Merge branch 'for-2.6.23' into merge
[linux-2.6] / fs / ecryptfs / mmap.c
1 /**
2  * eCryptfs: Linux filesystem encryption layer
3  * This is where eCryptfs coordinates the symmetric encryption and
4  * decryption of the file data as it passes between the lower
5  * encrypted file and the upper decrypted file.
6  *
7  * Copyright (C) 1997-2003 Erez Zadok
8  * Copyright (C) 2001-2003 Stony Brook University
9  * Copyright (C) 2004-2007 International Business Machines Corp.
10  *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
11  *
12  * This program is free software; you can redistribute it and/or
13  * modify it under the terms of the GNU General Public License as
14  * published by the Free Software Foundation; either version 2 of the
15  * License, or (at your option) any later version.
16  *
17  * This program is distributed in the hope that it will be useful, but
18  * WITHOUT ANY WARRANTY; without even the implied warranty of
19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
20  * General Public License for more details.
21  *
22  * You should have received a copy of the GNU General Public License
23  * along with this program; if not, write to the Free Software
24  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
25  * 02111-1307, USA.
26  */
27
28 #include <linux/pagemap.h>
29 #include <linux/writeback.h>
30 #include <linux/page-flags.h>
31 #include <linux/mount.h>
32 #include <linux/file.h>
33 #include <linux/crypto.h>
34 #include <linux/scatterlist.h>
35 #include "ecryptfs_kernel.h"
36
37 struct kmem_cache *ecryptfs_lower_page_cache;
38
39 /**
40  * ecryptfs_get1page
41  *
42  * Get one page from cache or lower f/s, return error otherwise.
43  *
44  * Returns unlocked and up-to-date page (if ok), with increased
45  * refcnt.
46  */
47 static struct page *ecryptfs_get1page(struct file *file, int index)
48 {
49         struct dentry *dentry;
50         struct inode *inode;
51         struct address_space *mapping;
52
53         dentry = file->f_path.dentry;
54         inode = dentry->d_inode;
55         mapping = inode->i_mapping;
56         return read_mapping_page(mapping, index, (void *)file);
57 }
58
59 /**
60  * ecryptfs_fill_zeros
61  * @file: The ecryptfs file
62  * @new_length: The new length of the data in the underlying file;
63  *              everything between the prior end of the file and the
64  *              new end of the file will be filled with zero's.
65  *              new_length must be greater than  current length
66  *
67  * Function for handling lseek-ing past the end of the file.
68  *
69  * This function does not support shrinking, only growing a file.
70  *
71  * Returns zero on success; non-zero otherwise.
72  */
73 int ecryptfs_fill_zeros(struct file *file, loff_t new_length)
74 {
75         int rc = 0;
76         struct dentry *dentry = file->f_path.dentry;
77         struct inode *inode = dentry->d_inode;
78         pgoff_t old_end_page_index = 0;
79         pgoff_t index = old_end_page_index;
80         int old_end_pos_in_page = -1;
81         pgoff_t new_end_page_index;
82         int new_end_pos_in_page;
83         loff_t cur_length = i_size_read(inode);
84
85         if (cur_length != 0) {
86                 index = old_end_page_index =
87                     ((cur_length - 1) >> PAGE_CACHE_SHIFT);
88                 old_end_pos_in_page = ((cur_length - 1) & ~PAGE_CACHE_MASK);
89         }
90         new_end_page_index = ((new_length - 1) >> PAGE_CACHE_SHIFT);
91         new_end_pos_in_page = ((new_length - 1) & ~PAGE_CACHE_MASK);
92         ecryptfs_printk(KERN_DEBUG, "old_end_page_index = [0x%.16x]; "
93                         "old_end_pos_in_page = [%d]; "
94                         "new_end_page_index = [0x%.16x]; "
95                         "new_end_pos_in_page = [%d]\n",
96                         old_end_page_index, old_end_pos_in_page,
97                         new_end_page_index, new_end_pos_in_page);
98         if (old_end_page_index == new_end_page_index) {
99                 /* Start and end are in the same page; we just need to
100                  * set a portion of the existing page to zero's */
101                 rc = ecryptfs_write_zeros(file, index,
102                                           (old_end_pos_in_page + 1),
103                                           (new_end_pos_in_page
