358                 return ERR_CAST(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(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  */
382 static 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(ecryptfs_dentry->d_parent);
395
396         mount_crypt_stat = &ecryptfs_superblock_to_private(
397                                 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                         &encrypted_and_encoded_name, &len,
401                         mount_crypt_stat, name, 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(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(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(lower_dentry);
417         } else {
418                 res = ecryptfs_lookup_interpose(ecryptfs_dentry, lower_dentry);
419         }
420         kfree(encrypted_and_encoded_name);
421         return res;
422 }
423
424 static 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 dentry *lower_dir_dentry;
430         u64 file_size_save;
431         int rc;
432
433         file_size_save = i_size_read(d_inode(old_dentry));
434         lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
435         lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
436         dget(lower_old_dentry);
437         dget(lower_new_dentry);
438         lower_dir_dentry = lock_parent(lower_new_dentry);
439         rc = vfs_link(lower_old_dentry, d_inode(lower_dir_dentry),
440                       lower_new_dentry, NULL);
441         if (rc || d_really_is_negative(lower_new_dentry))
442                 goto out_lock;
443         rc = ecryptfs_interpose(lower_new_dentry, new_dentry, dir->i_sb);
444         if (rc)
445                 goto out_lock;
446         fsstack_copy_attr_times(dir, d_inode(lower_dir_dentry));
447         fsstack_copy_inode_size(dir, d_inode(lower_dir_dentry));
448         set_nlink(d_inode(old_dentry),
449                   ecryptfs_inode_to_lower(d_inode(old_dentry))->i_nlink);
450         i_size_write(d_inode(new_dentry), file_size_save);
451 out_lock:
452         unlock_dir(lower_dir_dentry);
453         dput(lower_new_dentry);
454         dput(lower_old_dentry);
455         return rc;
456 }
457
458 static int ecryptfs_unlink(struct inode *dir, struct dentry *dentry)
459 {
460         return ecryptfs_do_unlink(dir, dentry, d_inode(dentry));
461 }
462
463 static int ecryptfs_symlink(struct inode *dir, struct dentry *dentry,
464                             const char *symname)
465 {
466         int rc;
467         struct dentry *lower_dentry;
468         struct dentry *lower_dir_dentry;
469         char *encoded_symname;
470         size_t encoded_symlen;
471         struct ecryptfs_mount_crypt_stat *mount_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         mount_crypt_stat = &ecryptfs_superblock_to_private(
477                 dir->i_sb)->mount_crypt_stat;
478         rc = ecryptfs_encrypt_and_encode_filename(&encoded_symname,
479                                                   &encoded_symlen,
480                                                   mount_crypt_stat, symname,
481                                                   strlen(symname));
482         if (rc)
483                 goto out_lock;
484         rc = vfs_symlink(d_inode(lower_dir_dentry), lower_dentry,
485                          encoded_symname);
486         kfree(encoded_symname);
487         if (rc || d_really_is_negative(lower_dentry))
488                 goto out_lock;
489         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
490         if (rc)
491                 goto out_lock;
492         fsstack_copy_attr_times(dir, d_inode(lower_dir_dentry));
493         fsstack_copy_inode_size(dir, d_inode(lower_dir_dentry));
494 out_lock:
495         unlock_dir(lower_dir_dentry);
496         dput(lower_dentry);
497         if (d_really_is_negative(dentry))
498                 d_drop(dentry);
499         return rc;
500 }
501
502 static int ecryptfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t 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(d_inode(lower_dir_dentry), lower_dentry, mode);
