get rid of pointless allocations and copying in ecryptfs_follow_link()
[linux-3.10.git] / fs / ecryptfs / inode.c
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 <linux/slab.h>
35 #include <linux/xattr.h>
36 #include <asm/unaligned.h>
37 #include "ecryptfs_kernel.h"
38
39 static struct dentry *lock_parent(struct dentry *dentry)
40 {
41         struct dentry *dir;
42
43         dir = dget_parent(dentry);
44         mutex_lock_nested(&(dir->d_inode->i_mutex), I_MUTEX_PARENT);
45         return dir;
46 }
47
48 static void unlock_dir(struct dentry *dir)
49 {
50         mutex_unlock(&dir->d_inode->i_mutex);
51         dput(dir);
52 }
53
54 static int ecryptfs_inode_test(struct inode *inode, void *lower_inode)
55 {
56         if (ecryptfs_inode_to_lower(inode) == (struct inode *)lower_inode)
57                 return 1;
58         return 0;
59 }
60
61 static int ecryptfs_inode_set(struct inode *inode, void *opaque)
62 {
63         struct inode *lower_inode = opaque;
64
65         ecryptfs_set_inode_lower(inode, lower_inode);
66         fsstack_copy_attr_all(inode, lower_inode);
67         /* i_size will be overwritten for encrypted regular files */
68         fsstack_copy_inode_size(inode, lower_inode);
69         inode->i_ino = lower_inode->i_ino;
70         inode->i_version++;
71         inode->i_mapping->a_ops = &ecryptfs_aops;
72         inode->i_mapping->backing_dev_info = inode->i_sb->s_bdi;
73
74         if (S_ISLNK(inode->i_mode))
75                 inode->i_op = &ecryptfs_symlink_iops;
76         else if (S_ISDIR(inode->i_mode))
77                 inode->i_op = &ecryptfs_dir_iops;
78         else
79                 inode->i_op = &ecryptfs_main_iops;
80
81         if (S_ISDIR(inode->i_mode))
82                 inode->i_fop = &ecryptfs_dir_fops;
83         else if (special_file(inode->i_mode))
84                 init_special_inode(inode, inode->i_mode, inode->i_rdev);
85         else
86                 inode->i_fop = &ecryptfs_main_fops;
87
88         return 0;
89 }
90
91 static struct inode *__ecryptfs_get_inode(struct inode *lower_inode,
92                                           struct super_block *sb)
93 {
94         struct inode *inode;
95
96         if (lower_inode->i_sb != ecryptfs_superblock_to_lower(sb))
97                 return ERR_PTR(-EXDEV);
98         if (!igrab(lower_inode))
99                 return ERR_PTR(-ESTALE);
100         inode = iget5_locked(sb, (unsigned long)lower_inode,
101                              ecryptfs_inode_test, ecryptfs_inode_set,
102                              lower_inode);
103         if (!inode) {
104                 iput(lower_inode);
105                 return ERR_PTR(-EACCES);
106         }
107         if (!(inode->i_state & I_NEW))
108                 iput(lower_inode);
109
110         return inode;
111 }
112
113 struct inode *ecryptfs_get_inode(struct inode *lower_inode,
114                                  struct super_block *sb)
115 {
116         struct inode *inode = __ecryptfs_get_inode(lower_inode, sb);
117
118         if (!IS_ERR(inode) && (inode->i_state & I_NEW))
119                 unlock_new_inode(inode);
120
121         return inode;
122 }
123
124 /**
125  * ecryptfs_interpose
126  * @lower_dentry: Existing dentry in the lower filesystem
127  * @dentry: ecryptfs' dentry
128  * @sb: ecryptfs's super_block
129  *
130  * Interposes upper and lower dentries.
131  *
132  * Returns zero on success; non-zero otherwise
133  */
134 static int ecryptfs_interpose(struct dentry *lower_dentry,
135                               struct dentry *dentry, struct super_block *sb)
136 {
137         struct inode *inode = ecryptfs_get_inode(lower_dentry->d_inode, sb);
138
139         if (IS_ERR(inode))
140                 return PTR_ERR(inode);
141         d_instantiate(dentry, inode);
142
143         return 0;
144 }
145
146 /**
147  * ecryptfs_do_create
148  * @directory_inode: inode of the new file's dentry's parent in ecryptfs
149  * @ecryptfs_dentry: New file's dentry in ecryptfs
150  * @mode: The mode of the new file
151  * @nd: nameidata of ecryptfs' parent's dentry & vfsmount
152  *
153  * Creates the underlying file and the eCryptfs inode which will link to
154  * it. It will also update the eCryptfs directory inode to mimic the
155  * stat of the lower directory inode.
