eCryptfs: Add getattr function
[linux-2.6.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 <asm/unaligned.h>
35 #include "ecryptfs_kernel.h"
36
37 static struct dentry *lock_parent(struct dentry *dentry)
38 {
39         struct dentry *dir;
40
41         dir = dget_parent(dentry);
42         mutex_lock_nested(&(dir->d_inode->i_mutex), I_MUTEX_PARENT);
43         return dir;
44 }
45
46 static void unlock_dir(struct dentry *dir)
47 {
48         mutex_unlock(&dir->d_inode->i_mutex);
49         dput(dir);
50 }
51
52 /**
53  * ecryptfs_create_underlying_file
54  * @lower_dir_inode: inode of the parent in the lower fs of the new file
55  * @dentry: New file's dentry
56  * @mode: The mode of the new file
57  * @nd: nameidata of ecryptfs' parent's dentry & vfsmount
58  *
59  * Creates the file in the lower file system.
60  *
61  * Returns zero on success; non-zero on error condition
62  */
63 static int
64 ecryptfs_create_underlying_file(struct inode *lower_dir_inode,
65                                 struct dentry *dentry, int mode,
66                                 struct nameidata *nd)
67 {
68         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
69         struct vfsmount *lower_mnt = ecryptfs_dentry_to_lower_mnt(dentry);
70         struct dentry *dentry_save;
71         struct vfsmount *vfsmount_save;
72         int rc;
73
74         dentry_save = nd->path.dentry;
75         vfsmount_save = nd->path.mnt;
76         nd->path.dentry = lower_dentry;
77         nd->path.mnt = lower_mnt;
78         rc = vfs_create(lower_dir_inode, lower_dentry, mode, nd);
79         nd->path.dentry = dentry_save;
80         nd->path.mnt = vfsmount_save;
81         return rc;
82 }
83
84 /**
85  * ecryptfs_do_create
86  * @directory_inode: inode of the new file's dentry's parent in ecryptfs
87  * @ecryptfs_dentry: New file's dentry in ecryptfs
88  * @mode: The mode of the new file
89  * @nd: nameidata of ecryptfs' parent's dentry & vfsmount
90  *
91  * Creates the underlying file and the eCryptfs inode which will link to
92  * it. It will also update the eCryptfs directory inode to mimic the
93  * stat of the lower directory inode.
94  *
95  * Returns zero on success; non-zero on error condition
96  */
97 static int
98 ecryptfs_do_create(struct inode *directory_inode,
99                    struct dentry *ecryptfs_dentry, int mode,
100                    struct nameidata *nd)
101 {
102         int rc;
103         struct dentry *lower_dentry;
104         struct dentry *lower_dir_dentry;
105
106         lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
107         lower_dir_dentry = lock_parent(lower_dentry);
108         if (IS_ERR(lower_dir_dentry)) {
109                 ecryptfs_printk(KERN_ERR, "Error locking directory of "
110                                 "dentry\n");
111                 rc = PTR_ERR(lower_dir_dentry);
112                 goto out;
113         }
114         rc = ecryptfs_create_underlying_file(lower_dir_dentry->d_inode,
115                                              ecryptfs_dentry, mode, nd);
116         if (rc) {
117                 printk(KERN_ERR "%s: Failure to create dentry in lower fs; "
118                        "rc = [%d]\n", __func__, rc);
119                 goto out_lock;
120         }
121         rc = ecryptfs_interpose(lower_dentry, ecryptfs_dentry,
122                                 directory_inode->i_sb, 0);
123         if (rc) {
124                 ecryptfs_printk(KERN_ERR, "Failure in ecryptfs_interpose\n");
125                 goto out_lock;
126         }
127         fsstack_copy_attr_times(directory_inode, lower_dir_dentry->d_inode);
128         fsstack_copy_inode_size(directory_inode, lower_dir_dentry->d_inode);
129 out_lock:
130         unlock_dir(lower_dir_dentry);
131 out:
132         return rc;
133 }
134
135 /**
136  * grow_file
137  * @ecryptfs_dentry: the eCryptfs dentry
138  *
139  * This is the code which will grow the file to its correct size.
140  */
141 static int grow_file(struct dentry *ecryptfs_dentry)
142 {
143         struct inode *ecryptfs_inode = ecryptfs_dentry->d_inode;
144         struct file fake_file;
145         struct ecryptfs_file_info tmp_file_info;
146         char zero_virt[] = { 0x00 };
147         int rc = 0;
148
149         memset(&fake_file, 0, sizeof(fake_file));
150         fake_file.f_path.dentry = ecryptfs_dentry;
151         memset(&tmp_file_info, 0, sizeof(tmp_file_info));
152         ecryptfs_set_file_private(&fake_file, &tmp_file_info);
153         ecryptfs_set_file_lower(
154                 &fake_file,
155                 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file);
156         rc = ecryptfs_write(&fake_file, zero_virt, 0, 1);
157         i_size_write(ecryptfs_inode, 0);
158         rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode);
159         ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat.flags |=
160                 ECRYPTFS_NEW_FILE;
161         return rc;
162 }
163
164 /**
165  * ecryptfs_initialize_file
166  *
167  * Cause the file to be changed from a basic empty file to an ecryptfs
168  * file with a header and first data page.
