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