156  *
157  * Returns the new eCryptfs inode on success; an ERR_PTR on error condition
158  */
159 static struct inode *
160 ecryptfs_do_create(struct inode *directory_inode,
161                    struct dentry *ecryptfs_dentry, umode_t mode)
162 {
163         int rc;
164         struct dentry *lower_dentry;
165         struct dentry *lower_dir_dentry;
166         struct inode *inode;
167
168         lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
169         lower_dir_dentry = lock_parent(lower_dentry);
170         if (IS_ERR(lower_dir_dentry)) {
171                 ecryptfs_printk(KERN_ERR, "Error locking directory of "
172                                 "dentry\n");
173                 inode = ERR_CAST(lower_dir_dentry);
174                 goto out;
175         }
176         rc = vfs_create(lower_dir_dentry->d_inode, lower_dentry, mode, NULL);
177         if (rc) {
178                 printk(KERN_ERR "%s: Failure to create dentry in lower fs; "
179                        "rc = [%d]\n", __func__, rc);
180                 inode = ERR_PTR(rc);
181                 goto out_lock;
182         }
183         inode = __ecryptfs_get_inode(lower_dentry->d_inode,
184                                      directory_inode->i_sb);
185         if (IS_ERR(inode))
186                 goto out_lock;
187         fsstack_copy_attr_times(directory_inode, lower_dir_dentry->d_inode);
188         fsstack_copy_inode_size(directory_inode, lower_dir_dentry->d_inode);
189 out_lock:
190         unlock_dir(lower_dir_dentry);
191 out:
192         return inode;
193 }
194
195 /**
196  * ecryptfs_initialize_file
197  *
198  * Cause the file to be changed from a basic empty file to an ecryptfs
199  * file with a header and first data page.
200  *
201  * Returns zero on success
202  */
203 static int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry,
204                                     struct inode *ecryptfs_inode)
205 {
206         struct ecryptfs_crypt_stat *crypt_stat =
207                 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
208         int rc = 0;
209
210         if (S_ISDIR(ecryptfs_inode->i_mode)) {
211                 ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
212                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
213                 goto out;
214         }
215         ecryptfs_printk(KERN_DEBUG, "Initializing crypto context\n");
216         rc = ecryptfs_new_file_context(ecryptfs_inode);
217         if (rc) {
218                 ecryptfs_printk(KERN_ERR, "Error creating new file "
219                                 "context; rc = [%d]\n", rc);
220                 goto out;
221         }
222         rc = ecryptfs_get_lower_file(ecryptfs_dentry, ecryptfs_inode);
223         if (rc) {
224                 printk(KERN_ERR "%s: Error attempting to initialize "
225                         "the lower file for the dentry with name "
226                         "[%s]; rc = [%d]\n", __func__,
227                         ecryptfs_dentry->d_name.name, rc);
228                 goto out;
229         }
230         rc = ecryptfs_write_metadata(ecryptfs_dentry, ecryptfs_inode);
231         if (rc)
232                 printk(KERN_ERR "Error writing headers; rc = [%d]\n", rc);
233         ecryptfs_put_lower_file(ecryptfs_inode);
234 out:
235         return rc;
236 }
237
238 /**
239  * ecryptfs_create
240  * @dir: The inode of the directory in which to create the file.
241  * @dentry: The eCryptfs dentry
242  * @mode: The mode of the new file.
243  * @nd: nameidata
244  *
245  * Creates a new file.
246  *
247  * Returns zero on success; non-zero on error condition
248  */
249 static int
250 ecryptfs_create(struct inode *directory_inode, struct dentry *ecryptfs_dentry,
251                 umode_t mode, struct nameidata *nd)
252 {
253         struct inode *ecryptfs_inode;
254         int rc;
255
256         ecryptfs_inode = ecryptfs_do_create(directory_inode, ecryptfs_dentry,
257                                             mode);
258         if (unlikely(IS_ERR(ecryptfs_inode))) {
259                 ecryptfs_printk(KERN_WARNING, "Failed to create file in"
260                                 "lower filesystem\n");
261                 rc = PTR_ERR(ecryptfs_inode);
262                 goto out;
263         }
264         /* At this point, a file exists on "disk"; we need to make sure
265          * that this on disk file is prepared to be an ecryptfs file */
266         rc = ecryptfs_initialize_file(ecryptfs_dentry, ecryptfs_inode);
267         if (rc) {
268                 drop_nlink(ecryptfs_inode);
269                 unlock_new_inode(ecryptfs_inode);
270                 iput(ecryptfs_inode);
271                 goto out;
272         }
273         d_instantiate(ecryptfs_dentry, ecryptfs_inode);
274         unlock_new_inode(ecryptfs_inode);
275 out:
276         return rc;
277 }
278
279 static int ecryptfs_i_size_read(struct dentry *dentry, struct inode *inode)
280 {
281         struct ecryptfs_crypt_stat *crypt_stat;
282         int rc;
283
284         rc = ecryptfs_get_lower_file(dentry, inode);
285         if (rc) {
286                 printk(KERN_ERR "%s: Error attempting to initialize "
287                         "the lower file for the dentry with name "
288                         "[%s]; rc = [%d]\n", __func__,
289                         dentry->d_name.name, rc);
290                 return rc;
291         }
292
293         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
294         /* TODO: lock for crypt_stat comparison */
295         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED))
296                 ecryptfs_set_default_sizes(crypt_stat);
297
298         rc = ecryptfs_read_and_validate_header_region(inode);
299         ecryptfs_put_lower_file(inode);
300         if (rc) {
301                 rc = ecryptfs_read_and_validate_xattr_region(dentry, inode);
302                 if (!rc)
303                         crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
304         }
305
306         /* Must return 0 to allow non-eCryptfs files to be looked up, too */