104                                            - old_end_pos_in_page));
105                 if (rc)
106                         ecryptfs_printk(KERN_ERR, "ecryptfs_write_zeros("
107                                         "file=[%p], "
108                                         "index=[0x%.16x], "
109                                         "old_end_pos_in_page=[d], "
110                                         "(PAGE_CACHE_SIZE - new_end_pos_in_page"
111                                         "=[%d]"
112                                         ")=[d]) returned [%d]\n", file, index,
113                                         old_end_pos_in_page,
114                                         new_end_pos_in_page,
115                                         (PAGE_CACHE_SIZE - new_end_pos_in_page),
116                                         rc);
117                 goto out;
118         }
119         /* Fill the remainder of the previous last page with zeros */
120         rc = ecryptfs_write_zeros(file, index, (old_end_pos_in_page + 1),
121                          ((PAGE_CACHE_SIZE - 1) - old_end_pos_in_page));
122         if (rc) {
123                 ecryptfs_printk(KERN_ERR, "ecryptfs_write_zeros(file=[%p], "
124                                 "index=[0x%.16x], old_end_pos_in_page=[d], "
125                                 "(PAGE_CACHE_SIZE - old_end_pos_in_page)=[d]) "
126                                 "returned [%d]\n", file, index,
127                                 old_end_pos_in_page,
128                                 (PAGE_CACHE_SIZE - old_end_pos_in_page), rc);
129                 goto out;
130         }
131         index++;
132         while (index < new_end_page_index) {
133                 /* Fill all intermediate pages with zeros */
134                 rc = ecryptfs_write_zeros(file, index, 0, PAGE_CACHE_SIZE);
135                 if (rc) {
136                         ecryptfs_printk(KERN_ERR, "ecryptfs_write_zeros("
137                                         "file=[%p], "
138                                         "index=[0x%.16x], "
139                                         "old_end_pos_in_page=[d], "
140                                         "(PAGE_CACHE_SIZE - new_end_pos_in_page"
141                                         "=[%d]"
142                                         ")=[d]) returned [%d]\n", file, index,
143                                         old_end_pos_in_page,
144                                         new_end_pos_in_page,
145                                         (PAGE_CACHE_SIZE - new_end_pos_in_page),
146                                         rc);
147                         goto out;
148                 }
149                 index++;
150         }
151         /* Fill the portion at the beginning of the last new page with
152          * zero's */
153         rc = ecryptfs_write_zeros(file, index, 0, (new_end_pos_in_page + 1));
154         if (rc) {
155                 ecryptfs_printk(KERN_ERR, "ecryptfs_write_zeros(file="
156                                 "[%p], index=[0x%.16x], 0, "
157                                 "new_end_pos_in_page=[%d]"
158                                 "returned [%d]\n", file, index,
159                                 new_end_pos_in_page, rc);
160                 goto out;
161         }
162 out:
163         return rc;
164 }
165
166 /**
167  * ecryptfs_writepage
168  * @page: Page that is locked before this call is made
169  *
170  * Returns zero on success; non-zero otherwise
171  */
172 static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
173 {
174         struct ecryptfs_page_crypt_context ctx;
175         int rc;
176
177         ctx.page = page;
178         ctx.mode = ECRYPTFS_WRITEPAGE_MODE;
179         ctx.param.wbc = wbc;
180         rc = ecryptfs_encrypt_page(&ctx);
181         if (rc) {
182                 ecryptfs_printk(KERN_WARNING, "Error encrypting "
183                                 "page (upper index [0x%.16x])\n", page->index);
184                 ClearPageUptodate(page);
185                 goto out;
186         }
187         SetPageUptodate(page);
188         unlock_page(page);
189 out:
190         return rc;
191 }
192
193 /**
194  * Reads the data from the lower file file at index lower_page_index
195  * and copies that data into page.