511         if (rc || d_really_is_negative(lower_dentry))
512                 goto out;
513         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
514         if (rc)
515                 goto out;
516         fsstack_copy_attr_times(dir, d_inode(lower_dir_dentry));
517         fsstack_copy_inode_size(dir, d_inode(lower_dir_dentry));
518         set_nlink(dir, d_inode(lower_dir_dentry)->i_nlink);
519 out:
520         unlock_dir(lower_dir_dentry);
521         if (d_really_is_negative(dentry))
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         struct inode *lower_dir_inode;
531         int rc;
532
533         lower_dentry = ecryptfs_dentry_to_lower(dentry);
534         lower_dir_dentry = ecryptfs_dentry_to_lower(dentry->d_parent);
535         lower_dir_inode = d_inode(lower_dir_dentry);
536
537         inode_lock_nested(lower_dir_inode, I_MUTEX_PARENT);
538         dget(lower_dentry);     // don't even try to make the lower negative
539         if (lower_dentry->d_parent != lower_dir_dentry)
540                 rc = -EINVAL;
541         else if (d_unhashed(lower_dentry))
542                 rc = -EINVAL;
543         else
544                 rc = vfs_rmdir(lower_dir_inode, lower_dentry);
545         if (!rc) {
546                 clear_nlink(d_inode(dentry));
547                 fsstack_copy_attr_times(dir, lower_dir_inode);
548                 set_nlink(dir, lower_dir_inode->i_nlink);
549         }
550         dput(lower_dentry);
551         inode_unlock(lower_dir_inode);
552         if (!rc)
553                 d_drop(dentry);
554         return rc;
555 }
556
557 static int
558 ecryptfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
559 {
560         int rc;
561         struct dentry *lower_dentry;
562         struct dentry *lower_dir_dentry;
563
564         lower_dentry = ecryptfs_dentry_to_lower(dentry);
565         lower_dir_dentry = lock_parent(lower_dentry);
566         rc = vfs_mknod(d_inode(lower_dir_dentry), lower_dentry, mode, dev);
567         if (rc || d_really_is_negative(lower_dentry))
568                 goto out;
569         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
570         if (rc)
571                 goto out;
572         fsstack_copy_attr_times(dir, d_inode(lower_dir_dentry));
573         fsstack_copy_inode_size(dir, d_inode(lower_dir_dentry));
574 out:
575         unlock_dir(lower_dir_dentry);
576         if (d_really_is_negative(dentry))
577                 d_drop(dentry);
578         return rc;
579 }
580
581 static int
582 ecryptfs_rename(struct inode *old_dir, struct dentry *old_dentry,
583                 struct inode *new_dir, struct dentry *new_dentry,
584                 unsigned int flags)
585 {
586         int rc;
587         struct dentry *lower_old_dentry;
588         struct dentry *lower_new_dentry;
589         struct dentry *lower_old_dir_dentry;
590         struct dentry *lower_new_dir_dentry;
591         struct dentry *trap;
592         struct inode *target_inode;
593
594         if (flags)
595                 return -EINVAL;
596
597         lower_old_dir_dentry = ecryptfs_dentry_to_lower(old_dentry->d_parent);
598         lower_new_dir_dentry = ecryptfs_dentry_to_lower(new_dentry->d_parent);
599
600         lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
601         lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
602
603         target_inode = d_inode(new_dentry);
604
605         trap = lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
606         dget(lower_new_dentry);
607         rc = -EINVAL;
608         if (lower_old_dentry->d_parent != lower_old_dir_dentry)
609                 goto out_lock;
610         if (lower_new_dentry->d_parent != lower_new_dir_dentry)
611                 goto out_lock;
612         if (d_unhashed(lower_old_dentry) || d_unhashed(lower_new_dentry))
613                 goto out_lock;
614         /* source should not be ancestor of target */
615         if (trap == lower_old_dentry)
616                 goto out_lock;