307         return 0;
308 }
309
310 /**
311  * ecryptfs_lookup_interpose - Dentry interposition for a lookup
312  */
313 static int ecryptfs_lookup_interpose(struct dentry *dentry,
314                                      struct dentry *lower_dentry,
315                                      struct inode *dir_inode)
316 {
317         struct inode *inode, *lower_inode = lower_dentry->d_inode;
318         struct ecryptfs_dentry_info *dentry_info;
319         struct vfsmount *lower_mnt;
320         int rc = 0;
321
322         lower_mnt = mntget(ecryptfs_dentry_to_lower_mnt(dentry->d_parent));
323         fsstack_copy_attr_atime(dir_inode, lower_dentry->d_parent->d_inode);
324         BUG_ON(!lower_dentry->d_count);
325
326         dentry_info = kmem_cache_alloc(ecryptfs_dentry_info_cache, GFP_KERNEL);
327         ecryptfs_set_dentry_private(dentry, dentry_info);
328         if (!dentry_info) {
329                 printk(KERN_ERR "%s: Out of memory whilst attempting "
330                        "to allocate ecryptfs_dentry_info struct\n",
331                         __func__);
332                 dput(lower_dentry);
333                 mntput(lower_mnt);
334                 d_drop(dentry);
335                 return -ENOMEM;
336         }
337         ecryptfs_set_dentry_lower(dentry, lower_dentry);
338         ecryptfs_set_dentry_lower_mnt(dentry, lower_mnt);
339
340         if (!lower_dentry->d_inode) {
341                 /* We want to add because we couldn't find in lower */
342                 d_add(dentry, NULL);
343                 return 0;
344         }
345         inode = __ecryptfs_get_inode(lower_inode, dir_inode->i_sb);
346         if (IS_ERR(inode)) {
347                 printk(KERN_ERR "%s: Error interposing; rc = [%ld]\n",
348                        __func__, PTR_ERR(inode));
349                 return PTR_ERR(inode);
350         }
351         if (S_ISREG(inode->i_mode)) {
352                 rc = ecryptfs_i_size_read(dentry, inode);
353                 if (rc) {
354                         make_bad_inode(inode);
355                         return rc;
356                 }
357         }
358
359         if (inode->i_state & I_NEW)
360                 unlock_new_inode(inode);
361         d_add(dentry, inode);
362
363         return rc;
364 }
365
366 /**
367  * ecryptfs_lookup
368  * @ecryptfs_dir_inode: The eCryptfs directory inode
369  * @ecryptfs_dentry: The eCryptfs dentry that we are looking up
370  * @ecryptfs_nd: nameidata; may be NULL
371  *
372  * Find a file on disk. If the file does not exist, then we'll add it to the
373  * dentry cache and continue on to read it from the disk.
374  */
375 static struct dentry *ecryptfs_lookup(struct inode *ecryptfs_dir_inode,
376                                       struct dentry *ecryptfs_dentry,
377                                       struct nameidata *ecryptfs_nd)
378 {
379         char *encrypted_and_encoded_name = NULL;
380         size_t encrypted_and_encoded_name_size;
381         struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL;
382         struct dentry *lower_dir_dentry, *lower_dentry;
383         int rc = 0;
384
385         if ((ecryptfs_dentry->d_name.len == 1
386              && !strcmp(ecryptfs_dentry->d_name.name, "."))
387             || (ecryptfs_dentry->d_name.len == 2
388                 && !strcmp(ecryptfs_dentry->d_name.name, ".."))) {
389                 goto out_d_drop;
390         }
391         lower_dir_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry->d_parent);
392         mutex_lock(&lower_dir_dentry->d_inode->i_mutex);
393         lower_dentry = lookup_one_len(ecryptfs_dentry->d_name.name,
394                                       lower_dir_dentry,
395                                       ecryptfs_dentry->d_name.len);
396         mutex_unlock(&lower_dir_dentry->d_inode->i_mutex);
397         if (IS_ERR(lower_dentry)) {
398                 rc = PTR_ERR(lower_dentry);
399                 ecryptfs_printk(KERN_DEBUG, "%s: lookup_one_len() returned "
400                                 "[%d] on lower_dentry = [%s]\n", __func__, rc,
401                                 encrypted_and_encoded_name);
402                 goto out_d_drop;
403         }
404         if (lower_dentry->d_inode)
405                 goto interpose;
406         mount_crypt_stat = &ecryptfs_superblock_to_private(
407                                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
408         if (!(mount_crypt_stat
409             && (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)))
410                 goto interpose;
411         dput(lower_dentry);
412         rc = ecryptfs_encrypt_and_encode_filename(
413                 &encrypted_and_encoded_name, &encrypted_and_encoded_name_size,
414                 NULL, mount_crypt_stat, ecryptfs_dentry->d_name.name,
415                 ecryptfs_dentry->d_name.len);
416         if (rc) {
417                 printk(KERN_ERR "%s: Error attempting to encrypt and encode "
418                        "filename; rc = [%d]\n", __func__, rc);
419                 goto out_d_drop;
420         }
421         mutex_lock(&lower_dir_dentry->d_inode->i_mutex);
422         lower_dentry = lookup_one_len(encrypted_and_encoded_name,
423                                       lower_dir_dentry,
424                                       encrypted_and_encoded_name_size);
425         mutex_unlock(&lower_dir_dentry->d_inode->i_mutex);
426         if (IS_ERR(lower_dentry)) {
427                 rc = PTR_ERR(lower_dentry);
428                 ecryptfs_printk(KERN_DEBUG, "%s: lookup_one_len() returned "
429                                 "[%d] on lower_dentry = [%s]\n", __func__, rc,
430                                 encrypted_and_encoded_name);
431                 goto out_d_drop;
432         }
433 interpose:
434         rc = ecryptfs_lookup_interpose(ecryptfs_dentry, lower_dentry,
435                                        ecryptfs_dir_inode);
436         goto out;
437 out_d_drop:
438         d_drop(ecryptfs_dentry);
439 out:
440         kfree(encrypted_and_encoded_name);
441         return ERR_PTR(rc);
442 }