196  *
197  * @param page  Page to fill
198  * @param lower_page_index Index of the page in the lower file to get
199  */
200 int ecryptfs_do_readpage(struct file *file, struct page *page,
201                          pgoff_t lower_page_index)
202 {
203         int rc;
204         struct dentry *dentry;
205         struct file *lower_file;
206         struct dentry *lower_dentry;
207         struct inode *inode;
208         struct inode *lower_inode;
209         char *page_data;
210         struct page *lower_page = NULL;
211         char *lower_page_data;
212         const struct address_space_operations *lower_a_ops;
213
214         dentry = file->f_path.dentry;
215         lower_file = ecryptfs_file_to_lower(file);
216         lower_dentry = ecryptfs_dentry_to_lower(dentry);
217         inode = dentry->d_inode;
218         lower_inode = ecryptfs_inode_to_lower(inode);
219         lower_a_ops = lower_inode->i_mapping->a_ops;
220         lower_page = read_cache_page(lower_inode->i_mapping, lower_page_index,
221                                      (filler_t *)lower_a_ops->readpage,
222                                      (void *)lower_file);
223         if (IS_ERR(lower_page)) {
224                 rc = PTR_ERR(lower_page);
225                 lower_page = NULL;
226                 ecryptfs_printk(KERN_ERR, "Error reading from page cache\n");
227                 goto out;
228         }
229         page_data = kmap_atomic(page, KM_USER0);
230         lower_page_data = kmap_atomic(lower_page, KM_USER1);
231         memcpy(page_data, lower_page_data, PAGE_CACHE_SIZE);
232         kunmap_atomic(lower_page_data, KM_USER1);
233         kunmap_atomic(page_data, KM_USER0);
234         flush_dcache_page(page);
235         rc = 0;
236 out:
237         if (likely(lower_page))
238                 page_cache_release(lower_page);
239         if (rc == 0)
240                 SetPageUptodate(page);
241         else
242                 ClearPageUptodate(page);
243         return rc;
244 }
245 /**
246  *   Header Extent:
247  *     Octets 0-7:        Unencrypted file size (big-endian)
248  *     Octets 8-15:       eCryptfs special marker
249  *     Octets 16-19:      Flags
250  *      Octet 16:         File format version number (between 0 and 255)
251  *      Octets 17-18:     Reserved
252  *      Octet 19:         Bit 1 (lsb): Reserved
253  *                        Bit 2: Encrypted?
254  *                        Bits 3-8: Reserved
255  *     Octets 20-23:      Header extent size (big-endian)
256  *     Octets 24-25:      Number of header extents at front of file
257  *                        (big-endian)
258  *     Octet  26:         Begin RFC 2440 authentication token packet set
259  */
260 static void set_header_info(char *page_virt,
261                             struct ecryptfs_crypt_stat *crypt_stat)
262 {
263         size_t written;
264         int save_num_header_extents_at_front =
265                 crypt_stat->num_header_extents_at_front;
266
267         crypt_stat->num_header_extents_at_front = 1;
268         ecryptfs_write_header_metadata(page_virt + 20, crypt_stat, &written);
269         crypt_stat->num_header_extents_at_front =
270                 save_num_header_extents_at_front;
271 }
272
273 /**
274  * ecryptfs_readpage
275  * @file: This is an ecryptfs file
276  * @page: ecryptfs associated page to stick the read data into
277  *
278  * Read in a page, decrypting if necessary.
279  *
280  * Returns zero on success; non-zero on error.