169  *
170  * Returns zero on success
171  */
172 static int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry)
173 {
174         struct ecryptfs_crypt_stat *crypt_stat =
175                 &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
176         int rc = 0;
177
178         if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
179                 ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
180                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
181                 goto out;
182         }
183         crypt_stat->flags |= ECRYPTFS_NEW_FILE;
184         ecryptfs_printk(KERN_DEBUG, "Initializing crypto context\n");
185         rc = ecryptfs_new_file_context(ecryptfs_dentry);
186         if (rc) {
187                 ecryptfs_printk(KERN_ERR, "Error creating new file "
188                                 "context; rc = [%d]\n", rc);
189                 goto out;
190         }
191         if (!ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->lower_file) {
192                 rc = ecryptfs_init_persistent_file(ecryptfs_dentry);
193                 if (rc) {
194                         printk(KERN_ERR "%s: Error attempting to initialize "
195                                "the persistent file for the dentry with name "
196                                "[%s]; rc = [%d]\n", __func__,
197                                ecryptfs_dentry->d_name.name, rc);
198                         goto out;
199                 }
200         }
201         rc = ecryptfs_write_metadata(ecryptfs_dentry);
202         if (rc) {
203                 printk(KERN_ERR "Error writing headers; rc = [%d]\n", rc);
204                 goto out;
205         }
206         rc = grow_file(ecryptfs_dentry);
207         if (rc)
208                 printk(KERN_ERR "Error growing file; rc = [%d]\n", rc);
209 out:
210         return rc;
211 }
212
213 /**
214  * ecryptfs_create
215  * @dir: The inode of the directory in which to create the file.
216  * @dentry: The eCryptfs dentry
217  * @mode: The mode of the new file.
218  * @nd: nameidata
219  *
220  * Creates a new file.
221  *
222  * Returns zero on success; non-zero on error condition
223  */
224 static int
225 ecryptfs_create(struct inode *directory_inode, struct dentry *ecryptfs_dentry,
226                 int mode, struct nameidata *nd)
227 {
228         int rc;
229
230         /* ecryptfs_do_create() calls ecryptfs_interpose() */
231         rc = ecryptfs_do_create(directory_inode, ecryptfs_dentry, mode, nd);
232         if (unlikely(rc)) {
233                 ecryptfs_printk(KERN_WARNING, "Failed to create file in"
234                                 "lower filesystem\n");
235                 goto out;
236         }
237         /* At this point, a file exists on "disk"; we need to make sure
238          * that this on disk file is prepared to be an ecryptfs file */
239         rc = ecryptfs_initialize_file(ecryptfs_dentry);
240 out:
241         return rc;
242 }
243
244 /**
245  * ecryptfs_lookup_and_interpose_lower - Perform a lookup
246  */
247 int ecryptfs_lookup_and_interpose_lower(struct dentry *ecryptfs_dentry,
248                                         struct dentry *lower_dentry,
249                                         struct inode *ecryptfs_dir_inode,
250                                         struct nameidata *ecryptfs_nd)
251 {
252         struct dentry *lower_dir_dentry;
253         struct vfsmount *lower_mnt;
254         struct inode *lower_inode;
255         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
256         struct ecryptfs_crypt_stat *crypt_stat;
257         char *page_virt = NULL;
258         u64 file_size;
259         int rc = 0;
260
261         lower_dir_dentry = lower_dentry->d_parent;
262         lower_mnt = mntget(ecryptfs_dentry_to_lower_mnt(
263                                    ecryptfs_dentry->d_parent));
264         lower_inode = lower_dentry->d_inode;
265         fsstack_copy_attr_atime(ecryptfs_dir_inode, lower_dir_dentry->d_inode);
266         BUG_ON(!atomic_read(&lower_dentry->d_count));
267         ecryptfs_set_dentry_private(ecryptfs_dentry,
268                                     kmem_cache_alloc(ecryptfs_dentry_info_cache,
269                                                      GFP_KERNEL));
270         if (!ecryptfs_dentry_to_private(ecryptfs_dentry)) {
271                 rc = -ENOMEM;
272                 printk(KERN_ERR "%s: Out of memory whilst attempting "
273                        "to allocate ecryptfs_dentry_info struct\n",
274                         __func__);
275                 goto out_dput;
276         }
277         ecryptfs_set_dentry_lower(ecryptfs_dentry, lower_dentry);
278         ecryptfs_set_dentry_lower_mnt(ecryptfs_dentry, lower_mnt);
279         if (!lower_dentry->d_inode) {
280                 /* We want to add because we couldn't find in lower */
281                 d_add(ecryptfs_dentry, NULL);
282                 goto out;
283         }
284         rc = ecryptfs_interpose(lower_dentry, ecryptfs_dentry,
285                                 ecryptfs_dir_inode->i_sb, 1);
286         if (rc) {
287                 printk(KERN_ERR "%s: Error interposing; rc = [%d]\n",
288                        __func__, rc);
289                 goto out;
290         }
291         if (S_ISDIR(lower_inode->i_mode))
292                 goto out;
293         if (S_ISLNK(lower_inode->i_mode))
294                 goto out;
295         if (special_file(lower_inode->i_mode))
296                 goto out;
297         if (!ecryptfs_nd)
298                 goto out;
299         /* Released in this function */
300         page_virt = kmem_cache_zalloc(ecryptfs_header_cache_2, GFP_USER);
301         if (!page_virt) {
302                 printk(KERN_ERR "%s: Cannot kmem_cache_zalloc() a page\n",
303                        __func__);
304                 rc = -ENOMEM;
305                 goto out;
306         }
307         if (!ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->lower_file) {
308                 rc = ecryptfs_init_persistent_file(ecryptfs_dentry);
309                 if (rc) {
310                         printk(KERN_ERR "%s: Error attempting to initialize "
311                                "the persistent file for the dentry with name "