443
444 static int ecryptfs_link(struct dentry *old_dentry, struct inode *dir,
445                          struct dentry *new_dentry)
446 {
447         struct dentry *lower_old_dentry;
448         struct dentry *lower_new_dentry;
449         struct dentry *lower_dir_dentry;
450         u64 file_size_save;
451         int rc;
452
453         file_size_save = i_size_read(old_dentry->d_inode);
454         lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
455         lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
456         dget(lower_old_dentry);
457         dget(lower_new_dentry);
458         lower_dir_dentry = lock_parent(lower_new_dentry);
459         rc = vfs_link(lower_old_dentry, lower_dir_dentry->d_inode,
460                       lower_new_dentry);
461         if (rc || !lower_new_dentry->d_inode)
462                 goto out_lock;
463         rc = ecryptfs_interpose(lower_new_dentry, new_dentry, dir->i_sb);
464         if (rc)
465                 goto out_lock;
466         fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
467         fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
468         set_nlink(old_dentry->d_inode,
469                   ecryptfs_inode_to_lower(old_dentry->d_inode)->i_nlink);
470         i_size_write(new_dentry->d_inode, file_size_save);
471 out_lock:
472         unlock_dir(lower_dir_dentry);
473         dput(lower_new_dentry);
474         dput(lower_old_dentry);
475         return rc;
476 }
477
478 static int ecryptfs_unlink(struct inode *dir, struct dentry *dentry)
479 {
480         int rc = 0;
481         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
482         struct inode *lower_dir_inode = ecryptfs_inode_to_lower(dir);
483         struct dentry *lower_dir_dentry;
484
485         dget(lower_dentry);
486         lower_dir_dentry = lock_parent(lower_dentry);
487         rc = vfs_unlink(lower_dir_inode, lower_dentry);
488         if (rc) {
489                 printk(KERN_ERR "Error in vfs_unlink; rc = [%d]\n", rc);
490                 goto out_unlock;
491         }
492         fsstack_copy_attr_times(dir, lower_dir_inode);
493         set_nlink(dentry->d_inode,
494                   ecryptfs_inode_to_lower(dentry->d_inode)->i_nlink);
495         dentry->d_inode->i_ctime = dir->i_ctime;
496         d_drop(dentry);
497 out_unlock:
498         unlock_dir(lower_dir_dentry);
499         dput(lower_dentry);
500         return rc;
501 }
502
503 static int ecryptfs_symlink(struct inode *dir, struct dentry *dentry,
504                             const char *symname)
505 {
506         int rc;
507         struct dentry *lower_dentry;
508         struct dentry *lower_dir_dentry;
509         char *encoded_symname;
510         size_t encoded_symlen;
511         struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL;
512
513         lower_dentry = ecryptfs_dentry_to_lower(dentry);
514         dget(lower_dentry);
515         lower_dir_dentry = lock_parent(lower_dentry);
516         mount_crypt_stat = &ecryptfs_superblock_to_private(
517                 dir->i_sb)->mount_crypt_stat;
518         rc = ecryptfs_encrypt_and_encode_filename(&encoded_symname,
519                                                   &encoded_symlen,
520                                                   NULL,
521                                                   mount_crypt_stat, symname,
522                                                   strlen(symname));
523         if (rc)
524                 goto out_lock;
525         rc = vfs_symlink(lower_dir_dentry->d_inode, lower_dentry,
526                          encoded_symname);
527         kfree(encoded_symname);
528         if (rc || !lower_dentry->d_inode)
529                 goto out_lock;
530         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
531         if (rc)
532                 goto out_lock;
533         fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
534         fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
535 out_lock:
536         unlock_dir(lower_dir_dentry);
537         dput(lower_dentry);
538         if (!dentry->d_inode)
539                 d_drop(dentry);
540         return rc;
541 }
542
543 static int ecryptfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
544 {
545         int rc;
546         struct dentry *lower_dentry;
547         struct dentry *lower_dir_dentry;
548
549         lower_dentry = ecryptfs_dentry_to_lower(dentry);
550         lower_dir_dentry = lock_parent(lower_dentry);
551         rc = vfs_mkdir(lower_dir_dentry->d_inode, lower_dentry, mode);
552         if (rc || !lower_dentry->d_inode)
553                 goto out;
554         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
555         if (rc)
556                 goto out;
557         fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
558         fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
559         set_nlink(dir, lower_dir_dentry->d_inode->i_nlink);
560 out:
561         unlock_dir(lower_dir_dentry);
562         if (!dentry->d_inode)
563                 d_drop(dentry);
564         return rc;
565 }
566
567 static int ecryptfs_rmdir(struct inode *dir, struct dentry *dentry)
568 {
569         struct dentry *lower_dentry;
570         struct dentry *lower_dir_dentry;
571         int rc;
572
573         lower_dentry = ecryptfs_dentry_to_lower(dentry);
574         dget(dentry);
575         lower_dir_dentry = lock_parent(lower_dentry);
576         dget(lower_dentry);
577         rc = vfs_rmdir(lower_dir_dentry->d_inode, lower_dentry);
578         dput(lower_dentry);
579         if (!rc && dentry->d_inode)
580                 clear_nlink(dentry->d_inode);
581         fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
582         set_nlink(dir, lower_dir_dentry->d_inode->i_nlink);
583         unlock_dir(lower_dir_dentry);
584         if (!rc)
585                 d_drop(dentry);
586         dput(dentry);
587         return rc;
588 }
589
590 static int
591 ecryptfs_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
592 {
593         int rc;
594         struct dentry *lower_dentry;
