Loading...
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/scatterlist.h>
34#include <linux/slab.h>
35#include <asm/unaligned.h>
36#include "ecryptfs_kernel.h"
37
38/**
39 * ecryptfs_get_locked_page
40 *
41 * Get one page from cache or lower f/s, return error otherwise.
42 *
43 * Returns locked and up-to-date page (if ok), with increased
44 * refcnt.
45 */
46struct page *ecryptfs_get_locked_page(struct inode *inode, loff_t index)
47{
48 struct page *page = read_mapping_page(inode->i_mapping, index, NULL);
49 if (!IS_ERR(page))
50 lock_page(page);
51 return page;
52}
53
54/**
55 * ecryptfs_writepage
56 * @page: Page that is locked before this call is made
57 *
58 * Returns zero on success; non-zero otherwise
59 *
60 * This is where we encrypt the data and pass the encrypted data to
61 * the lower filesystem. In OpenPGP-compatible mode, we operate on
62 * entire underlying packets.
63 */
64static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
65{
66 int rc;
67
68 rc = ecryptfs_encrypt_page(page);
69 if (rc) {
70 ecryptfs_printk(KERN_WARNING, "Error encrypting "
71 "page (upper index [0x%.16lx])\n", page->index);
72 ClearPageUptodate(page);
73 goto out;
74 }
75 SetPageUptodate(page);
76out:
77 unlock_page(page);
78 return rc;
79}
80
81static void strip_xattr_flag(char *page_virt,
82 struct ecryptfs_crypt_stat *crypt_stat)
83{
84 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
85 size_t written;
86
87 crypt_stat->flags &= ~ECRYPTFS_METADATA_IN_XATTR;
88 ecryptfs_write_crypt_stat_flags(page_virt, crypt_stat,
89 &written);
90 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
91 }
92}
93
94/**
95 * Header Extent:
96 * Octets 0-7: Unencrypted file size (big-endian)
97 * Octets 8-15: eCryptfs special marker
98 * Octets 16-19: Flags
99 * Octet 16: File format version number (between 0 and 255)
100 * Octets 17-18: Reserved
101 * Octet 19: Bit 1 (lsb): Reserved
102 * Bit 2: Encrypted?
103 * Bits 3-8: Reserved
104 * Octets 20-23: Header extent size (big-endian)
105 * Octets 24-25: Number of header extents at front of file
106 * (big-endian)
107 * Octet 26: Begin RFC 2440 authentication token packet set
108 */
109
110/**
111 * ecryptfs_copy_up_encrypted_with_header
112 * @page: Sort of a ``virtual'' representation of the encrypted lower
113 * file. The actual lower file does not have the metadata in
114 * the header. This is locked.
115 * @crypt_stat: The eCryptfs inode's cryptographic context
116 *
117 * The ``view'' is the version of the file that userspace winds up
118 * seeing, with the header information inserted.
119 */
120static int
121ecryptfs_copy_up_encrypted_with_header(struct page *page,
122 struct ecryptfs_crypt_stat *crypt_stat)
123{
124 loff_t extent_num_in_page = 0;
125 loff_t num_extents_per_page = (PAGE_SIZE
126 / crypt_stat->extent_size);
127 int rc = 0;
128
129 while (extent_num_in_page < num_extents_per_page) {
130 loff_t view_extent_num = ((((loff_t)page->index)
131 * num_extents_per_page)
132 + extent_num_in_page);
133 size_t num_header_extents_at_front =
134 (crypt_stat->metadata_size / crypt_stat->extent_size);
135
136 if (view_extent_num < num_header_extents_at_front) {
137 /* This is a header extent */
138 char *page_virt;
139
140 page_virt = kmap_atomic(page);
141 memset(page_virt, 0, PAGE_SIZE);
142 /* TODO: Support more than one header extent */
143 if (view_extent_num == 0) {
144 size_t written;
145
146 rc = ecryptfs_read_xattr_region(
147 page_virt, page->mapping->host);
148 strip_xattr_flag(page_virt + 16, crypt_stat);
149 ecryptfs_write_header_metadata(page_virt + 20,
150 crypt_stat,
151 &written);
152 }
153 kunmap_atomic(page_virt);
154 flush_dcache_page(page);
155 if (rc) {
156 printk(KERN_ERR "%s: Error reading xattr "
157 "region; rc = [%d]\n", __func__, rc);
158 goto out;
159 }
160 } else {
161 /* This is an encrypted data extent */
162 loff_t lower_offset =
163 ((view_extent_num * crypt_stat->extent_size)
164 - crypt_stat->metadata_size);
165
166 rc = ecryptfs_read_lower_page_segment(
167 page, (lower_offset >> PAGE_SHIFT),
168 (lower_offset & ~PAGE_MASK),
169 crypt_stat->extent_size, page->mapping->host);
170 if (rc) {
171 printk(KERN_ERR "%s: Error attempting to read "
172 "extent at offset [%lld] in the lower "
173 "file; rc = [%d]\n", __func__,
174 lower_offset, rc);
175 goto out;
176 }
177 }
178 extent_num_in_page++;
179 }
180out:
181 return rc;
182}
183
184/**
185 * ecryptfs_readpage
186 * @file: An eCryptfs file
187 * @page: Page from eCryptfs inode mapping into which to stick the read data
188 *
189 * Read in a page, decrypting if necessary.