617         /* target should not be ancestor of source */
618         if (trap == lower_new_dentry) {
619                 rc = -ENOTEMPTY;
620                 goto out_lock;
621         }
622         rc = vfs_rename(d_inode(lower_old_dir_dentry), lower_old_dentry,
623                         d_inode(lower_new_dir_dentry), lower_new_dentry,
624                         NULL, 0);
625         if (rc)
626                 goto out_lock;
627         if (target_inode)
628                 fsstack_copy_attr_all(target_inode,
629                                       ecryptfs_inode_to_lower(target_inode));
630         fsstack_copy_attr_all(new_dir, d_inode(lower_new_dir_dentry));
631         if (new_dir != old_dir)
632                 fsstack_copy_attr_all(old_dir, d_inode(lower_old_dir_dentry));
633 out_lock:
634         dput(lower_new_dentry);
635         unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
636         return rc;
637 }
638
639 static char *ecryptfs_readlink_lower(struct dentry *dentry, size_t *bufsiz)
640 {
641         DEFINE_DELAYED_CALL(done);
642         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
643         const char *link;
644         char *buf;
645         int rc;
646
647         link = vfs_get_link(lower_dentry, &done);
648         if (IS_ERR(link))
649                 return ERR_CAST(link);
650
651         rc = ecryptfs_decode_and_decrypt_filename(&buf, bufsiz, dentry->d_sb,
652                                                   link, strlen(link));
653         do_delayed_call(&done);
654         if (rc)
655                 return ERR_PTR(rc);
656
657         return buf;
658 }
659
660 static const char *ecryptfs_get_link(struct dentry *dentry,
661                                      struct inode *inode,
662                                      struct delayed_call *done)
663 {
664         size_t len;
665         char *buf;
666
667         if (!dentry)
668                 return ERR_PTR(-ECHILD);
669
670         buf = ecryptfs_readlink_lower(dentry, &len);
671         if (IS_ERR(buf))
672                 return buf;
673         fsstack_copy_attr_atime(d_inode(dentry),
674                                 d_inode(ecryptfs_dentry_to_lower(dentry)));
675         buf[len] = '\0';
676         set_delayed_call(done, kfree_link, buf);
677         return buf;
678 }
679
680 /**
681  * upper_size_to_lower_size
682  * @crypt_stat: Crypt_stat associated with file
683  * @upper_size: Size of the upper file
684  *
685  * Calculate the required size of the lower file based on the
686  * specified size of the upper file. This calculation is based on the
687  * number of headers in the underlying file and the extent size.
688  *
689  * Returns Calculated size of the lower file.
690  */
691 static loff_t
692 upper_size_to_lower_size(struct ecryptfs_crypt_stat *crypt_stat,
693                          loff_t upper_size)
694 {
695         loff_t lower_size;
696
697         lower_size = ecryptfs_lower_header_size(crypt_stat);
698         if (upper_size != 0) {
699                 loff_t num_extents;
700
701                 num_extents = upper_size >> crypt_stat->extent_shift;
702                 if (upper_size & ~crypt_stat->extent_mask)
703                         num_extents++;
704                 lower_size += (num_extents * crypt_stat->extent_size);
705         }
706         return lower_size;
707 }
708
709 /**
710  * truncate_upper
711  * @dentry: The ecryptfs layer dentry
712  * @ia: Address of the ecryptfs inode's attributes
713  * @lower_ia: Address of the lower inode's attributes
714  *
715  * Function to handle truncations modifying the size of the file. Note
716  * that the file sizes are interpolated. When expanding, we are simply
717  * writing strings of 0's out. When truncating, we truncate the upper
718  * inode and update the lower_ia according to the page index
719  * interpolations. If ATTR_SIZE is set in lower_ia->ia_valid upon return,
720  * the caller must use lower_ia in a call to notify_change() to perform
721  * the truncation of the lower inode.