595         struct dentry *lower_dir_dentry;
596
597         lower_dentry = ecryptfs_dentry_to_lower(dentry);
598         lower_dir_dentry = lock_parent(lower_dentry);
599         rc = vfs_mknod(lower_dir_dentry->d_inode, lower_dentry, mode, dev);
600         if (rc || !lower_dentry->d_inode)
601                 goto out;
602         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
603         if (rc)
604                 goto out;
605         fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
606         fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
607 out:
608         unlock_dir(lower_dir_dentry);
609         if (!dentry->d_inode)
610                 d_drop(dentry);
611         return rc;
612 }
613
614 static int
615 ecryptfs_rename(struct inode *old_dir, struct dentry *old_dentry,
616                 struct inode *new_dir, struct dentry *new_dentry)
617 {
618         int rc;
619         struct dentry *lower_old_dentry;
620         struct dentry *lower_new_dentry;
621         struct dentry *lower_old_dir_dentry;
622         struct dentry *lower_new_dir_dentry;
623         struct dentry *trap = NULL;
624
625         lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
626         lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
627         dget(lower_old_dentry);
628         dget(lower_new_dentry);
629         lower_old_dir_dentry = dget_parent(lower_old_dentry);
630         lower_new_dir_dentry = dget_parent(lower_new_dentry);
631         trap = lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
632         /* source should not be ancestor of target */
633         if (trap == lower_old_dentry) {
634                 rc = -EINVAL;
635                 goto out_lock;
636         }
637         /* target should not be ancestor of source */
638         if (trap == lower_new_dentry) {
639                 rc = -ENOTEMPTY;
640                 goto out_lock;
641         }
642         rc = vfs_rename(lower_old_dir_dentry->d_inode, lower_old_dentry,
643                         lower_new_dir_dentry->d_inode, lower_new_dentry);
644         if (rc)
645                 goto out_lock;
646         fsstack_copy_attr_all(new_dir, lower_new_dir_dentry->d_inode);
647         if (new_dir != old_dir)
648                 fsstack_copy_attr_all(old_dir, lower_old_dir_dentry->d_inode);
649 out_lock:
650         unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
651         dput(lower_new_dir_dentry);
652         dput(lower_old_dir_dentry);
653         dput(lower_new_dentry);
654         dput(lower_old_dentry);
655         return rc;
656 }
657
658 static int ecryptfs_readlink_lower(struct dentry *dentry, char **buf,
659                                    size_t *bufsiz)
660 {
661         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
662         char *lower_buf;
663         mm_segment_t old_fs;
664         int rc;
665
666         lower_buf = kmalloc(PATH_MAX, GFP_KERNEL);
667         if (!lower_buf) {
668                 rc = -ENOMEM;
669                 goto out;
670         }
671         old_fs = get_fs();
672         set_fs(get_ds());
673         rc = lower_dentry->d_inode->i_op->readlink(lower_dentry,
674                                                    (char __user *)lower_buf,
675                                                    PATH_MAX);
676         set_fs(old_fs);
677         if (rc < 0)
678                 goto out;
679         rc = ecryptfs_decode_and_decrypt_filename(buf, bufsiz, dentry,
680                                                   lower_buf, rc);
681 out:
682         kfree(lower_buf);
683         return rc;
684 }
685
686 static void *ecryptfs_follow_link(struct dentry *dentry, struct nameidata *nd)
687 {
688         char *buf;
689         size_t len = PATH_MAX;
690         int rc;
691
692         rc = ecryptfs_readlink_lower(dentry, &buf, &len);
693         if (rc)
694                 goto out;
695         fsstack_copy_attr_atime(dentry->d_inode,
696                                 ecryptfs_dentry_to_lower(dentry)->d_inode);
697         buf[len] = '\0';
698 out:
699         nd_set_link(nd, buf);
700         return NULL;
701 }
702
703 static void
704 ecryptfs_put_link(struct dentry *dentry, struct nameidata *nd, void *ptr)
705 {
706         char *buf = nd_get_link(nd);
707         if (!IS_ERR(buf)) {
708                 /* Free the char* */
709                 kfree(buf);
710         }
711 }
712
713 /**
714  * upper_size_to_lower_size
715  * @crypt_stat: Crypt_stat associated with file
716  * @upper_size: Size of the upper file
717  *
718  * Calculate the required size of the lower file based on the
719  * specified size of the upper file. This calculation is based on the
720  * number of headers in the underlying file and the extent size.
721  *
722  * Returns Calculated size of the lower file.
723  */
724 static loff_t
725 upper_size_to_lower_size(struct ecryptfs_crypt_stat *crypt_stat,
726                          loff_t upper_size)
727 {
728         loff_t lower_size;
729
730         lower_size = ecryptfs_lower_header_size(crypt_stat);
731         if (upper_size != 0) {
732                 loff_t num_extents;
733
734                 num_extents = upper_size >> crypt_stat->extent_shift;
735                 if (upper_size & ~crypt_stat->extent_mask)
736                         num_extents++;
737                 lower_size += (num_extents * crypt_stat->extent_size);
738         }
739         return lower_size;
740 }
741
742 /**
743  * truncate_upper
744  * @dentry: The ecryptfs layer dentry
745  * @ia: Address of the ecryptfs inode's attributes
746  * @lower_ia: Address of the lower inode's attributes
747  *
748  * Function to handle truncations modifying the size of the file. Note
749  * that the file sizes are interpolated. When expanding, we are simply
750  * writing strings of 0's out. When truncating, we truncate the upper
751  * inode and update the lower_ia according to the page index
752  * interpolations. If ATTR_SIZE is set in lower_ia->ia_valid upon return,
753  * the caller must use lower_ia in a call to notify_change() to perform
754  * the truncation of the lower inode.