281  */
282 static int ecryptfs_readpage(struct file *file, struct page *page)
283 {
284         int rc = 0;
285         struct ecryptfs_crypt_stat *crypt_stat;
286
287         BUG_ON(!(file && file->f_path.dentry && file->f_path.dentry->d_inode));
288         crypt_stat = &ecryptfs_inode_to_private(file->f_path.dentry->d_inode)
289                         ->crypt_stat;
290         if (!crypt_stat
291             || !(crypt_stat->flags & ECRYPTFS_ENCRYPTED)
292             || (crypt_stat->flags & ECRYPTFS_NEW_FILE)) {
293                 ecryptfs_printk(KERN_DEBUG,
294                                 "Passing through unencrypted page\n");
295                 rc = ecryptfs_do_readpage(file, page, page->index);
296                 if (rc) {
297                         ecryptfs_printk(KERN_ERR, "Error reading page; rc = "
298                                         "[%d]\n", rc);
299                         goto out;
300                 }
301         } else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
302                 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
303                         int num_pages_in_header_region =
304                                 (crypt_stat->header_extent_size
305                                  / PAGE_CACHE_SIZE);
306
307                         if (page->index < num_pages_in_header_region) {
308                                 char *page_virt;
309
310                                 page_virt = kmap_atomic(page, KM_USER0);
311                                 memset(page_virt, 0, PAGE_CACHE_SIZE);
312                                 if (page->index == 0) {
313                                         rc = ecryptfs_read_xattr_region(
314                                                 page_virt, file->f_path.dentry);
315                                         set_header_info(page_virt, crypt_stat);
316                                 }
317                                 kunmap_atomic(page_virt, KM_USER0);
318                                 flush_dcache_page(page);
319                                 if (rc) {
320                                         printk(KERN_ERR "Error reading xattr "
321                                                "region\n");
322                                         goto out;
323                                 }
324                         } else {
325                                 rc = ecryptfs_do_readpage(
326                                         file, page,
327                                         (page->index
328                                          - num_pages_in_header_region));
329                                 if (rc) {
330                                         printk(KERN_ERR "Error reading page; "
331                                                "rc = [%d]\n", rc);
332                                         goto out;
333                                 }
334                         }
335                 } else {
336                         rc = ecryptfs_do_readpage(file, page, page->index);
337                         if (rc) {
338                                 printk(KERN_ERR "Error reading page; rc = "
339                                        "[%d]\n", rc);
340                                 goto out;
341                         }
342                 }
343         } else {
344                 rc = ecryptfs_decrypt_page(file, page);
345                 if (rc) {
346                         ecryptfs_printk(KERN_ERR, "Error decrypting page; "
347                                         "rc = [%d]\n", rc);
348                         goto out;
349                 }
350         }
351         SetPageUptodate(page);
352 out:
353         if (rc)
354                 ClearPageUptodate(page);
355         ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
356                         page->index);
357         unlock_page(page);
358         return rc;
359 }
360
361 /**
362  * Called with lower inode mutex held.
363  */
364 static int fill_zeros_to_end_of_page(struct page *page, unsigned int to)
365 {
366         struct inode *inode = page->mapping->host;
367         int end_byte_in_page;
368
369         if ((i_size_read(inode) / PAGE_CACHE_SIZE) != page->index)
370                 goto out;
371         end_byte_in_page = i_size_read(inode) % PAGE_CACHE_SIZE;
372         if (to > end_byte_in_page)
373                 end_byte_in_page = to;
374         zero_user_page(page, end_byte_in_page,
375                 PAGE_CACHE_SIZE - end_byte_in_page, KM_USER0);
376 out:
377         return 0;
378 }
379
380 /**
381  * eCryptfs does not currently support holes. When writing after a
382  * seek past the end of the file, eCryptfs fills in 0's through to the
383  * current location. The code to fill in the 0's to all the
384  * intermediate pages calls ecryptfs_prepare_write_no_truncate().
385  */
386 static int
387 ecryptfs_prepare_write_no_truncate(struct file *file, struct page *page,
388                                    unsigned from, unsigned to)
389 {
390         int rc = 0;
391
392         if (from == 0 && to == PAGE_CACHE_SIZE)
393                 goto out;       /* If we are writing a full page, it will be
394                                    up to date. */
395         if (!PageUptodate(page))
396                 rc = ecryptfs_do_readpage(file, page, page->index);
397 out:
398         return rc;
399 }
400
401 static int ecryptfs_prepare_write(struct file *file, struct page *page,
402                                   unsigned from, unsigned to)