722  *
723  * Returns zero on success; non-zero otherwise
724  */
725 static int truncate_upper(struct dentry *dentry, struct iattr *ia,
726                           struct iattr *lower_ia)
727 {
728         int rc = 0;
729         struct inode *inode = d_inode(dentry);
730         struct ecryptfs_crypt_stat *crypt_stat;
731         loff_t i_size = i_size_read(inode);
732         loff_t lower_size_before_truncate;
733         loff_t lower_size_after_truncate;
734
735         if (unlikely((ia->ia_size == i_size))) {
736                 lower_ia->ia_valid &= ~ATTR_SIZE;
737                 return 0;
738         }
739         rc = ecryptfs_get_lower_file(dentry, inode);
740         if (rc)
741                 return rc;
742         crypt_stat = &ecryptfs_inode_to_private(d_inode(dentry))->crypt_stat;
743         /* Switch on growing or shrinking file */
744         if (ia->ia_size > i_size) {
745                 char zero[] = { 0x00 };
746
747                 lower_ia->ia_valid &= ~ATTR_SIZE;
748                 /* Write a single 0 at the last position of the file;
749                  * this triggers code that will fill in 0's throughout
750                  * the intermediate portion of the previous end of the
751                  * file and the new and of the file */
752                 rc = ecryptfs_write(inode, zero,
753                                     (ia->ia_size - 1), 1);
754         } else { /* ia->ia_size < i_size_read(inode) */
755                 /* We're chopping off all the pages down to the page
756                  * in which ia->ia_size is located. Fill in the end of
757                  * that page from (ia->ia_size & ~PAGE_MASK) to
758                  * PAGE_SIZE with zeros. */
759                 size_t num_zeros = (PAGE_SIZE
760                                     - (ia->ia_size & ~PAGE_MASK));
761
762                 if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
763                         truncate_setsize(inode, ia->ia_size);
764                         lower_ia->ia_size = ia->ia_size;
765                         lower_ia->ia_valid |= ATTR_SIZE;
766                         goto out;
767                 }
768                 if (num_zeros) {
769                         char *zeros_virt;
770
771                         zeros_virt = kzalloc(num_zeros, GFP_KERNEL);
772                         if (!zeros_virt) {
773                                 rc = -ENOMEM;
774                                 goto out;
775                         }
776                         rc = ecryptfs_write(inode, zeros_virt,
777                                             ia->ia_size, num_zeros);
778                         kfree(zeros_virt);
779                         if (rc) {
780                                 printk(KERN_ERR "Error attempting to zero out "
781                                        "the remainder of the end page on "
782                                        "reducing truncate; rc = [%d]\n", rc);
783                                 goto out;
784                         }
785                 }
786                 truncate_setsize(inode, ia->ia_size);
787                 rc = ecryptfs_write_inode_size_to_metadata(inode);
788                 if (rc) {
789                         printk(KERN_ERR "Problem with "
790                                "ecryptfs_write_inode_size_to_metadata; "
791                                "rc = [%d]\n", rc);
792                         goto out;
793                 }
794                 /* We are reducing the size of the ecryptfs file, and need to
795                  * know if we need to reduce the size of the lower file. */
796                 lower_size_before_truncate =
797                     upper_size_to_lower_size(crypt_stat, i_size);
798                 lower_size_after_truncate =
799                     upper_size_to_lower_size(crypt_stat, ia->ia_size);
800                 if (lower_size_after_truncate < lower_size_before_truncate) {
801                         lower_ia->ia_size = lower_size_after_truncate;
802                         lower_ia->ia_valid |= ATTR_SIZE;
803                 } else
804                         lower_ia->ia_valid &= ~ATTR_SIZE;
805         }
806 out:
807         ecryptfs_put_lower_file(inode);
808         return rc;
809 }
810
811 static int ecryptfs_inode_newsize_ok(struct inode *inode, loff_t offset)
812 {
813         struct ecryptfs_crypt_stat *crypt_stat;
814         loff_t lower_oldsize, lower_newsize;
815
816         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
817         lower_oldsize = upper_size_to_lower_size(crypt_stat,
818                                                  i_size_read(inode));
819         lower_newsize = upper_size_to_lower_size(crypt_stat, offset);
820         if (lower_newsize > lower_oldsize) {
821                 /*
822                  * The eCryptfs inode and the new *lower* size are mixed here
823                  * because we may not have the lower i_mutex held and/or it may
824                  * not be appropriate to call inode_newsize_ok() with inodes
825                  * from other filesystems.
826                  */
827                 return inode_newsize_ok(inode, lower_newsize);
828         }
829
830         return 0;
831 }
832
833 /**
834  * ecryptfs_truncate
835  * @dentry: The ecryptfs layer dentry
836  * @new_length: The length to expand the file to
837  *
838  * Simple function that handles the truncation of an eCryptfs inode and
839  * its corresponding lower inode.