755  *
756  * Returns zero on success; non-zero otherwise
757  */
758 static int truncate_upper(struct dentry *dentry, struct iattr *ia,
759                           struct iattr *lower_ia)
760 {
761         int rc = 0;
762         struct inode *inode = dentry->d_inode;
763         struct ecryptfs_crypt_stat *crypt_stat;
764         loff_t i_size = i_size_read(inode);
765         loff_t lower_size_before_truncate;
766         loff_t lower_size_after_truncate;
767
768         if (unlikely((ia->ia_size == i_size))) {
769                 lower_ia->ia_valid &= ~ATTR_SIZE;
770                 return 0;
771         }
772         rc = ecryptfs_get_lower_file(dentry, inode);
773         if (rc)
774                 return rc;
775         crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
776         /* Switch on growing or shrinking file */
777         if (ia->ia_size > i_size) {
778                 char zero[] = { 0x00 };
779
780                 lower_ia->ia_valid &= ~ATTR_SIZE;
781                 /* Write a single 0 at the last position of the file;
782                  * this triggers code that will fill in 0's throughout
783                  * the intermediate portion of the previous end of the
784                  * file and the new and of the file */
785                 rc = ecryptfs_write(inode, zero,
786                                     (ia->ia_size - 1), 1);
787         } else { /* ia->ia_size < i_size_read(inode) */
788                 /* We're chopping off all the pages down to the page
789                  * in which ia->ia_size is located. Fill in the end of
790                  * that page from (ia->ia_size & ~PAGE_CACHE_MASK) to
791                  * PAGE_CACHE_SIZE with zeros. */
792                 size_t num_zeros = (PAGE_CACHE_SIZE
793                                     - (ia->ia_size & ~PAGE_CACHE_MASK));
794
795                 if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
796                         truncate_setsize(inode, ia->ia_size);
797                         lower_ia->ia_size = ia->ia_size;
798                         lower_ia->ia_valid |= ATTR_SIZE;
799                         goto out;
800                 }
801                 if (num_zeros) {
802                         char *zeros_virt;
803
804                         zeros_virt = kzalloc(num_zeros, GFP_KERNEL);
805                         if (!zeros_virt) {
806                                 rc = -ENOMEM;
807                                 goto out;
808                         }
809                         rc = ecryptfs_write(inode, zeros_virt,
810                                             ia->ia_size, num_zeros);
811                         kfree(zeros_virt);
812                         if (rc) {
813                                 printk(KERN_ERR "Error attempting to zero out "
814                                        "the remainder of the end page on "
815                                        "reducing truncate; rc = [%d]\n", rc);
816                                 goto out;
817                         }
818                 }
819                 truncate_setsize(inode, ia->ia_size);
820                 rc = ecryptfs_write_inode_size_to_metadata(inode);
821                 if (rc) {
822                         printk(KERN_ERR "Problem with "
823                                "ecryptfs_write_inode_size_to_metadata; "
824                                "rc = [%d]\n", rc);
825                         goto out;
826                 }
827                 /* We are reducing the size of the ecryptfs file, and need to
828                  * know if we need to reduce the size of the lower file. */
829                 lower_size_before_truncate =
830                     upper_size_to_lower_size(crypt_stat, i_size);
831                 lower_size_after_truncate =
832                     upper_size_to_lower_size(crypt_stat, ia->ia_size);
833                 if (lower_size_after_truncate < lower_size_before_truncate) {
834                         lower_ia->ia_size = lower_size_after_truncate;
835                         lower_ia->ia_valid |= ATTR_SIZE;
836                 } else
837                         lower_ia->ia_valid &= ~ATTR_SIZE;
838         }
839 out:
840         ecryptfs_put_lower_file(inode);
841         return rc;
842 }
843
844 static int ecryptfs_inode_newsize_ok(struct inode *inode, loff_t offset)
845 {
846         struct ecryptfs_crypt_stat *crypt_stat;
847         loff_t lower_oldsize, lower_newsize;
848
849         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
850         lower_oldsize = upper_size_to_lower_size(crypt_stat,
851                                                  i_size_read(inode));
852         lower_newsize = upper_size_to_lower_size(crypt_stat, offset);
853         if (lower_newsize > lower_oldsize) {
854                 /*
855                  * The eCryptfs inode and the new *lower* size are mixed here
856                  * because we may not have the lower i_mutex held and/or it may
857                  * not be appropriate to call inode_newsize_ok() with inodes
858                  * from other filesystems.
859                  */
860                 return inode_newsize_ok(inode, lower_newsize);
861         }
862
863         return 0;
864 }
865
866 /**
867  * ecryptfs_truncate
868  * @dentry: The ecryptfs layer dentry
869  * @new_length: The length to expand the file to
870  *
871  * Simple function that handles the truncation of an eCryptfs inode and
872  * its corresponding lower inode.