403 {
404         int rc = 0;
405
406         if (from == 0 && to == PAGE_CACHE_SIZE)
407                 goto out;       /* If we are writing a full page, it will be
408                                    up to date. */
409         if (!PageUptodate(page))
410                 rc = ecryptfs_do_readpage(file, page, page->index);
411         if (page->index != 0) {
412                 loff_t end_of_prev_pg_pos =
413                         (((loff_t)page->index << PAGE_CACHE_SHIFT) - 1);
414
415                 if (end_of_prev_pg_pos > i_size_read(page->mapping->host)) {
416                         rc = ecryptfs_truncate(file->f_path.dentry,
417                                                end_of_prev_pg_pos);
418                         if (rc) {
419                                 printk(KERN_ERR "Error on attempt to "
420                                        "truncate to (higher) offset [%lld];"
421                                        " rc = [%d]\n", end_of_prev_pg_pos, rc);
422                                 goto out;
423                         }
424                 }
425                 if (end_of_prev_pg_pos + 1 > i_size_read(page->mapping->host))
426                         zero_user_page(page, 0, PAGE_CACHE_SIZE, KM_USER0);
427         }
428 out:
429         return rc;
430 }
431
432 int ecryptfs_writepage_and_release_lower_page(struct page *lower_page,
433                                               struct inode *lower_inode,
434                                               struct writeback_control *wbc)
435 {
436         int rc = 0;
437
438         rc = lower_inode->i_mapping->a_ops->writepage(lower_page, wbc);
439         if (rc) {
440                 ecryptfs_printk(KERN_ERR, "Error calling lower writepage(); "
441                                 "rc = [%d]\n", rc);
442                 goto out;
443         }
444         lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
445         page_cache_release(lower_page);
446 out:
447         return rc;
448 }
449
450 static
451 void ecryptfs_release_lower_page(struct page *lower_page, int page_locked)
452 {
453         if (page_locked)
454                 unlock_page(lower_page);
455         page_cache_release(lower_page);
456 }
457
458 /**
459  * ecryptfs_write_inode_size_to_header
460  *
461  * Writes the lower file size to the first 8 bytes of the header.
462  *
463  * Returns zero on success; non-zero on error.
464  */
465 static int ecryptfs_write_inode_size_to_header(struct file *lower_file,
466                                                struct inode *lower_inode,
467                                                struct inode *inode)
468 {
469         int rc = 0;
470         struct page *header_page;
471         char *header_virt;
472         const struct address_space_operations *lower_a_ops;
473         u64 file_size;
474
475 retry:
476         header_page = grab_cache_page(lower_inode->i_mapping, 0);
477         if (!header_page) {
478                 ecryptfs_printk(KERN_ERR, "grab_cache_page for "
479                                 "lower_page_index 0 failed\n");
480                 rc = -EINVAL;
481                 goto out;
482         }
483         lower_a_ops = lower_inode->i_mapping->a_ops;
484         rc = lower_a_ops->prepare_write(lower_file, header_page, 0, 8);
485         if (rc) {
486                 if (rc == AOP_TRUNCATED_PAGE) {
487                         ecryptfs_release_lower_page(header_page, 0);
488                         goto retry;
489                 } else
490                         ecryptfs_release_lower_page(header_page, 1);
491                 goto out;
492         }
493         file_size = (u64)i_size_read(inode);
494         ecryptfs_printk(KERN_DEBUG, "Writing size: [0x%.16x]\n", file_size);
495         file_size = cpu_to_be64(file_size);
496         header_virt = kmap_atomic(header_page, KM_USER0);
497         memcpy(header_virt, &file_size, sizeof(u64));
498         kunmap_atomic(header_virt, KM_USER0);
499         flush_dcache_page(header_page);
500         rc = lower_a_ops->commit_write(lower_file, header_page, 0, 8);
501         if (rc < 0)
502                 ecryptfs_printk(KERN_ERR, "Error commiting header page "
503                                 "write\n");
504         if (rc == AOP_TRUNCATED_PAGE) {
505                 ecryptfs_release_lower_page(header_page, 0);
506                 goto retry;
507         } else
508                 ecryptfs_release_lower_page(header_page, 1);
509         lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
510         mark_inode_dirty_sync(inode);
511 out:
512         return rc;
513 }
514
515 static int ecryptfs_write_inode_size_to_xattr(struct inode *lower_inode,
516                                               struct inode *inode,
517                                               struct dentry *ecryptfs_dentry,
518                                               int lower_i_mutex_held)
519 {
520         ssize_t size;
521         void *xattr_virt;
522         struct dentry *lower_dentry;
523         u64 file_size;
524         int rc;
525
526         xattr_virt = kmem_cache_alloc(ecryptfs_xattr_cache, GFP_KERNEL);
527         if (!xattr_virt) {
528                 printk(KERN_ERR "Out of memory whilst attempting to write "
529                        "inode size to xattr\n");
530                 rc = -ENOMEM;
531                 goto out;
532         }
533         lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