190 *
191 * Returns zero on success; non-zero on error.
192 */
193static int ecryptfs_readpage(struct file *file, struct page *page)
194{
195 struct ecryptfs_crypt_stat *crypt_stat =
196 &ecryptfs_inode_to_private(page->mapping->host)->crypt_stat;
197 int rc = 0;
198
199 if (!crypt_stat || !(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
200 rc = ecryptfs_read_lower_page_segment(page, page->index, 0,
201 PAGE_SIZE,
202 page->mapping->host);
203 } else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
204 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
205 rc = ecryptfs_copy_up_encrypted_with_header(page,
206 crypt_stat);
207 if (rc) {
208 printk(KERN_ERR "%s: Error attempting to copy "
209 "the encrypted content from the lower "
210 "file whilst inserting the metadata "
211 "from the xattr into the header; rc = "
212 "[%d]\n", __func__, rc);
213 goto out;
214 }
215
216 } else {
217 rc = ecryptfs_read_lower_page_segment(
218 page, page->index, 0, PAGE_SIZE,
219 page->mapping->host);
220 if (rc) {
221 printk(KERN_ERR "Error reading page; rc = "
222 "[%d]\n", rc);
223 goto out;
224 }
225 }
226 } else {
227 rc = ecryptfs_decrypt_page(page);
228 if (rc) {
229 ecryptfs_printk(KERN_ERR, "Error decrypting page; "
230 "rc = [%d]\n", rc);
231 goto out;
232 }
233 }
234out:
235 if (rc)
236 ClearPageUptodate(page);
237 else
238 SetPageUptodate(page);
239 ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16lx]\n",
240 page->index);
241 unlock_page(page);
242 return rc;
243}
244
245/**
246 * Called with lower inode mutex held.
247 */
248static int fill_zeros_to_end_of_page(struct page *page, unsigned int to)
249{
250 struct inode *inode = page->mapping->host;
251 int end_byte_in_page;
252
253 if ((i_size_read(inode) / PAGE_SIZE) != page->index)
254 goto out;
255 end_byte_in_page = i_size_read(inode) % PAGE_SIZE;
256 if (to > end_byte_in_page)
257 end_byte_in_page = to;
258 zero_user_segment(page, end_byte_in_page, PAGE_SIZE);
259out:
260 return 0;
261}
262
263/**
264 * ecryptfs_write_begin
265 * @file: The eCryptfs file
266 * @mapping: The eCryptfs object
267 * @pos: The file offset at which to start writing
268 * @len: Length of the write
269 * @flags: Various flags
270 * @pagep: Pointer to return the page
271 * @fsdata: Pointer to return fs data (unused)
272 *
273 * This function must zero any hole we create
274 *
275 * Returns zero on success; non-zero otherwise
276 */
277static int ecryptfs_write_begin(struct file *file,
278 struct address_space *mapping,
279 loff_t pos, unsigned len, unsigned flags,
280 struct page **pagep, void **fsdata)
281{
282 pgoff_t index = pos >> PAGE_SHIFT;
283 struct page *page;
284 loff_t prev_page_end_size;
285 int rc = 0;
286
287 page = grab_cache_page_write_begin(mapping, index, flags);
288 if (!page)
289 return -ENOMEM;
290 *pagep = page;
291
292 prev_page_end_size = ((loff_t)index << PAGE_SHIFT);
293 if (!PageUptodate(page)) {
294 struct ecryptfs_crypt_stat *crypt_stat =
295 &ecryptfs_inode_to_private(mapping->host)->crypt_stat;
296
297 if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
298 rc = ecryptfs_read_lower_page_segment(
299 page, index, 0, PAGE_SIZE, mapping->host);
300 if (rc) {
301 printk(KERN_ERR "%s: Error attempting to read "
302 "lower page segment; rc = [%d]\n",
303 __func__, rc);
304 ClearPageUptodate(page);
305 goto out;
306 } else
307 SetPageUptodate(page);
308 } else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
309 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
310 rc = ecryptfs_copy_up_encrypted_with_header(
311 page, crypt_stat);
312 if (rc) {
313 printk(KERN_ERR "%s: Error attempting "
314 "to copy the encrypted content "
315 "from the lower file whilst "