312                                "[%s]; rc = [%d]\n", __func__,
313                                ecryptfs_dentry->d_name.name, rc);
314                         goto out_free_kmem;
315                 }
316         }
317         crypt_stat = &ecryptfs_inode_to_private(
318                                         ecryptfs_dentry->d_inode)->crypt_stat;
319         /* TODO: lock for crypt_stat comparison */
320         if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED))
321                         ecryptfs_set_default_sizes(crypt_stat);
322         rc = ecryptfs_read_and_validate_header_region(page_virt,
323                                                       ecryptfs_dentry->d_inode);
324         if (rc) {
325                 rc = ecryptfs_read_and_validate_xattr_region(page_virt,
326                                                              ecryptfs_dentry);
327                 if (rc) {
328                         rc = 0;
329                         goto out_free_kmem;
330                 }
331                 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
332         }
333         mount_crypt_stat = &ecryptfs_superblock_to_private(
334                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
335         if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
336                 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
337                         file_size = (crypt_stat->num_header_bytes_at_front
338                                      + i_size_read(lower_dentry->d_inode));
339                 else
340                         file_size = i_size_read(lower_dentry->d_inode);
341         } else {
342                 file_size = get_unaligned_be64(page_virt);
343         }
344         i_size_write(ecryptfs_dentry->d_inode, (loff_t)file_size);
345 out_free_kmem:
346         kmem_cache_free(ecryptfs_header_cache_2, page_virt);
347         goto out;
348 out_dput:
349         dput(lower_dentry);
350         d_drop(ecryptfs_dentry);
351 out:
352         return rc;
353 }
354
355 /**
356  * ecryptfs_lookup
357  * @ecryptfs_dir_inode: The eCryptfs directory inode
358  * @ecryptfs_dentry: The eCryptfs dentry that we are looking up
359  * @ecryptfs_nd: nameidata; may be NULL
360  *
361  * Find a file on disk. If the file does not exist, then we'll add it to the
362  * dentry cache and continue on to read it from the disk.
363  */
364 static struct dentry *ecryptfs_lookup(struct inode *ecryptfs_dir_inode,
365                                       struct dentry *ecryptfs_dentry,
366                                       struct nameidata *ecryptfs_nd)
367 {
368         char *encrypted_and_encoded_name = NULL;
369         size_t encrypted_and_encoded_name_size;
370         struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL;
371         struct dentry *lower_dir_dentry, *lower_dentry;
372         int rc = 0;
373
374         ecryptfs_dentry->d_op = &ecryptfs_dops;
375         if ((ecryptfs_dentry->d_name.len == 1
376              && !strcmp(ecryptfs_dentry->d_name.name, "."))
377             || (ecryptfs_dentry->d_name.len == 2
378                 && !strcmp(ecryptfs_dentry->d_name.name, ".."))) {
379                 goto out_d_drop;
380         }
381         lower_dir_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry->d_parent);
382         mutex_lock(&lower_dir_dentry->d_inode->i_mutex);
383         lower_dentry = lookup_one_len(ecryptfs_dentry->d_name.name,
384                                       lower_dir_dentry,
385                                       ecryptfs_dentry->d_name.len);
386         mutex_unlock(&lower_dir_dentry->d_inode->i_mutex);
387         if (IS_ERR(lower_dentry)) {
388                 rc = PTR_ERR(lower_dentry);
389                 printk(KERN_ERR "%s: lookup_one_len() returned [%d] on "
390                        "lower_dentry = [%s]\n", __func__, rc,
391                        ecryptfs_dentry->d_name.name);
392                 goto out_d_drop;
393         }
394         if (lower_dentry->d_inode)
395                 goto lookup_and_interpose;
396         mount_crypt_stat = &ecryptfs_superblock_to_private(
397                                 ecryptfs_dentry->d_sb)->mount_crypt_stat;
398         if (!(mount_crypt_stat
399             && (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)))
400                 goto lookup_and_interpose;
401         dput(lower_dentry);
402         rc = ecryptfs_encrypt_and_encode_filename(
403                 &encrypted_and_encoded_name, &encrypted_and_encoded_name_size,
404                 NULL, mount_crypt_stat, ecryptfs_dentry->d_name.name,
405                 ecryptfs_dentry->d_name.len);
406         if (rc) {
407                 printk(KERN_ERR "%s: Error attempting to encrypt and encode "
408                        "filename; rc = [%d]\n", __func__, rc);
409                 goto out_d_drop;
410         }
411         mutex_lock(&lower_dir_dentry->d_inode->i_mutex);
412         lower_dentry = lookup_one_len(encrypted_and_encoded_name,
413                                       lower_dir_dentry,
414                                       encrypted_and_encoded_name_size - 1);
415         mutex_unlock(&lower_dir_dentry->d_inode->i_mutex);
416         if (IS_ERR(lower_dentry)) {
417                 rc = PTR_ERR(lower_dentry);
418                 printk(KERN_ERR "%s: lookup_one_len() returned [%d] on "
419                        "lower_dentry = [%s]\n", __func__, rc,
420                        encrypted_and_encoded_name);
421                 goto out_d_drop;
422         }
423 lookup_and_interpose:
424         rc = ecryptfs_lookup_and_interpose_lower(ecryptfs_dentry, lower_dentry,
425                                                  ecryptfs_dir_inode,
426                                                  ecryptfs_nd);
427         goto out;
428 out_d_drop:
429         d_drop(ecryptfs_dentry);
430 out:
431         kfree(encrypted_and_encoded_name);
432         return ERR_PTR(rc);
433 }
434
435 static int ecryptfs_link(struct dentry *old_dentry, struct inode *dir,
436                          struct dentry *new_dentry)
437 {
438         struct dentry *lower_old_dentry;
439         struct dentry *lower_new_dentry;
440         struct dentry *lower_dir_dentry;