534         if (!lower_dentry->d_inode->i_op->getxattr ||
535                         !lower_dentry->d_inode->i_op->setxattr) {
536                 printk(KERN_WARNING
537                        "No support for setting xattr in lower filesystem\n");
538                 rc = -ENOSYS;
539                 kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
540                 goto out;
541         }
542         if (!lower_i_mutex_held)
543                 mutex_lock(&lower_dentry->d_inode->i_mutex);
544         size = lower_dentry->d_inode->i_op->getxattr(lower_dentry,
545                                                      ECRYPTFS_XATTR_NAME,
546                                                      xattr_virt,
547                                                      PAGE_CACHE_SIZE);
548         if (!lower_i_mutex_held)
549                 mutex_unlock(&lower_dentry->d_inode->i_mutex);
550         if (size < 0)
551                 size = 8;
552         file_size = (u64)i_size_read(inode);
553         file_size = cpu_to_be64(file_size);
554         memcpy(xattr_virt, &file_size, sizeof(u64));
555         if (!lower_i_mutex_held)
556                 mutex_lock(&lower_dentry->d_inode->i_mutex);
557         rc = lower_dentry->d_inode->i_op->setxattr(lower_dentry,
558                                                    ECRYPTFS_XATTR_NAME,
559                                                    xattr_virt, size, 0);
560         if (!lower_i_mutex_held)
561                 mutex_unlock(&lower_dentry->d_inode->i_mutex);
562         if (rc)
563                 printk(KERN_ERR "Error whilst attempting to write inode size "
564                        "to lower file xattr; rc = [%d]\n", rc);
565         kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
566 out:
567         return rc;
568 }
569
570 int
571 ecryptfs_write_inode_size_to_metadata(struct file *lower_file,
572                                       struct inode *lower_inode,
573                                       struct inode *inode,
574                                       struct dentry *ecryptfs_dentry,
575                                       int lower_i_mutex_held)
576 {
577         struct ecryptfs_crypt_stat *crypt_stat;
578
579         crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
580         if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
581                 return ecryptfs_write_inode_size_to_xattr(lower_inode, inode,
582                                                           ecryptfs_dentry,
583                                                           lower_i_mutex_held);
584         else
585                 return ecryptfs_write_inode_size_to_header(lower_file,
586                                                            lower_inode,
587                                                            inode);
588 }
589
590 int ecryptfs_get_lower_page(struct page **lower_page, struct inode *lower_inode,
591                             struct file *lower_file,
592                             unsigned long lower_page_index, int byte_offset,
593                             int region_bytes)
594 {
595         int rc = 0;
596
597 retry:
598         *lower_page = grab_cache_page(lower_inode->i_mapping, lower_page_index);
599         if (!(*lower_page)) {
600                 rc = -EINVAL;
601                 ecryptfs_printk(KERN_ERR, "Error attempting to grab "
602                                 "lower page with index [0x%.16x]\n",
603                                 lower_page_index);
604                 goto out;
605         }
606         rc = lower_inode->i_mapping->a_ops->prepare_write(lower_file,
607                                                           (*lower_page),
608                                                           byte_offset,
609                                                           region_bytes);
610         if (rc) {
611                 if (rc == AOP_TRUNCATED_PAGE) {
612                         ecryptfs_release_lower_page(*lower_page, 0);
613                         goto retry;
614                 } else {
615                         ecryptfs_printk(KERN_ERR, "prepare_write for "
616                                 "lower_page_index = [0x%.16x] failed; rc = "
617                                 "[%d]\n", lower_page_index, rc);
618                         ecryptfs_release_lower_page(*lower_page, 1);
619                         (*lower_page) = NULL;
620                 }
621         }
622 out:
623         return rc;
624 }
625
626 /**
627  * ecryptfs_commit_lower_page
628  *
629  * Returns zero on success; non-zero on error
630  */
631 int
632 ecryptfs_commit_lower_page(struct page *lower_page, struct inode *lower_inode,
633                            struct file *lower_file, int byte_offset,
634                            int region_size)
635 {
636         int page_locked = 1;
637         int rc = 0;
638
639         rc = lower_inode->i_mapping->a_ops->commit_write(
640                 lower_file, lower_page, byte_offset, region_size);
641         if (rc == AOP_TRUNCATED_PAGE)
642                 page_locked = 0;
643         if (rc < 0) {
644                 ecryptfs_printk(KERN_ERR,
645                                 "Error committing write; rc = [%d]\n", rc);
646         } else
647                 rc = 0;
648         ecryptfs_release_lower_page(lower_page, page_locked);
649         return rc;
650 }
651
652 /**
653  * ecryptfs_copy_page_to_lower
654  *
655  * Used for plaintext pass-through; no page index interpolation
656  * required.