316 "inserting the metadata from "
317 "the xattr into the header; rc "
318 "= [%d]\n", __func__, rc);
319 ClearPageUptodate(page);
320 goto out;
321 }
322 SetPageUptodate(page);
323 } else {
324 rc = ecryptfs_read_lower_page_segment(
325 page, index, 0, PAGE_SIZE,
326 mapping->host);
327 if (rc) {
328 printk(KERN_ERR "%s: Error reading "
329 "page; rc = [%d]\n",
330 __func__, rc);
331 ClearPageUptodate(page);
332 goto out;
333 }
334 SetPageUptodate(page);
335 }
336 } else {
337 if (prev_page_end_size
338 >= i_size_read(page->mapping->host)) {
339 zero_user(page, 0, PAGE_SIZE);
340 SetPageUptodate(page);
341 } else if (len < PAGE_SIZE) {
342 rc = ecryptfs_decrypt_page(page);
343 if (rc) {
344 printk(KERN_ERR "%s: Error decrypting "
345 "page at index [%ld]; "
346 "rc = [%d]\n",
347 __func__, page->index, rc);
348 ClearPageUptodate(page);
349 goto out;
350 }
351 SetPageUptodate(page);
352 }
353 }
354 }
355 /* If creating a page or more of holes, zero them out via truncate.
356 * Note, this will increase i_size. */
357 if (index != 0) {
358 if (prev_page_end_size > i_size_read(page->mapping->host)) {
359 rc = ecryptfs_truncate(file->f_path.dentry,
360 prev_page_end_size);
361 if (rc) {
362 printk(KERN_ERR "%s: Error on attempt to "
363 "truncate to (higher) offset [%lld];"
364 " rc = [%d]\n", __func__,
365 prev_page_end_size, rc);
366 goto out;
367 }
368 }
369 }
370 /* Writing to a new page, and creating a small hole from start
371 * of page? Zero it out. */
372 if ((i_size_read(mapping->host) == prev_page_end_size)
373 && (pos != 0))
374 zero_user(page, 0, PAGE_SIZE);
375out:
376 if (unlikely(rc)) {
377 unlock_page(page);
378 put_page(page);
379 *pagep = NULL;
380 }
381 return rc;
382}
383
384/**
385 * ecryptfs_write_inode_size_to_header
386 *
387 * Writes the lower file size to the first 8 bytes of the header.
388 *
389 * Returns zero on success; non-zero on error.
390 */
391static int ecryptfs_write_inode_size_to_header(struct inode *ecryptfs_inode)
392{
393 char *file_size_virt;
394 int rc;
395
396 file_size_virt = kmalloc(sizeof(u64), GFP_KERNEL);
397 if (!file_size_virt) {
398 rc = -ENOMEM;
399 goto out;
400 }
401 put_unaligned_be64(i_size_read(ecryptfs_inode), file_size_virt);
402 rc = ecryptfs_write_lower(ecryptfs_inode, file_size_virt, 0,
403 sizeof(u64));
404 kfree(file_size_virt);
405 if (rc < 0)
406 printk(KERN_ERR "%s: Error writing file size to header; "
407 "rc = [%d]\n", __func__, rc);
408 else
409 rc = 0;
410out:
411 return rc;
412}
413
414struct kmem_cache *ecryptfs_xattr_cache;
415
416static int ecryptfs_write_inode_size_to_xattr(struct inode *ecryptfs_inode)
417{
418 ssize_t size;
419 void *xattr_virt;
420 struct dentry *lower_dentry =
421 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_path.dentry;
422 struct inode *lower_inode = d_inode(lower_dentry);
423 int rc;
424
425 if (!lower_inode->i_op->getxattr || !lower_inode->i_op->setxattr) {
426 printk(KERN_WARNING
427 "No support for setting xattr in lower filesystem\n");
428 rc = -ENOSYS;
429 goto out;
430 }
431 xattr_virt = kmem_cache_alloc(ecryptfs_xattr_cache, GFP_KERNEL);
432 if (!xattr_virt) {
433 printk(KERN_ERR "Out of memory whilst attempting to write "
434 "inode size to xattr\n");
435 rc = -ENOMEM;
436 goto out;
437 }
438 inode_lock(lower_inode);
439 size = lower_inode->i_op->getxattr(lower_dentry, ECRYPTFS_XATTR_NAME,
440 xattr_virt, PAGE_SIZE);
441 if (size < 0)
442 size = 8;
443 put_unaligned_be64(i_size_read(ecryptfs_inode), xattr_virt);
444 rc = lower_inode->i_op->setxattr(lower_dentry, ECRYPTFS_XATTR_NAME,
445 xattr_virt, size, 0);
446 inode_unlock(lower_inode);
447 if (rc)
448 printk(KERN_ERR "Error whilst attempting to write inode size "