441         u64 file_size_save;
442         int rc;
443
444         file_size_save = i_size_read(old_dentry->d_inode);
445         lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
446         lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
447         dget(lower_old_dentry);
448         dget(lower_new_dentry);
449         lower_dir_dentry = lock_parent(lower_new_dentry);
450         rc = vfs_link(lower_old_dentry, lower_dir_dentry->d_inode,
451                       lower_new_dentry);
452         if (rc || !lower_new_dentry->d_inode)
453                 goto out_lock;
454         rc = ecryptfs_interpose(lower_new_dentry, new_dentry, dir->i_sb, 0);
455         if (rc)
456                 goto out_lock;
457         fsstack_copy_attr_times(dir, lower_new_dentry->d_inode);
458         fsstack_copy_inode_size(dir, lower_new_dentry->d_inode);
459         old_dentry->d_inode->i_nlink =
460                 ecryptfs_inode_to_lower(old_dentry->d_inode)->i_nlink;
461         i_size_write(new_dentry->d_inode, file_size_save);
462 out_lock:
463         unlock_dir(lower_dir_dentry);
464         dput(lower_new_dentry);
465         dput(lower_old_dentry);
466         d_drop(lower_old_dentry);
467         d_drop(new_dentry);
468         d_drop(old_dentry);
469         return rc;
470 }
471
472 static int ecryptfs_unlink(struct inode *dir, struct dentry *dentry)
473 {
474         int rc = 0;
475         struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
476         struct inode *lower_dir_inode = ecryptfs_inode_to_lower(dir);
477         struct dentry *lower_dir_dentry;
478
479         dget(lower_dentry);
480         lower_dir_dentry = lock_parent(lower_dentry);
481         rc = vfs_unlink(lower_dir_inode, lower_dentry);
482         if (rc) {
483                 printk(KERN_ERR "Error in vfs_unlink; rc = [%d]\n", rc);
484                 goto out_unlock;
485         }
486         fsstack_copy_attr_times(dir, lower_dir_inode);
487         dentry->d_inode->i_nlink =
488                 ecryptfs_inode_to_lower(dentry->d_inode)->i_nlink;
489         dentry->d_inode->i_ctime = dir->i_ctime;
490         d_drop(dentry);
491 out_unlock:
492         unlock_dir(lower_dir_dentry);
493         dput(lower_dentry);
494         return rc;
495 }
496
497 static int ecryptfs_symlink(struct inode *dir, struct dentry *dentry,
498                             const char *symname)
499 {
500         int rc;
501         struct dentry *lower_dentry;
502         struct dentry *lower_dir_dentry;
503         char *encoded_symname;
504         size_t encoded_symlen;
505         struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL;
506
507         lower_dentry = ecryptfs_dentry_to_lower(dentry);
508         dget(lower_dentry);
509         lower_dir_dentry = lock_parent(lower_dentry);
510         mount_crypt_stat = &ecryptfs_superblock_to_private(
511                 dir->i_sb)->mount_crypt_stat;
512         rc = ecryptfs_encrypt_and_encode_filename(&encoded_symname,
513                                                   &encoded_symlen,
514                                                   NULL,
515                                                   mount_crypt_stat, symname,
516                                                   strlen(symname));
517         if (rc)
518                 goto out_lock;
519         rc = vfs_symlink(lower_dir_dentry->d_inode, lower_dentry,
520                          encoded_symname);
521         kfree(encoded_symname);
522         if (rc || !lower_dentry->d_inode)
523                 goto out_lock;
524         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
525         if (rc)
526                 goto out_lock;
527         fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
528         fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
529 out_lock:
530         unlock_dir(lower_dir_dentry);
531         dput(lower_dentry);
532         if (!dentry->d_inode)
533                 d_drop(dentry);
534         return rc;
535 }
536
537 static int ecryptfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
538 {
539         int rc;
540         struct dentry *lower_dentry;
541         struct dentry *lower_dir_dentry;
542
543         lower_dentry = ecryptfs_dentry_to_lower(dentry);
544         lower_dir_dentry = lock_parent(lower_dentry);
545         rc = vfs_mkdir(lower_dir_dentry->d_inode, lower_dentry, mode);
546         if (rc || !lower_dentry->d_inode)
547                 goto out;
548         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
549         if (rc)
550                 goto out;
551         fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
552         fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
553         dir->i_nlink = lower_dir_dentry->d_inode->i_nlink;
554 out:
555         unlock_dir(lower_dir_dentry);
556         if (!dentry->d_inode)
557                 d_drop(dentry);
558         return rc;
559 }
560
561 static int ecryptfs_rmdir(struct inode *dir, struct dentry *dentry)
562 {
563         struct dentry *lower_dentry;
564         struct dentry *lower_dir_dentry;
565         int rc;
566
567         lower_dentry = ecryptfs_dentry_to_lower(dentry);
568         dget(dentry);
569         lower_dir_dentry = lock_parent(lower_dentry);
570         dget(lower_dentry);
571         rc = vfs_rmdir(lower_dir_dentry->d_inode, lower_dentry);
572         dput(lower_dentry);
573         if (!rc)
574                 d_delete(lower_dentry);
575         fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
576         dir->i_nlink = lower_dir_dentry->d_inode->i_nlink;
577         unlock_dir(lower_dir_dentry);
578         if (!rc)
579                 d_drop(dentry);
580         dput(dentry);
581         return rc;
582 }
583
584 static int
585 ecryptfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
586 {
587         int rc;
588         struct dentry *lower_dentry;
589         struct dentry *lower_dir_dentry;
590
591         lower_dentry = ecryptfs_dentry_to_lower(dentry);
592         lower_dir_dentry = lock_parent(lower_dentry);
593         rc = vfs_mknod(lower_dir_dentry->d_inode, lower_dentry, mode, dev);
594         if (rc || !lower_dentry->d_inode)
595                 goto out;
596         rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