657  */
658 int ecryptfs_copy_page_to_lower(struct page *page, struct inode *lower_inode,
659                                 struct file *lower_file)
660 {
661         int rc = 0;
662         struct page *lower_page;
663
664         rc = ecryptfs_get_lower_page(&lower_page, lower_inode, lower_file,
665                                      page->index, 0, PAGE_CACHE_SIZE);
666         if (rc) {
667                 ecryptfs_printk(KERN_ERR, "Error attempting to get page "
668                                 "at index [0x%.16x]\n", page->index);
669                 goto out;
670         }
671         /* TODO: aops */
672         memcpy((char *)page_address(lower_page), page_address(page),
673                PAGE_CACHE_SIZE);
674         rc = ecryptfs_commit_lower_page(lower_page, lower_inode, lower_file,
675                                         0, PAGE_CACHE_SIZE);
676         if (rc)
677                 ecryptfs_printk(KERN_ERR, "Error attempting to commit page "
678                                 "at index [0x%.16x]\n", page->index);
679 out:
680         return rc;
681 }
682
683 struct kmem_cache *ecryptfs_xattr_cache;
684
685 /**
686  * ecryptfs_commit_write
687  * @file: The eCryptfs file object
688  * @page: The eCryptfs page
689  * @from: Ignored (we rotate the page IV on each write)
690  * @to: Ignored
691  *
692  * This is where we encrypt the data and pass the encrypted data to
693  * the lower filesystem.  In OpenPGP-compatible mode, we operate on
694  * entire underlying packets.
695  */
696 static int ecryptfs_commit_write(struct file *file, struct page *page,
697                                  unsigned from, unsigned to)
698 {
699         struct ecryptfs_page_crypt_context ctx;
700         loff_t pos;
701         struct inode *inode;
702         struct inode *lower_inode;
703         struct file *lower_file;
704         struct ecryptfs_crypt_stat *crypt_stat;
705         int rc;
706
707         inode = page->mapping->host;
708         lower_inode = ecryptfs_inode_to_lower(inode);
709         lower_file = ecryptfs_file_to_lower(file);
710         mutex_lock(&lower_inode->i_mutex);
711         crypt_stat = &ecryptfs_inode_to_private(file->f_path.dentry->d_inode)
712                                 ->crypt_stat;
713         if (crypt_stat->flags & ECRYPTFS_NEW_FILE) {
714                 ecryptfs_printk(KERN_DEBUG, "ECRYPTFS_NEW_FILE flag set in "
715                         "crypt_stat at memory location [%p]\n", crypt_stat);
716                 crypt_stat->flags &= ~(ECRYPTFS_NEW_FILE);
717         } else
718                 ecryptfs_printk(KERN_DEBUG, "Not a new file\n");
719         ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
720                         "(page w/ index = [0x%.16x], to = [%d])\n", page->index,
721                         to);
722         rc = fill_zeros_to_end_of_page(page, to);
723         if (rc) {
724                 ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
725                                 "zeros in page with index = [0x%.16x]\n",
726                                 page->index);
727                 goto out;
728         }
729         ctx.page = page;
730         ctx.mode = ECRYPTFS_PREPARE_COMMIT_MODE;
731         ctx.param.lower_file = lower_file;
732         rc = ecryptfs_encrypt_page(&ctx);
733         if (rc) {
734                 ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
735                                 "index [0x%.16x])\n", page->index);
736                 goto out;
737         }
738         inode->i_blocks = lower_inode->i_blocks;
739         pos = (page->index << PAGE_CACHE_SHIFT) + to;
740         if (pos > i_size_read(inode)) {
741                 i_size_write(inode, pos);
742                 ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
743                                 "[0x%.16x]\n", i_size_read(inode));
744         }
745         rc = ecryptfs_write_inode_size_to_metadata(lower_file, lower_inode,
746                                                    inode, file->f_dentry,
747                                                    ECRYPTFS_LOWER_I_MUTEX_HELD);
748         if (rc)
749                 printk(KERN_ERR "Error writing inode size to metadata; "
750                        "rc = [%d]\n", rc);
751         lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
752         mark_inode_dirty_sync(inode);
753 out:
754         if (rc < 0)
755                 ClearPageUptodate(page);
756         else
757                 SetPageUptodate(page);
758         mutex_unlock(&lower_inode->i_mutex);
759         return rc;
760 }
761
762 /**
763  * ecryptfs_write_zeros
764  * @file: The ecryptfs file
765  * @index: The index in which we are writing
766  * @start: The position after the last block of data
767  * @num_zeros: The number of zeros to write
768  *
769  * Write a specified number of zero's to a page.