840  *
841  * Returns zero on success; non-zero otherwise
842  */
843 int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
844 {
845         struct iattr ia = { .ia_valid = ATTR_SIZE, .ia_size = new_length };
846         struct iattr lower_ia = { .ia_valid = 0 };
847         int rc;
848
849         rc = ecryptfs_inode_newsize_ok(d_inode(dentry), new_length);
850         if (rc)
851                 return rc;
852
853         rc = truncate_upper(dentry, &ia, &lower_ia);
854         if (!rc && lower_ia.ia_valid & ATTR_SIZE) {
855                 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
856
857                 inode_lock(d_inode(lower_dentry));
858                 rc = notify_change(lower_dentry, &lower_ia, NULL);
859                 inode_unlock(d_inode(lower_dentry));
860         }
861         return rc;
862 }
863
864 static int
865 ecryptfs_permission(struct inode *inode, int mask)
866 {
867         return inode_permission(ecryptfs_inode_to_lower(inode), mask);
868 }
869
870 /**
871  * ecryptfs_setattr
872  * @dentry: dentry handle to the inode to modify
873  * @ia: Structure with flags of what to change and values
874  *
875  * Updates the metadata of an inode. If the update is to the size
876  * i.e. truncation, then ecryptfs_truncate will handle the size modification
877  * of both the ecryptfs inode and the lower inode.
878  *
879  * All other metadata changes will be passed right to the lower filesystem,
880  * and we will just update our inode to look like the lower.
881  */
882 static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
883 {
884         int rc = 0;
885         struct dentry *lower_dentry;
886         struct iattr lower_ia;
887         struct inode *inode;
888         struct inode *lower_inode;
889         struct ecryptfs_crypt_stat *crypt_stat;
890
891         crypt_stat = &ecryptfs_inode_to_private(d_inode(dentry))->crypt_stat;
892         if (!(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED)) {
893                 rc = ecryptfs_init_crypt_stat(crypt_stat);
894                 if (rc)
895                         return rc;
896         }
897         inode = d_inode(dentry);
898         lower_inode = ecryptfs_inode_to_lower(inode);
899         lower_dentry = ecryptfs_dentry_to_lower(dentry);
900         mutex_lock(&crypt_stat->cs_mutex);
901         if (d_is_dir(dentry))
902                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
903         else if (d_is_reg(dentry)
904                  && (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
905                      || !(crypt_stat->flags & ECRYPTFS_KEY_VALID))) {
906                 struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
907
908                 mount_crypt_stat = &ecryptfs_superblock_to_private(
909                         dentry->d_sb)->mount_crypt_stat;
910                 rc = ecryptfs_get_lower_file(dentry, inode);
911                 if (rc) {
912                         mutex_unlock(&crypt_stat->cs_mutex);
913                         goto out;
914                 }
915                 rc = ecryptfs_read_metadata(dentry);
916                 ecryptfs_put_lower_file(inode);
917                 if (rc) {
918                         if (!(mount_crypt_stat->flags
919                               & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
920                                 rc = -EIO;
921                                 printk(KERN_WARNING "Either the lower file "
922                                        "is not in a valid eCryptfs format, "
923                                        "or the key could not be retrieved. "
924                                        "Plaintext passthrough mode is not "
925                                        "enabled; returning -EIO\n");
926                                 mutex_unlock(&crypt_stat->cs_mutex);
927                                 goto out;
928                         }
929                         rc = 0;
930                         crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
931                                                | ECRYPTFS_ENCRYPTED);
932                 }
933         }
934         mutex_unlock(&crypt_stat->cs_mutex);
935
936         rc = setattr_prepare(dentry, ia);
937         if (rc)
938                 goto out;
939         if (ia->ia_valid & ATTR_SIZE) {
940                 rc = ecryptfs_inode_newsize_ok(inode, ia->ia_size);
941                 if (rc)
942                         goto out;
943         }
944
945         memcpy(&lower_ia, ia, sizeof(lower_ia));
946         if (ia->ia_valid & ATTR_FILE)
947                 lower_ia.ia_file = ecryptfs_file_to_lower(ia->ia_file);
948         if (ia->ia_valid & ATTR_SIZE) {
949                 rc = truncate_upper(dentry, ia, &lower_ia);
950                 if (rc < 0)
951                         goto out;
952         }
953
954         /*
955          * mode change is for clearing setuid/setgid bits. Allow lower fs
956          * to interpret this in its own way.