597         if (rc)
598                 goto out;
599         fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
600         fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
601 out:
602         unlock_dir(lower_dir_dentry);
603         if (!dentry->d_inode)
604                 d_drop(dentry);
605         return rc;
606 }
607
608 static int
609 ecryptfs_rename(struct inode *old_dir, struct dentry *old_dentry,
610                 struct inode *new_dir, struct dentry *new_dentry)
611 {
612         int rc;
613         struct dentry *lower_old_dentry;
614         struct dentry *lower_new_dentry;
615         struct dentry *lower_old_dir_dentry;
616         struct dentry *lower_new_dir_dentry;
617
618         lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
619         lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
620         dget(lower_old_dentry);
621         dget(lower_new_dentry);
622         lower_old_dir_dentry = dget_parent(lower_old_dentry);
623         lower_new_dir_dentry = dget_parent(lower_new_dentry);
624         lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
625         rc = vfs_rename(lower_old_dir_dentry->d_inode, lower_old_dentry,
626                         lower_new_dir_dentry->d_inode, lower_new_dentry);
627         if (rc)
628                 goto out_lock;
629         fsstack_copy_attr_all(new_dir, lower_new_dir_dentry->d_inode);
630         if (new_dir != old_dir)
631                 fsstack_copy_attr_all(old_dir, lower_old_dir_dentry->d_inode);
632 out_lock:
633         unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
634         dput(lower_new_dentry->d_parent);
635         dput(lower_old_dentry->d_parent);
636         dput(lower_new_dentry);
637         dput(lower_old_dentry);
638         return rc;
639 }
640
641 static int
642 ecryptfs_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
643 {
644         char *lower_buf;
645         size_t lower_bufsiz;
646         struct dentry *lower_dentry;
647         struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
648         char *plaintext_name;
649         size_t plaintext_name_size;
650         mm_segment_t old_fs;
651         int rc;
652
653         lower_dentry = ecryptfs_dentry_to_lower(dentry);
654         if (!lower_dentry->d_inode->i_op->readlink) {
655                 rc = -EINVAL;
656                 goto out;
657         }
658         mount_crypt_stat = &ecryptfs_superblock_to_private(
659                                                 dentry->d_sb)->mount_crypt_stat;
660         /*
661          * If the lower filename is encrypted, it will result in a significantly
662          * longer name.  If needed, truncate the name after decode and decrypt.
663          */
664         if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
665                 lower_bufsiz = PATH_MAX;
666         else
667                 lower_bufsiz = bufsiz;
668         /* Released in this function */
669         lower_buf = kmalloc(lower_bufsiz, GFP_KERNEL);
670         if (lower_buf == NULL) {
671                 printk(KERN_ERR "%s: Out of memory whilst attempting to "
672                        "kmalloc [%zd] bytes\n", __func__, lower_bufsiz);
673                 rc = -ENOMEM;
674                 goto out;
675         }
676         old_fs = get_fs();
677         set_fs(get_ds());
678         rc = lower_dentry->d_inode->i_op->readlink(lower_dentry,
679                                                    (char __user *)lower_buf,
680                                                    lower_bufsiz);
681         set_fs(old_fs);
682         if (rc >= 0) {
683                 rc = ecryptfs_decode_and_decrypt_filename(&plaintext_name,
684                                                           &plaintext_name_size,
685                                                           dentry, lower_buf,
686                                                           rc);
687                 if (rc) {
688                         printk(KERN_ERR "%s: Error attempting to decode and "
689                                "decrypt filename; rc = [%d]\n", __func__,
690                                 rc);
691                         goto out_free_lower_buf;
692                 }
693                 /* Check for bufsiz <= 0 done in sys_readlinkat() */
694                 rc = copy_to_user(buf, plaintext_name,
695                                   min((size_t) bufsiz, plaintext_name_size));
696                 if (rc)
697                         rc = -EFAULT;
698                 else
699                         rc = plaintext_name_size;
700                 kfree(plaintext_name);
701                 fsstack_copy_attr_atime(dentry->d_inode, lower_dentry->d_inode);
702         }
703 out_free_lower_buf:
704         kfree(lower_buf);
705 out:
706         return rc;
707 }
708
709 static void *ecryptfs_follow_link(struct dentry *dentry, struct nameidata *nd)
710 {
711         char *buf;
712         int len = PAGE_SIZE, rc;
713         mm_segment_t old_fs;
714
715         /* Released in ecryptfs_put_link(); only release here on error */
716         buf = kmalloc(len, GFP_KERNEL);
717         if (!buf) {
718                 buf = ERR_PTR(-ENOMEM);
719                 goto out;
720         }
721         old_fs = get_fs();
722         set_fs(get_ds());
723         rc = dentry->d_inode->i_op->readlink(dentry, (char __user *)buf, len);
724         set_fs(old_fs);
725         if (rc < 0) {
726                 kfree(buf);
727                 buf = ERR_PTR(rc);
728         } else
729                 buf[rc] = '\0';
730 out:
731         nd_set_link(nd, buf);
732         return NULL;
733 }
734
735 static void
736 ecryptfs_put_link(struct dentry *dentry, struct nameidata *nd, void *ptr)
737 {
738         char *buf = nd_get_link(nd);
739         if (!IS_ERR(buf)) {
740                 /* Free the char* */
741                 kfree(buf);
742         }
743 }
744
745 /**
746  * upper_size_to_lower_size
747  * @crypt_stat: Crypt_stat associated with file
748  * @upper_size: Size of the upper file
749  *
750  * Calculate the required size of the lower file based on the
751  * specified size of the upper file. This calculation is based on the
752  * number of headers in the underlying file and the extent size.