449 "to lower file xattr; rc = [%d]\n", rc);
450 kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
451out:
452 return rc;
453}
454
455int ecryptfs_write_inode_size_to_metadata(struct inode *ecryptfs_inode)
456{
457 struct ecryptfs_crypt_stat *crypt_stat;
458
459 crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
460 BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
461 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
462 return ecryptfs_write_inode_size_to_xattr(ecryptfs_inode);
463 else
464 return ecryptfs_write_inode_size_to_header(ecryptfs_inode);
465}
466
467/**
468 * ecryptfs_write_end
469 * @file: The eCryptfs file object
470 * @mapping: The eCryptfs object
471 * @pos: The file position
472 * @len: The length of the data (unused)
473 * @copied: The amount of data copied
474 * @page: The eCryptfs page
475 * @fsdata: The fsdata (unused)
476 */
477static int ecryptfs_write_end(struct file *file,
478 struct address_space *mapping,
479 loff_t pos, unsigned len, unsigned copied,
480 struct page *page, void *fsdata)
481{
482 pgoff_t index = pos >> PAGE_SHIFT;
483 unsigned from = pos & (PAGE_SIZE - 1);
484 unsigned to = from + copied;
485 struct inode *ecryptfs_inode = mapping->host;
486 struct ecryptfs_crypt_stat *crypt_stat =
487 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
488 int rc;
489
490 ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
491 "(page w/ index = [0x%.16lx], to = [%d])\n", index, to);
492 if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
493 rc = ecryptfs_write_lower_page_segment(ecryptfs_inode, page, 0,
494 to);
495 if (!rc) {
496 rc = copied;
497 fsstack_copy_inode_size(ecryptfs_inode,
498 ecryptfs_inode_to_lower(ecryptfs_inode));
499 }
500 goto out;
501 }
502 if (!PageUptodate(page)) {
503 if (copied < PAGE_SIZE) {
504 rc = 0;
505 goto out;
506 }
507 SetPageUptodate(page);
508 }
509 /* Fills in zeros if 'to' goes beyond inode size */
510 rc = fill_zeros_to_end_of_page(page, to);
511 if (rc) {
512 ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
513 "zeros in page with index = [0x%.16lx]\n", index);
514 goto out;
515 }
516 rc = ecryptfs_encrypt_page(page);
517 if (rc) {
518 ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
519 "index [0x%.16lx])\n", index);
520 goto out;
521 }
522 if (pos + copied > i_size_read(ecryptfs_inode)) {
523 i_size_write(ecryptfs_inode, pos + copied);
524 ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
525 "[0x%.16llx]\n",
526 (unsigned long long)i_size_read(ecryptfs_inode));
527 }
528 rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode);
529 if (rc)
530 printk(KERN_ERR "Error writing inode size to metadata; "
531 "rc = [%d]\n", rc);
532 else
533 rc = copied;
534out:
535 unlock_page(page);
536 put_page(page);
537 return rc;
538}
539
540static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
541{
542 int rc = 0;
543 struct inode *inode;
544 struct inode *lower_inode;
545
546 inode = (struct inode *)mapping->host;
547 lower_inode = ecryptfs_inode_to_lower(inode);
548 if (lower_inode->i_mapping->a_ops->bmap)
549 rc = lower_inode->i_mapping->a_ops->bmap(lower_inode->i_mapping,
550 block);
551 return rc;
552}
553
554const struct address_space_operations ecryptfs_aops = {
555 .writepage = ecryptfs_writepage,
556 .readpage = ecryptfs_readpage,
557 .write_begin = ecryptfs_write_begin,
558 .write_end = ecryptfs_write_end,
559 .bmap = ecryptfs_bmap,
560};
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/scatterlist.h>
34#include <linux/slab.h>
35#include <linux/xattr.h>
36#include <asm/unaligned.h>
37#include "ecryptfs_kernel.h"
38
39/**
40 * ecryptfs_get_locked_page
41 *
42 * Get one page from cache or lower f/s, return error otherwise.