873  *
874  * Returns zero on success; non-zero otherwise
875  */
876 int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
877 {
878         struct iattr ia = { .ia_valid = ATTR_SIZE, .ia_size = new_length };
879         struct iattr lower_ia = { .ia_valid = 0 };
880         int rc;
881
882         rc = ecryptfs_inode_newsize_ok(dentry->d_inode, new_length);
883         if (rc)
884                 return rc;
885
886         rc = truncate_upper(dentry, &ia, &lower_ia);
887         if (!rc && lower_ia.ia_valid & ATTR_SIZE) {
888                 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
889
890                 mutex_lock(&lower_dentry->d_inode->i_mutex);
891                 rc = notify_change(lower_dentry, &lower_ia);
892                 mutex_unlock(&lower_dentry->d_inode->i_mutex);
893         }
894         return rc;
895 }
896
897 static int
898 ecryptfs_permission(struct inode *inode, int mask)
899 {
900         return inode_permission(ecryptfs_inode_to_lower(inode), mask);
901 }
902
903 /**
904  * ecryptfs_setattr
905  * @dentry: dentry handle to the inode to modify
906  * @ia: Structure with flags of what to change and values
907  *
908  * Updates the metadata of an inode. If the update is to the size
909  * i.e. truncation, then ecryptfs_truncate will handle the size modification
910  * of both the ecryptfs inode and the lower inode.
911  *
912  * All other metadata changes will be passed right to the lower filesystem,
913  * and we will just update our inode to look like the lower.
914  */
915 static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
916 {
917         int rc = 0;
918         struct dentry *lower_dentry;
919         struct iattr lower_ia;
920         struct inode *inode;
921         struct inode *lower_inode;
922         struct ecryptfs_crypt_stat *crypt_stat;
923
924         crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
925         if (!(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED))
926                 ecryptfs_init_crypt_stat(crypt_stat);
927         inode = dentry->d_inode;
928         lower_inode = ecryptfs_inode_to_lower(inode);
929         lower_dentry = ecryptfs_dentry_to_lower(dentry);
930         mutex_lock(&crypt_stat->cs_mutex);
931         if (S_ISDIR(dentry->d_inode->i_mode))
932                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
933         else if (S_ISREG(dentry->d_inode->i_mode)
934                  && (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
935                      || !(crypt_stat->flags & ECRYPTFS_KEY_VALID))) {
936                 struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
937
938                 mount_crypt_stat = &ecryptfs_superblock_to_private(
939                         dentry->d_sb)->mount_crypt_stat;
940                 rc = ecryptfs_get_lower_file(dentry, inode);
941                 if (rc) {
942                         mutex_unlock(&crypt_stat->cs_mutex);
943                         goto out;
944                 }
945                 rc = ecryptfs_read_metadata(dentry);
946                 ecryptfs_put_lower_file(inode);
947                 if (rc) {
948                         if (!(mount_crypt_stat->flags
949                               & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
950                                 rc = -EIO;
951                                 printk(KERN_WARNING "Either the lower file "
952                                        "is not in a valid eCryptfs format, "
953                                        "or the key could not be retrieved. "
954                                        "Plaintext passthrough mode is not "
955                                        "enabled; returning -EIO\n");
956                                 mutex_unlock(&crypt_stat->cs_mutex);
957                                 goto out;
958                         }
959                         rc = 0;
960                         crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
961                                                | ECRYPTFS_ENCRYPTED);
962                 }
963         }
964         mutex_unlock(&crypt_stat->cs_mutex);
965
966         rc = inode_change_ok(inode, ia);
967         if (rc)
968                 goto out;
969         if (ia->ia_valid & ATTR_SIZE) {
970                 rc = ecryptfs_inode_newsize_ok(inode, ia->ia_size);
971                 if (rc)
972                         goto out;
973         }
974
975         if (S_ISREG(inode->i_mode)) {
976                 rc = filemap_write_and_wait(inode->i_mapping);
977                 if (rc)
978                         goto out;
979                 fsstack_copy_attr_all(inode, lower_inode);
980         }
981         memcpy(&lower_ia, ia, sizeof(lower_ia));
982         if (ia->ia_valid & ATTR_FILE)
983                 lower_ia.ia_file = ecryptfs_file_to_lower(ia->ia_file);
984         if (ia->ia_valid & ATTR_SIZE) {
985                 rc = truncate_upper(dentry, ia, &lower_ia);
986                 if (rc < 0)
987                         goto out;
988         }
989
990         /*
991          * mode change is for clearing setuid/setgid bits. Allow lower fs
992          * to interpret this in its own way.