957          */
958         if (lower_ia.ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
959                 lower_ia.ia_valid &= ~ATTR_MODE;
960
961         inode_lock(d_inode(lower_dentry));
962         rc = notify_change(lower_dentry, &lower_ia, NULL);
963         inode_unlock(d_inode(lower_dentry));
964 out:
965         fsstack_copy_attr_all(inode, lower_inode);
966         return rc;
967 }
968
969 static int ecryptfs_getattr_link(const struct path *path, struct kstat *stat,
970                                  u32 request_mask, unsigned int flags)
971 {
972         struct dentry *dentry = path->dentry;
973         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
974         int rc = 0;
975
976         mount_crypt_stat = &ecryptfs_superblock_to_private(
977                                                 dentry->d_sb)->mount_crypt_stat;
978         generic_fillattr(d_inode(dentry), stat);
979         if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
980                 char *target;
981                 size_t targetsiz;
982
983                 target = ecryptfs_readlink_lower(dentry, &targetsiz);
984                 if (!IS_ERR(target)) {
985                         kfree(target);
986                         stat->size = targetsiz;
987                 } else {
988                         rc = PTR_ERR(target);
989                 }
990         }
991         return rc;
992 }
993
994 static int ecryptfs_getattr(const struct path *path, struct kstat *stat,
995                             u32 request_mask, unsigned int flags)
996 {
997         struct dentry *dentry = path->dentry;
998         struct kstat lower_stat;
999         int rc;
1000
1001         rc = vfs_getattr(ecryptfs_dentry_to_lower_path(dentry), &lower_stat,
1002                          request_mask, flags);
1003         if (!rc) {
1004                 fsstack_copy_attr_all(d_inode(dentry),
1005                                       ecryptfs_inode_to_lower(d_inode(dentry)));
1006                 generic_fillattr(d_inode(dentry), stat);
1007                 stat->blocks = lower_stat.blocks;
1008         }
1009         return rc;
1010 }
1011
1012 int
1013 ecryptfs_setxattr(struct dentry *dentry, struct inode *inode,
1014                   const char *name, const void *value,
1015                   size_t size, int flags)
1016 {
1017         int rc;
1018         struct dentry *lower_dentry;
1019
1020         lower_dentry = ecryptfs_dentry_to_lower(dentry);
1021         if (!(d_inode(lower_dentry)->i_opflags & IOP_XATTR)) {
1022                 rc = -EOPNOTSUPP;
1023                 goto out;
1024         }
1025         rc = vfs_setxattr(lower_dentry, name, value, size, flags);
1026         if (!rc && inode)
1027                 fsstack_copy_attr_all(inode, d_inode(lower_dentry));
1028 out:
1029         return rc;
1030 }
1031
1032 ssize_t
1033 ecryptfs_getxattr_lower(struct dentry *lower_dentry, struct inode *lower_inode,
1034                         const char *name, void *value, size_t size)
1035 {
1036         int rc;
1037
1038         if (!(lower_inode->i_opflags & IOP_XATTR)) {
1039                 rc = -EOPNOTSUPP;
1040                 goto out;
1041         }
1042         inode_lock(lower_inode);
1043         rc = __vfs_getxattr(lower_dentry, lower_inode, name, value, size);
1044         inode_unlock(lower_inode);
1045 out:
1046         return rc;
1047 }
1048
1049 static ssize_t
1050 ecryptfs_getxattr(struct dentry *dentry, struct inode *inode,
1051                   const char *name, void *value, size_t size)
1052 {
1053         return ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
1054                                        ecryptfs_inode_to_lower(inode),