43 *
44 * Returns locked and up-to-date page (if ok), with increased
45 * refcnt.
46 */
47struct page *ecryptfs_get_locked_page(struct inode *inode, loff_t index)
48{
49 struct page *page = read_mapping_page(inode->i_mapping, index, NULL);
50 if (!IS_ERR(page))
51 lock_page(page);
52 return page;
53}
54
55/**
56 * ecryptfs_writepage
57 * @page: Page that is locked before this call is made
58 *
59 * Returns zero on success; non-zero otherwise
60 *
61 * This is where we encrypt the data and pass the encrypted data to
62 * the lower filesystem. In OpenPGP-compatible mode, we operate on
63 * entire underlying packets.
64 */
65static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
66{
67 int rc;
68
69 rc = ecryptfs_encrypt_page(page);
70 if (rc) {
71 ecryptfs_printk(KERN_WARNING, "Error encrypting "
72 "page (upper index [0x%.16lx])\n", page->index);
73 ClearPageUptodate(page);
74 goto out;
75 }
76 SetPageUptodate(page);
77out:
78 unlock_page(page);
79 return rc;
80}
81
82static void strip_xattr_flag(char *page_virt,
83 struct ecryptfs_crypt_stat *crypt_stat)
84{
85 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
86 size_t written;
87
88 crypt_stat->flags &= ~ECRYPTFS_METADATA_IN_XATTR;
89 ecryptfs_write_crypt_stat_flags(page_virt, crypt_stat,
90 &written);
91 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
92 }
93}
94
95/**
96 * Header Extent:
97 * Octets 0-7: Unencrypted file size (big-endian)
98 * Octets 8-15: eCryptfs special marker
99 * Octets 16-19: Flags
100 * Octet 16: File format version number (between 0 and 255)
101 * Octets 17-18: Reserved
102 * Octet 19: Bit 1 (lsb): Reserved
103 * Bit 2: Encrypted?
104 * Bits 3-8: Reserved
105 * Octets 20-23: Header extent size (big-endian)
106 * Octets 24-25: Number of header extents at front of file
107 * (big-endian)
108 * Octet 26: Begin RFC 2440 authentication token packet set
109 */
110
111/**
112 * ecryptfs_copy_up_encrypted_with_header
113 * @page: Sort of a ``virtual'' representation of the encrypted lower
114 * file. The actual lower file does not have the metadata in
115 * the header. This is locked.
116 * @crypt_stat: The eCryptfs inode's cryptographic context
117 *
118 * The ``view'' is the version of the file that userspace winds up
119 * seeing, with the header information inserted.
120 */
121static int
122ecryptfs_copy_up_encrypted_with_header(struct page *page,
123 struct ecryptfs_crypt_stat *crypt_stat)
124{
125 loff_t extent_num_in_page = 0;
126 loff_t num_extents_per_page = (PAGE_SIZE
127 / crypt_stat->extent_size);
128 int rc = 0;
129
130 while (extent_num_in_page < num_extents_per_page) {
131 loff_t view_extent_num = ((((loff_t)page->index)
132 * num_extents_per_page)
133 + extent_num_in_page);
134 size_t num_header_extents_at_front =
135 (crypt_stat->metadata_size / crypt_stat->extent_size);
136
137 if (view_extent_num < num_header_extents_at_front) {
138 /* This is a header extent */
139 char *page_virt;
140
141 page_virt = kmap_atomic(page);
142 memset(page_virt, 0, PAGE_SIZE);
143 /* TODO: Support more than one header extent */
144 if (view_extent_num == 0) {
145 size_t written;
146
147 rc = ecryptfs_read_xattr_region(
148 page_virt, page->mapping->host);
149 strip_xattr_flag(page_virt + 16, crypt_stat);
150 ecryptfs_write_header_metadata(page_virt + 20,
151 crypt_stat,
152 &written);
153 }
154 kunmap_atomic(page_virt);
155 flush_dcache_page(page);
156 if (rc) {
157 printk(KERN_ERR "%s: Error reading xattr "
158 "region; rc = [%d]\n", __func__, rc);
159 goto out;
160 }
161 } else {
162 /* This is an encrypted data extent */
163 loff_t lower_offset =
164 ((view_extent_num * crypt_stat->extent_size)
165 - crypt_stat->metadata_size);
166
167 rc = ecryptfs_read_lower_page_segment(
168 page, (lower_offset >> PAGE_SHIFT),
169 (lower_offset & ~PAGE_MASK),
170 crypt_stat->extent_size, page->mapping->host);
171 if (rc) {
172 printk(KERN_ERR "%s: Error attempting to read "
173 "extent at offset [%lld] in the lower "
174 "file; rc = [%d]\n", __func__,
175 lower_offset, rc);
176 goto out;
177 }
178 }
179 extent_num_in_page++;
180 }
181out:
182 return rc;
183}
184
185/**
186 * ecryptfs_readpage
187 * @file: An eCryptfs file
188 * @page: Page from eCryptfs inode mapping into which to stick the read data
189 *
190 * Read in a page, decrypting if necessary.