993          */
994         if (lower_ia.ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
995                 lower_ia.ia_valid &= ~ATTR_MODE;
996
997         mutex_lock(&lower_dentry->d_inode->i_mutex);
998         rc = notify_change(lower_dentry, &lower_ia);
999         mutex_unlock(&lower_dentry->d_inode->i_mutex);
1000 out:
1001         fsstack_copy_attr_all(inode, lower_inode);
1002         return rc;
1003 }
1004
1005 int ecryptfs_getattr_link(struct vfsmount *mnt, struct dentry *dentry,
1006                           struct kstat *stat)
1007 {
1008         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
1009         int rc = 0;
1010
1011         mount_crypt_stat = &ecryptfs_superblock_to_private(
1012                                                 dentry->d_sb)->mount_crypt_stat;
1013         generic_fillattr(dentry->d_inode, stat);
1014         if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
1015                 char *target;
1016                 size_t targetsiz;
1017
1018                 rc = ecryptfs_readlink_lower(dentry, &target, &targetsiz);
1019                 if (!rc) {
1020                         kfree(target);
1021                         stat->size = targetsiz;
1022                 }
1023         }
1024         return rc;
1025 }
1026
1027 int ecryptfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
1028                      struct kstat *stat)
1029 {
1030         struct kstat lower_stat;
1031         int rc;
1032
1033         rc = vfs_getattr(ecryptfs_dentry_to_lower_mnt(dentry),
1034                          ecryptfs_dentry_to_lower(dentry), &lower_stat);
1035         if (!rc) {
1036                 fsstack_copy_attr_all(dentry->d_inode,
1037                                       ecryptfs_inode_to_lower(dentry->d_inode));
1038                 generic_fillattr(dentry->d_inode, stat);
1039                 stat->blocks = lower_stat.blocks;
1040         }
1041         return rc;
1042 }
1043
1044 int
1045 ecryptfs_setxattr(struct dentry *dentry, const char *name, const void *value,
1046                   size_t size, int flags)
1047 {
1048         int rc = 0;
1049         struct dentry *lower_dentry;
1050
1051         lower_dentry = ecryptfs_dentry_to_lower(dentry);
1052         if (!lower_dentry->d_inode->i_op->setxattr) {
1053                 rc = -EOPNOTSUPP;
1054                 goto out;
1055         }
1056
1057         rc = vfs_setxattr(lower_dentry, name, value, size, flags);
1058         if (!rc)
1059                 fsstack_copy_attr_all(dentry->d_inode, lower_dentry->d_inode);
1060 out:
1061         return rc;
1062 }
1063
1064 ssize_t
1065 ecryptfs_getxattr_lower(struct dentry *lower_dentry, const char *name,
1066                         void *value, size_t size)
1067 {
1068         int rc = 0;
1069
1070         if (!lower_dentry->d_inode->i_op->getxattr) {
1071                 rc = -EOPNOTSUPP;
1072                 goto out;
1073         }
1074         mutex_lock(&lower_dentry->d_inode->i_mutex);
1075         rc = lower_dentry->d_inode->i_op->getxattr(lower_dentry, name, value,
1076                                                    size);
1077         mutex_unlock(&lower_dentry->d_inode->i_mutex);
1078 out:
1079         return rc;
1080 }
1081
1082 static ssize_t
1083 ecryptfs_getxattr(struct dentry *dentry, const char *name, void *value,
1084                   size_t size)
1085 {
1086         return ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry), name,
1087                                        value, size);
1088 }
1089
1090 static ssize_t
1091 ecryptfs_listxattr(struct dentry *dentry, char *list, size_t size)
1092 {
1093         int rc = 0;
1094         struct dentry *lower_dentry;
1095
1096         lower_dentry = ecryptfs_dentry_to_lower(dentry);
1097         if (!lower_dentry->d_inode->i_op->listxattr) {
1098                 rc = -EOPNOTSUPP;
1099                 goto out;
1100         }
1101         mutex_lock(&lower_dentry->d_inode->i_mutex);
1102         rc = lower_dentry->d_inode->i_op->listxattr(lower_dentry, list, size);
1103         mutex_unlock(&lower_dentry->d_inode->i_mutex);
1104 out:
1105         return rc;
1106 }
1107
1108 static int ecryptfs_removexattr(struct dentry *dentry, const char *name)
1109 {
1110         int rc = 0;
1111         struct dentry *lower_dentry;
1112
1113         lower_dentry = ecryptfs_dentry_to_lower(dentry);
1114         if (!lower_dentry->d_inode->i_op->removexattr) {
1115                 rc = -EOPNOTSUPP;
1116                 goto out;
1117         }
1118         mutex_lock(&lower_dentry->d_inode->i_mutex);
1119         rc = lower_dentry->d_inode->i_op->removexattr(lower_dentry, name);
1120         mutex_unlock(&lower_dentry->d_inode->i_mutex);
1121 out:
1122         return rc;
1123 }
1124
1125 const struct inode_operations ecryptfs_symlink_iops = {
1126         .readlink = generic_readlink,
1127         .follow_link = ecryptfs_follow_link,
1128         .put_link = ecryptfs_put_link,
1129         .permission = ecryptfs_permission,
1130         .setattr = ecryptfs_setattr,
1131         .getattr = ecryptfs_getattr_link,
1132         .setxattr = ecryptfs_setxattr,
1133         .getxattr = ecryptfs_getxattr,
1134         .listxattr = ecryptfs_listxattr,
1135         .removexattr = ecryptfs_removexattr
1136 };
1137
1138 const struct inode_operations ecryptfs_dir_iops = {
1139         .create = ecryptfs_create,
1140         .lookup = ecryptfs_lookup,
1141         .link = ecryptfs_link,
1142         .unlink = ecryptfs_unlink,
1143         .symlink = ecryptfs_symlink,
1144         .mkdir = ecryptfs_mkdir,
1145         .rmdir = ecryptfs_rmdir,
1146         .mknod = ecryptfs_mknod,
1147         .rename = ecryptfs_rename,
1148         .permission = ecryptfs_permission,
1149         .setattr = ecryptfs_setattr,
1150         .setxattr = ecryptfs_setxattr,
1151         .getxattr = ecryptfs_getxattr,
1152         .listxattr = ecryptfs_listxattr,
1153         .removexattr = ecryptfs_removexattr
1154 };
1155
1156 const struct inode_operations ecryptfs_main_iops = {
1157         .permission = ecryptfs_permission,
1158         .setattr = ecryptfs_setattr,
1159         .getattr = ecryptfs_getattr,
1160         .setxattr = ecryptfs_setxattr,
1161         .getxattr = ecryptfs_getxattr,
1162         .listxattr = ecryptfs_listxattr,
1163         .removexattr = ecryptfs_removexattr
1164 };