1055                                        name, value, size);
1056 }
1057
1058 static ssize_t
1059 ecryptfs_listxattr(struct dentry *dentry, char *list, size_t size)
1060 {
1061         int rc = 0;
1062         struct dentry *lower_dentry;
1063
1064         lower_dentry = ecryptfs_dentry_to_lower(dentry);
1065         if (!d_inode(lower_dentry)->i_op->listxattr) {
1066                 rc = -EOPNOTSUPP;
1067                 goto out;
1068         }
1069         inode_lock(d_inode(lower_dentry));
1070         rc = d_inode(lower_dentry)->i_op->listxattr(lower_dentry, list, size);
1071         inode_unlock(d_inode(lower_dentry));
1072 out:
1073         return rc;
1074 }
1075
1076 static int ecryptfs_removexattr(struct dentry *dentry, struct inode *inode,
1077                                 const char *name)
1078 {
1079         int rc;
1080         struct dentry *lower_dentry;
1081         struct inode *lower_inode;
1082
1083         lower_dentry = ecryptfs_dentry_to_lower(dentry);
1084         lower_inode = ecryptfs_inode_to_lower(inode);
1085         if (!(lower_inode->i_opflags & IOP_XATTR)) {
1086                 rc = -EOPNOTSUPP;
1087                 goto out;
1088         }
1089         inode_lock(lower_inode);
1090         rc = __vfs_removexattr(lower_dentry, name);
1091         inode_unlock(lower_inode);
1092 out:
1093         return rc;
1094 }
1095
1096 const struct inode_operations ecryptfs_symlink_iops = {
1097         .get_link = ecryptfs_get_link,
1098         .permission = ecryptfs_permission,
1099         .setattr = ecryptfs_setattr,
1100         .getattr = ecryptfs_getattr_link,
1101         .listxattr = ecryptfs_listxattr,
1102 };
1103
1104 const struct inode_operations ecryptfs_dir_iops = {
1105         .create = ecryptfs_create,
1106         .lookup = ecryptfs_lookup,
1107         .link = ecryptfs_link,
1108         .unlink = ecryptfs_unlink,
1109         .symlink = ecryptfs_symlink,
1110         .mkdir = ecryptfs_mkdir,
1111         .rmdir = ecryptfs_rmdir,
1112         .mknod = ecryptfs_mknod,
1113         .rename = ecryptfs_rename,
1114         .permission = ecryptfs_permission,
1115         .setattr = ecryptfs_setattr,
1116         .listxattr = ecryptfs_listxattr,
1117 };
1118
1119 const struct inode_operations ecryptfs_main_iops = {
1120         .permission = ecryptfs_permission,
1121         .setattr = ecryptfs_setattr,
1122         .getattr = ecryptfs_getattr,
1123         .listxattr = ecryptfs_listxattr,
1124 };
1125
1126 static int ecryptfs_xattr_get(const struct xattr_handler *handler,
1127                               struct dentry *dentry, struct inode *inode,
1128                               const char *name, void *buffer, size_t size)
1129 {
1130         return ecryptfs_getxattr(dentry, inode, name, buffer, size);
1131 }
1132
1133 static int ecryptfs_xattr_set(const struct xattr_handler *handler,
1134                               struct dentry *dentry, struct inode *inode,
1135                               const char *name, const void *value, size_t size,
1136                               int flags)
1137 {
1138         if (value)
1139                 return ecryptfs_setxattr(dentry, inode, name, value, size, flags);
1140         else {
1141                 BUG_ON(flags != XATTR_REPLACE);
1142                 return ecryptfs_removexattr(dentry, inode, name);
1143         }
1144 }
1145
1146 static const struct xattr_handler ecryptfs_xattr_handler = {
1147         .prefix = "",  /* match anything */
1148         .get = ecryptfs_xattr_get,
1149         .set = ecryptfs_xattr_set,
1150 };
1151
1152 const struct xattr_handler *ecryptfs_xattr_handlers[] = {
1153         &ecryptfs_xattr_handler,
1154         NULL
1155 };