191 *
192 * Returns zero on success; non-zero on error.
193 */
194static int ecryptfs_readpage(struct file *file, struct page *page)
195{
196 struct ecryptfs_crypt_stat *crypt_stat =
197 &ecryptfs_inode_to_private(page->mapping->host)->crypt_stat;
198 int rc = 0;
199
200 if (!crypt_stat || !(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
201 rc = ecryptfs_read_lower_page_segment(page, page->index, 0,
202 PAGE_SIZE,
203 page->mapping->host);
204 } else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
205 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
206 rc = ecryptfs_copy_up_encrypted_with_header(page,
207 crypt_stat);
208 if (rc) {
209 printk(KERN_ERR "%s: Error attempting to copy "
210 "the encrypted content from the lower "
211 "file whilst inserting the metadata "
212 "from the xattr into the header; rc = "
213 "[%d]\n", __func__, rc);
214 goto out;
215 }
216
217 } else {
218 rc = ecryptfs_read_lower_page_segment(
219 page, page->index, 0, PAGE_SIZE,
220 page->mapping->host);
221 if (rc) {
222 printk(KERN_ERR "Error reading page; rc = "
223 "[%d]\n", rc);
224 goto out;
225 }
226 }
227 } else {
228 rc = ecryptfs_decrypt_page(page);
229 if (rc) {
230 ecryptfs_printk(KERN_ERR, "Error decrypting page; "
231 "rc = [%d]\n", rc);
232 goto out;
233 }
234 }
235out:
236 if (rc)
237 ClearPageUptodate(page);
238 else
239 SetPageUptodate(page);
240 ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16lx]\n",
241 page->index);
242 unlock_page(page);
243 return rc;
244}
245
246/**
247 * Called with lower inode mutex held.
248 */
249static int fill_zeros_to_end_of_page(struct page *page, unsigned int to)
250{
251 struct inode *inode = page->mapping->host;
252 int end_byte_in_page;
253
254 if ((i_size_read(inode) / PAGE_SIZE) != page->index)
255 goto out;
256 end_byte_in_page = i_size_read(inode) % PAGE_SIZE;
257 if (to > end_byte_in_page)
258 end_byte_in_page = to;
259 zero_user_segment(page, end_byte_in_page, PAGE_SIZE);
260out:
261 return 0;
262}
263
264/**
265 * ecryptfs_write_begin
266 * @file: The eCryptfs file
267 * @mapping: The eCryptfs object
268 * @pos: The file offset at which to start writing
269 * @len: Length of the write
270 * @flags: Various flags
271 * @pagep: Pointer to return the page
272 * @fsdata: Pointer to return fs data (unused)
273 *
274 * This function must zero any hole we create
275 *
276 * Returns zero on success; non-zero otherwise
277 */
278static int ecryptfs_write_begin(struct file *file,
279 struct address_space *mapping,
280 loff_t pos, unsigned len, unsigned flags,
281 struct page **pagep, void **fsdata)
282{
283 pgoff_t index = pos >> PAGE_SHIFT;
284 struct page *page;
285 loff_t prev_page_end_size;
286 int rc = 0;
287
288 page = grab_cache_page_write_begin(mapping, index, flags);
289 if (!page)
290 return -ENOMEM;
291 *pagep = page;
292
293 prev_page_end_size = ((loff_t)index << PAGE_SHIFT);
294 if (!PageUptodate(page)) {
295 struct ecryptfs_crypt_stat *crypt_stat =
296 &ecryptfs_inode_to_private(mapping->host)->crypt_stat;
297
298 if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
299 rc = ecryptfs_read_lower_page_segment(
300 page, index, 0, PAGE_SIZE, mapping->host);
301 if (rc) {
302 printk(KERN_ERR "%s: Error attempting to read "
303 "lower page segment; rc = [%d]\n",
304 __func__, rc);
305 ClearPageUptodate(page);
306 goto out;
307 } else
308 SetPageUptodate(page);
309 } else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
310 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
311 rc = ecryptfs_copy_up_encrypted_with_header(
312 page, crypt_stat);