753  *
754  * Returns Calculated size of the lower file.
755  */
756 static loff_t
757 upper_size_to_lower_size(struct ecryptfs_crypt_stat *crypt_stat,
758                          loff_t upper_size)
759 {
760         loff_t lower_size;
761
762         lower_size = crypt_stat->num_header_bytes_at_front;
763         if (upper_size != 0) {
764                 loff_t num_extents;
765
766                 num_extents = upper_size >> crypt_stat->extent_shift;
767                 if (upper_size & ~crypt_stat->extent_mask)
768                         num_extents++;
769                 lower_size += (num_extents * crypt_stat->extent_size);
770         }
771         return lower_size;
772 }
773
774 /**
775  * truncate_upper
776  * @dentry: The ecryptfs layer dentry
777  * @ia: Address of the ecryptfs inode's attributes
778  * @lower_ia: Address of the lower inode's attributes
779  *
780  * Function to handle truncations modifying the size of the file. Note
781  * that the file sizes are interpolated. When expanding, we are simply
782  * writing strings of 0's out. When truncating, we truncate the upper
783  * inode and update the lower_ia according to the page index
784  * interpolations. If ATTR_SIZE is set in lower_ia->ia_valid upon return,
785  * the caller must use lower_ia in a call to notify_change() to perform
786  * the truncation of the lower inode.
787  *
788  * Returns zero on success; non-zero otherwise
789  */
790 static int truncate_upper(struct dentry *dentry, struct iattr *ia,
791                           struct iattr *lower_ia)
792 {
793         int rc = 0;
794         struct inode *inode = dentry->d_inode;
795         struct dentry *lower_dentry;
796         struct file fake_ecryptfs_file;
797         struct ecryptfs_crypt_stat *crypt_stat;
798         loff_t i_size = i_size_read(inode);
799         loff_t lower_size_before_truncate;
800         loff_t lower_size_after_truncate;
801
802         if (unlikely((ia->ia_size == i_size))) {
803                 lower_ia->ia_valid &= ~ATTR_SIZE;
804                 goto out;
805         }
806         crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
807         /* Set up a fake ecryptfs file, this is used to interface with
808          * the file in the underlying filesystem so that the
809          * truncation has an effect there as well. */
810         memset(&fake_ecryptfs_file, 0, sizeof(fake_ecryptfs_file));
811         fake_ecryptfs_file.f_path.dentry = dentry;
812         /* Released at out_free: label */
813         ecryptfs_set_file_private(&fake_ecryptfs_file,
814                                   kmem_cache_alloc(ecryptfs_file_info_cache,
815                                                    GFP_KERNEL));
816         if (unlikely(!ecryptfs_file_to_private(&fake_ecryptfs_file))) {
817                 rc = -ENOMEM;
818                 goto out;
819         }
820         lower_dentry = ecryptfs_dentry_to_lower(dentry);
821         ecryptfs_set_file_lower(
822                 &fake_ecryptfs_file,
823                 ecryptfs_inode_to_private(dentry->d_inode)->lower_file);
824         /* Switch on growing or shrinking file */
825         if (ia->ia_size > i_size) {
826                 char zero[] = { 0x00 };
827
828                 lower_ia->ia_valid &= ~ATTR_SIZE;
829                 /* Write a single 0 at the last position of the file;
830                  * this triggers code that will fill in 0's throughout
831                  * the intermediate portion of the previous end of the
832                  * file and the new and of the file */
833                 rc = ecryptfs_write(&fake_ecryptfs_file, zero,
834                                     (ia->ia_size - 1), 1);
835         } else { /* ia->ia_size < i_size_read(inode) */
836                 /* We're chopping off all the pages down to the page
837                  * in which ia->ia_size is located. Fill in the end of
838                  * that page from (ia->ia_size & ~PAGE_CACHE_MASK) to
839                  * PAGE_CACHE_SIZE with zeros. */
840                 size_t num_zeros = (PAGE_CACHE_SIZE
841                                     - (ia->ia_size & ~PAGE_CACHE_MASK));
842
843                 if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
844                         rc = vmtruncate(inode, ia->ia_size);
845                         if (rc)
846                                 goto out_free;
847                         lower_ia->ia_size = ia->ia_size;
848                         lower_ia->ia_valid |= ATTR_SIZE;
849                         goto out_free;
850                 }
851                 if (num_zeros) {
852                         char *zeros_virt;
853
854                         zeros_virt = kzalloc(num_zeros, GFP_KERNEL);
855                         if (!zeros_virt) {
856                                 rc = -ENOMEM;
857                                 goto out_free;
858                         }
859                         rc = ecryptfs_write(&fake_ecryptfs_file, zeros_virt,
860                                             ia->ia_size, num_zeros);
861                         kfree(zeros_virt);
862                         if (rc) {
863                                 printk(KERN_ERR "Error attempting to zero out "
864                                        "the remainder of the end page on "
865                                        "reducing truncate; rc = [%d]\n", rc);
866                                 goto out_free;
867                         }
868                 }
869                 vmtruncate(inode, ia->ia_size);
870                 rc = ecryptfs_write_inode_size_to_metadata(inode);
871                 if (rc) {
872                         printk(KERN_ERR "Problem with "
873                                "ecryptfs_write_inode_size_to_metadata; "
874                                "rc = [%d]\n", rc);
875                         goto out_free;
876                 }
877                 /* We are reducing the size of the ecryptfs file, and need to
878                  * know if we need to reduce the size of the lower file. */
879                 lower_size_before_truncate =
880                     upper_size_to_lower_size(crypt_stat, i_size);
881                 lower_size_after_truncate =
882                     upper_size_to_lower_size(crypt_stat, ia->ia_size);
883                 if (lower_size_after_truncate < lower_size_before_truncate) {
884                         lower_ia->ia_size = lower_size_after_truncate;
885                         lower_ia->ia_valid |= ATTR_SIZE;
886                 } else
887                         lower_ia->ia_valid &= ~ATTR_SIZE;
888         }
889 out_free:
890         if (ecryptfs_file_to_private(&fake_ecryptfs_file))
891                 kmem_cache_free(ecryptfs_file_info_cache,
892                                 ecryptfs_file_to_private(&fake_ecryptfs_file));
893 out:
894         return rc;
895 }
896
897 /**
898  * ecryptfs_truncate
899  * @dentry: The ecryptfs layer dentry
900  * @new_length: The length to expand the file to
901  *
902  * Simple function that handles the truncation of an eCryptfs inode and
903  * its corresponding lower inode.