770  *
771  * (start + num_zeros) must be less than or equal to PAGE_CACHE_SIZE
772  */
773 int
774 ecryptfs_write_zeros(struct file *file, pgoff_t index, int start, int num_zeros)
775 {
776         int rc = 0;
777         struct page *tmp_page;
778
779         tmp_page = ecryptfs_get1page(file, index);
780         if (IS_ERR(tmp_page)) {
781                 ecryptfs_printk(KERN_ERR, "Error getting page at index "
782                                 "[0x%.16x]\n", index);
783                 rc = PTR_ERR(tmp_page);
784                 goto out;
785         }
786         if ((rc = ecryptfs_prepare_write_no_truncate(file, tmp_page, start,
787                                                      (start + num_zeros)))) {
788                 ecryptfs_printk(KERN_ERR, "Error preparing to write zero's "
789                                 "to page at index [0x%.16x]\n",
790                                 index);
791                 page_cache_release(tmp_page);
792                 goto out;
793         }
794         zero_user_page(tmp_page, start, num_zeros, KM_USER0);
795         rc = ecryptfs_commit_write(file, tmp_page, start, start + num_zeros);
796         if (rc < 0) {
797                 ecryptfs_printk(KERN_ERR, "Error attempting to write zero's "
798                                 "to remainder of page at index [0x%.16x]\n",
799                                 index);
800                 page_cache_release(tmp_page);
801                 goto out;
802         }
803         rc = 0;
804         page_cache_release(tmp_page);
805 out:
806         return rc;
807 }
808
809 static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
810 {
811         int rc = 0;
812         struct inode *inode;
813         struct inode *lower_inode;
814
815         inode = (struct inode *)mapping->host;
816         lower_inode = ecryptfs_inode_to_lower(inode);
817         if (lower_inode->i_mapping->a_ops->bmap)
818                 rc = lower_inode->i_mapping->a_ops->bmap(lower_inode->i_mapping,
819                                                          block);
820         return rc;
821 }
822
823 static void ecryptfs_sync_page(struct page *page)
824 {
825         struct inode *inode;
826         struct inode *lower_inode;
827         struct page *lower_page;
828
829         inode = page->mapping->host;
830         lower_inode = ecryptfs_inode_to_lower(inode);
831         /* NOTE: Recently swapped with grab_cache_page(), since
832          * sync_page() just makes sure that pending I/O gets done. */
833         lower_page = find_lock_page(lower_inode->i_mapping, page->index);
834         if (!lower_page) {
835                 ecryptfs_printk(KERN_DEBUG, "find_lock_page failed\n");
836                 return;
837         }
838         lower_page->mapping->a_ops->sync_page(lower_page);
839         ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
840                         lower_page->index);
841         unlock_page(lower_page);
842         page_cache_release(lower_page);
843 }
844
845 struct address_space_operations ecryptfs_aops = {
846         .writepage = ecryptfs_writepage,
847         .readpage = ecryptfs_readpage,
848         .prepare_write = ecryptfs_prepare_write,
849         .commit_write = ecryptfs_commit_write,
850         .bmap = ecryptfs_bmap,
851         .sync_page = ecryptfs_sync_page,
852 };