313 if (rc) {
314 printk(KERN_ERR "%s: Error attempting "
315 "to copy the encrypted content "
316 "from the lower file whilst "
317 "inserting the metadata from "
318 "the xattr into the header; rc "
319 "= [%d]\n", __func__, rc);
320 ClearPageUptodate(page);
321 goto out;
322 }
323 SetPageUptodate(page);
324 } else {
325 rc = ecryptfs_read_lower_page_segment(
326 page, index, 0, PAGE_SIZE,
327 mapping->host);
328 if (rc) {
329 printk(KERN_ERR "%s: Error reading "
330 "page; rc = [%d]\n",
331 __func__, rc);
332 ClearPageUptodate(page);
333 goto out;
334 }
335 SetPageUptodate(page);
336 }
337 } else {
338 if (prev_page_end_size
339 >= i_size_read(page->mapping->host)) {
340 zero_user(page, 0, PAGE_SIZE);
341 SetPageUptodate(page);
342 } else if (len < PAGE_SIZE) {
343 rc = ecryptfs_decrypt_page(page);
344 if (rc) {
345 printk(KERN_ERR "%s: Error decrypting "
346 "page at index [%ld]; "
347 "rc = [%d]\n",
348 __func__, page->index, rc);
349 ClearPageUptodate(page);
350 goto out;
351 }
352 SetPageUptodate(page);
353 }
354 }
355 }
356 /* If creating a page or more of holes, zero them out via truncate.
357 * Note, this will increase i_size. */
358 if (index != 0) {
359 if (prev_page_end_size > i_size_read(page->mapping->host)) {
360 rc = ecryptfs_truncate(file->f_path.dentry,
361 prev_page_end_size);
362 if (rc) {
363 printk(KERN_ERR "%s: Error on attempt to "
364 "truncate to (higher) offset [%lld];"
365 " rc = [%d]\n", __func__,
366 prev_page_end_size, rc);
367 goto out;
368 }
369 }
370 }
371 /* Writing to a new page, and creating a small hole from start
372 * of page? Zero it out. */
373 if ((i_size_read(mapping->host) == prev_page_end_size)
374 && (pos != 0))
375 zero_user(page, 0, PAGE_SIZE);
376out:
377 if (unlikely(rc)) {
378 unlock_page(page);
379 put_page(page);
380 *pagep = NULL;
381 }
382 return rc;
383}
384
385/**
386 * ecryptfs_write_inode_size_to_header
387 *
388 * Writes the lower file size to the first 8 bytes of the header.
389 *
390 * Returns zero on success; non-zero on error.
391 */
392static int ecryptfs_write_inode_size_to_header(struct inode *ecryptfs_inode)
393{
394 char *file_size_virt;
395 int rc;
396
397 file_size_virt = kmalloc(sizeof(u64), GFP_KERNEL);
398 if (!file_size_virt) {
399 rc = -ENOMEM;
400 goto out;
401 }
402 put_unaligned_be64(i_size_read(ecryptfs_inode), file_size_virt);
403 rc = ecryptfs_write_lower(ecryptfs_inode, file_size_virt, 0,
404 sizeof(u64));
405 kfree(file_size_virt);
406 if (rc < 0)
407 printk(KERN_ERR "%s: Error writing file size to header; "
408 "rc = [%d]\n", __func__, rc);
409 else
410 rc = 0;
411out:
412 return rc;
413}
414
415struct kmem_cache *ecryptfs_xattr_cache;
416
417static int ecryptfs_write_inode_size_to_xattr(struct inode *ecryptfs_inode)
418{
419 ssize_t size;
420 void *xattr_virt;
421 struct dentry *lower_dentry =
422 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_path.dentry;
423 struct inode *lower_inode = d_inode(lower_dentry);
424 int rc;
425
426 if (!(lower_inode->i_opflags & IOP_XATTR)) {
427 printk(KERN_WARNING
428 "No support for setting xattr in lower filesystem\n");
429 rc = -ENOSYS;
430 goto out;
431 }
432 xattr_virt = kmem_cache_alloc(ecryptfs_xattr_cache, GFP_KERNEL);
433 if (!xattr_virt) {
434 rc = -ENOMEM;
435 goto out;
436 }
437 inode_lock(lower_inode);
438 size = __vfs_getxattr(lower_dentry, lower_inode, ECRYPTFS_XATTR_NAME,
439 xattr_virt, PAGE_SIZE);
440 if (size < 0)
441 size = 8;
442 put_unaligned_be64(i_size_read(ecryptfs_inode), xattr_virt);
443 rc = __vfs_setxattr(lower_dentry, lower_inode, ECRYPTFS_XATTR_NAME,