904  *
905  * Returns zero on success; non-zero otherwise
906  */
907 int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
908 {
909         struct iattr ia = { .ia_valid = ATTR_SIZE, .ia_size = new_length };
910         struct iattr lower_ia = { .ia_valid = 0 };
911         int rc;
912
913         rc = truncate_upper(dentry, &ia, &lower_ia);
914         if (!rc && lower_ia.ia_valid & ATTR_SIZE) {
915                 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
916
917                 mutex_lock(&lower_dentry->d_inode->i_mutex);
918                 rc = notify_change(lower_dentry, &lower_ia);
919                 mutex_unlock(&lower_dentry->d_inode->i_mutex);
920         }
921         return rc;
922 }
923
924 static int
925 ecryptfs_permission(struct inode *inode, int mask)
926 {
927         return inode_permission(ecryptfs_inode_to_lower(inode), mask);
928 }
929
930 /**
931  * ecryptfs_setattr
932  * @dentry: dentry handle to the inode to modify
933  * @ia: Structure with flags of what to change and values
934  *
935  * Updates the metadata of an inode. If the update is to the size
936  * i.e. truncation, then ecryptfs_truncate will handle the size modification
937  * of both the ecryptfs inode and the lower inode.
938  *
939  * All other metadata changes will be passed right to the lower filesystem,
940  * and we will just update our inode to look like the lower.
941  */
942 static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
943 {
944         int rc = 0;
945         struct dentry *lower_dentry;
946         struct iattr lower_ia;
947         struct inode *inode;
948         struct inode *lower_inode;
949         struct ecryptfs_crypt_stat *crypt_stat;
950
951         crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
952         if (!(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED))
953                 ecryptfs_init_crypt_stat(crypt_stat);
954         inode = dentry->d_inode;
955         lower_inode = ecryptfs_inode_to_lower(inode);
956         lower_dentry = ecryptfs_dentry_to_lower(dentry);
957         mutex_lock(&crypt_stat->cs_mutex);
958         if (S_ISDIR(dentry->d_inode->i_mode))
959                 crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
960         else if (S_ISREG(dentry->d_inode->i_mode)
961                  && (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
962                      || !(crypt_stat->flags & ECRYPTFS_KEY_VALID))) {
963                 struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
964
965                 mount_crypt_stat = &ecryptfs_superblock_to_private(
966                         dentry->d_sb)->mount_crypt_stat;
967                 rc = ecryptfs_read_metadata(dentry);
968                 if (rc) {
969                         if (!(mount_crypt_stat->flags
970                               & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
971                                 rc = -EIO;
972                                 printk(KERN_WARNING "Either the lower file "
973                                        "is not in a valid eCryptfs format, "
974                                        "or the key could not be retrieved. "
975                                        "Plaintext passthrough mode is not "
976                                        "enabled; returning -EIO\n");
977                                 mutex_unlock(&crypt_stat->cs_mutex);
978                                 goto out;
979                         }
980                         rc = 0;
981                         crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
982                 }
983         }
984         mutex_unlock(&crypt_stat->cs_mutex);
985         memcpy(&lower_ia, ia, sizeof(lower_ia));
986         if (ia->ia_valid & ATTR_FILE)
987                 lower_ia.ia_file = ecryptfs_file_to_lower(ia->ia_file);
988         if (ia->ia_valid & ATTR_SIZE) {
989                 rc = truncate_upper(dentry, ia, &lower_ia);
990                 if (rc < 0)
991                         goto out;
992         }
993
994         /*
995          * mode change is for clearing setuid/setgid bits. Allow lower fs
996          * to interpret this in its own way.