444 xattr_virt, size, 0);
445 inode_unlock(lower_inode);
446 if (rc)
447 printk(KERN_ERR "Error whilst attempting to write inode size "
448 "to lower file xattr; rc = [%d]\n", rc);
449 kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
450out:
451 return rc;
452}
453
454int ecryptfs_write_inode_size_to_metadata(struct inode *ecryptfs_inode)
455{
456 struct ecryptfs_crypt_stat *crypt_stat;
457
458 crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
459 BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
460 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
461 return ecryptfs_write_inode_size_to_xattr(ecryptfs_inode);
462 else
463 return ecryptfs_write_inode_size_to_header(ecryptfs_inode);
464}
465
466/**
467 * ecryptfs_write_end
468 * @file: The eCryptfs file object
469 * @mapping: The eCryptfs object
470 * @pos: The file position
471 * @len: The length of the data (unused)
472 * @copied: The amount of data copied
473 * @page: The eCryptfs page
474 * @fsdata: The fsdata (unused)
475 */
476static int ecryptfs_write_end(struct file *file,
477 struct address_space *mapping,
478 loff_t pos, unsigned len, unsigned copied,
479 struct page *page, void *fsdata)
480{
481 pgoff_t index = pos >> PAGE_SHIFT;
482 unsigned from = pos & (PAGE_SIZE - 1);
483 unsigned to = from + copied;
484 struct inode *ecryptfs_inode = mapping->host;
485 struct ecryptfs_crypt_stat *crypt_stat =
486 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
487 int rc;
488
489 ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
490 "(page w/ index = [0x%.16lx], to = [%d])\n", index, to);
491 if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
492 rc = ecryptfs_write_lower_page_segment(ecryptfs_inode, page, 0,
493 to);
494 if (!rc) {
495 rc = copied;
496 fsstack_copy_inode_size(ecryptfs_inode,
497 ecryptfs_inode_to_lower(ecryptfs_inode));
498 }
499 goto out;
500 }
501 if (!PageUptodate(page)) {
502 if (copied < PAGE_SIZE) {
503 rc = 0;
504 goto out;
505 }
506 SetPageUptodate(page);
507 }
508 /* Fills in zeros if 'to' goes beyond inode size */
509 rc = fill_zeros_to_end_of_page(page, to);
510 if (rc) {
511 ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
512 "zeros in page with index = [0x%.16lx]\n", index);
513 goto out;
514 }
515 rc = ecryptfs_encrypt_page(page);
516 if (rc) {
517 ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
518 "index [0x%.16lx])\n", index);
519 goto out;
520 }
521 if (pos + copied > i_size_read(ecryptfs_inode)) {
522 i_size_write(ecryptfs_inode, pos + copied);
523 ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
524 "[0x%.16llx]\n",
525 (unsigned long long)i_size_read(ecryptfs_inode));
526 }
527 rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode);
528 if (rc)
529 printk(KERN_ERR "Error writing inode size to metadata; "
530 "rc = [%d]\n", rc);
531 else
532 rc = copied;
533out:
534 unlock_page(page);
535 put_page(page);
536 return rc;
537}
538
539static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
540{
541 int rc = 0;
542 struct inode *inode;
543 struct inode *lower_inode;
544
545 inode = (struct inode *)mapping->host;
546 lower_inode = ecryptfs_inode_to_lower(inode);
547 if (lower_inode->i_mapping->a_ops->bmap)
548 rc = lower_inode->i_mapping->a_ops->bmap(lower_inode->i_mapping,
549 block);
550 return rc;
551}
552
553const struct address_space_operations ecryptfs_aops = {
554 .writepage = ecryptfs_writepage,
555 .readpage = ecryptfs_readpage,
556 .write_begin = ecryptfs_write_begin,
557 .write_end = ecryptfs_write_end,
558 .bmap = ecryptfs_bmap,
559};