997          */
998         if (lower_ia.ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
999                 lower_ia.ia_valid &= ~ATTR_MODE;
1000
1001         mutex_lock(&lower_dentry->d_inode->i_mutex);
1002         rc = notify_change(lower_dentry, &lower_ia);
1003         mutex_unlock(&lower_dentry->d_inode->i_mutex);
1004 out:
1005         fsstack_copy_attr_all(inode, lower_inode);
1006         return rc;
1007 }
1008
1009 int ecryptfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
1010                      struct kstat *stat)
1011 {
1012         struct kstat lower_stat;
1013         int rc;
1014
1015         rc = vfs_getattr(ecryptfs_dentry_to_lower_mnt(dentry),
1016                          ecryptfs_dentry_to_lower(dentry), &lower_stat);
1017         if (!rc) {
1018                 generic_fillattr(dentry->d_inode, stat);
1019                 stat->blocks = lower_stat.blocks;
1020         }
1021         return rc;
1022 }
1023
1024 int
1025 ecryptfs_setxattr(struct dentry *dentry, const char *name, const void *value,
1026                   size_t size, int flags)
1027 {
1028         int rc = 0;
1029         struct dentry *lower_dentry;
1030
1031         lower_dentry = ecryptfs_dentry_to_lower(dentry);
1032         if (!lower_dentry->d_inode->i_op->setxattr) {
1033                 rc = -ENOSYS;
1034                 goto out;
1035         }
1036         mutex_lock(&lower_dentry->d_inode->i_mutex);
1037         rc = lower_dentry->d_inode->i_op->setxattr(lower_dentry, name, value,
1038                                                    size, flags);
1039         mutex_unlock(&lower_dentry->d_inode->i_mutex);
1040 out:
1041         return rc;
1042 }
1043
1044 ssize_t
1045 ecryptfs_getxattr_lower(struct dentry *lower_dentry, const char *name,
1046                         void *value, size_t size)
1047 {
1048         int rc = 0;
1049
1050         if (!lower_dentry->d_inode->i_op->getxattr) {
1051                 rc = -ENOSYS;
1052                 goto out;
1053         }
1054         mutex_lock(&lower_dentry->d_inode->i_mutex);
1055         rc = lower_dentry->d_inode->i_op->getxattr(lower_dentry, name, value,
1056                                                    size);
1057         mutex_unlock(&lower_dentry->d_inode->i_mutex);
1058 out:
1059         return rc;
1060 }
1061
1062 static ssize_t
1063 ecryptfs_getxattr(struct dentry *dentry, const char *name, void *value,
1064                   size_t size)
1065 {
1066         return ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry), name,
1067                                        value, size);
1068 }
1069
1070 static ssize_t
1071 ecryptfs_listxattr(struct dentry *dentry, char *list, size_t size)
1072 {
1073         int rc = 0;
1074         struct dentry *lower_dentry;
1075
1076         lower_dentry = ecryptfs_dentry_to_lower(dentry);
1077         if (!lower_dentry->d_inode->i_op->listxattr) {
1078                 rc = -ENOSYS;
1079                 goto out;
1080         }
1081         mutex_lock(&lower_dentry->d_inode->i_mutex);
1082         rc = lower_dentry->d_inode->i_op->listxattr(lower_dentry, list, size);
1083         mutex_unlock(&lower_dentry->d_inode->i_mutex);
1084 out:
1085         return rc;
1086 }
1087
1088 static int ecryptfs_removexattr(struct dentry *dentry, const char *name)
1089 {
1090         int rc = 0;
1091         struct dentry *lower_dentry;
1092
1093         lower_dentry = ecryptfs_dentry_to_lower(dentry);
1094         if (!lower_dentry->d_inode->i_op->removexattr) {
1095                 rc = -ENOSYS;
1096                 goto out;
1097         }
1098         mutex_lock(&lower_dentry->d_inode->i_mutex);
1099         rc = lower_dentry->d_inode->i_op->removexattr(lower_dentry, name);
1100         mutex_unlock(&lower_dentry->d_inode->i_mutex);
1101 out:
1102         return rc;
1103 }
1104
1105 int ecryptfs_inode_test(struct inode *inode, void *candidate_lower_inode)
1106 {
1107         if ((ecryptfs_inode_to_lower(inode)
1108              == (struct inode *)candidate_lower_inode))
1109                 return 1;
1110         else
1111                 return 0;
1112 }
1113
1114 int ecryptfs_inode_set(struct inode *inode, void *lower_inode)
1115 {
1116         ecryptfs_init_inode(inode, (struct inode *)lower_inode);
1117         return 0;
1118 }
1119
1120 const struct inode_operations ecryptfs_symlink_iops = {
1121         .readlink = ecryptfs_readlink,
1122         .follow_link = ecryptfs_follow_link,
1123         .put_link = ecryptfs_put_link,
1124         .permission = ecryptfs_permission,
1125         .setattr = ecryptfs_setattr,
1126         .setxattr = ecryptfs_setxattr,
1127         .getxattr = ecryptfs_getxattr,
1128         .listxattr = ecryptfs_listxattr,
1129         .removexattr = ecryptfs_removexattr
1130 };
1131
1132 const struct inode_operations ecryptfs_dir_iops = {
1133         .create = ecryptfs_create,
1134         .lookup = ecryptfs_lookup,
1135         .link = ecryptfs_link,
1136         .unlink = ecryptfs_unlink,
1137         .symlink = ecryptfs_symlink,
1138         .mkdir = ecryptfs_mkdir,
1139         .rmdir = ecryptfs_rmdir,
1140         .mknod = ecryptfs_mknod,
1141         .rename = ecryptfs_rename,
1142         .permission = ecryptfs_permission,
1143         .setattr = ecryptfs_setattr,
1144         .setxattr = ecryptfs_setxattr,
1145         .getxattr = ecryptfs_getxattr,
1146         .listxattr = ecryptfs_listxattr,
1147         .removexattr = ecryptfs_removexattr
1148 };
1149
1150 const struct inode_operations ecryptfs_main_iops = {
1151         .permission = ecryptfs_permission,
1152         .setattr = ecryptfs_setattr,
1153         .getattr = ecryptfs_getattr,
1154         .setxattr = ecryptfs_setxattr,
1155         .getxattr = ecryptfs_getxattr,
1156         .listxattr = ecryptfs_listxattr,
1157         .removexattr = ecryptfs_removexattr
1158 };