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1// SPDX-License-Identifier: GPL-2.0-or-later
2/**
3 * eCryptfs: Linux filesystem encryption layer
4 * This is where eCryptfs coordinates the symmetric encryption and
5 * decryption of the file data as it passes between the lower
6 * encrypted file and the upper decrypted file.
7 *
8 * Copyright (C) 1997-2003 Erez Zadok
9 * Copyright (C) 2001-2003 Stony Brook University
10 * Copyright (C) 2004-2007 International Business Machines Corp.
11 * Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
12 */
13
14#include <linux/pagemap.h>
15#include <linux/writeback.h>
16#include <linux/page-flags.h>
17#include <linux/mount.h>
18#include <linux/file.h>
19#include <linux/scatterlist.h>
20#include <linux/slab.h>
21#include <linux/xattr.h>
22#include <asm/unaligned.h>
23#include "ecryptfs_kernel.h"
24
25/**
26 * ecryptfs_get_locked_page
27 *
28 * Get one page from cache or lower f/s, return error otherwise.
29 *
30 * Returns locked and up-to-date page (if ok), with increased
31 * refcnt.
32 */
33struct page *ecryptfs_get_locked_page(struct inode *inode, loff_t index)
34{
35 struct page *page = read_mapping_page(inode->i_mapping, index, NULL);
36 if (!IS_ERR(page))
37 lock_page(page);
38 return page;
39}
40
41/**
42 * ecryptfs_writepage
43 * @page: Page that is locked before this call is made
44 *
45 * Returns zero on success; non-zero otherwise
46 *
47 * This is where we encrypt the data and pass the encrypted data to
48 * the lower filesystem. In OpenPGP-compatible mode, we operate on
49 * entire underlying packets.
50 */
51static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
52{
53 int rc;
54
55 rc = ecryptfs_encrypt_page(page);
56 if (rc) {
57 ecryptfs_printk(KERN_WARNING, "Error encrypting "
58 "page (upper index [0x%.16lx])\n", page->index);
59 ClearPageUptodate(page);
60 goto out;
61 }
62 SetPageUptodate(page);
63out:
64 unlock_page(page);
65 return rc;
66}
67
68static void strip_xattr_flag(char *page_virt,
69 struct ecryptfs_crypt_stat *crypt_stat)
70{
71 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
72 size_t written;
73
74 crypt_stat->flags &= ~ECRYPTFS_METADATA_IN_XATTR;
75 ecryptfs_write_crypt_stat_flags(page_virt, crypt_stat,
76 &written);
77 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
78 }
79}
80
81/**
82 * Header Extent:
83 * Octets 0-7: Unencrypted file size (big-endian)
84 * Octets 8-15: eCryptfs special marker
85 * Octets 16-19: Flags
86 * Octet 16: File format version number (between 0 and 255)
87 * Octets 17-18: Reserved
88 * Octet 19: Bit 1 (lsb): Reserved
89 * Bit 2: Encrypted?
90 * Bits 3-8: Reserved
91 * Octets 20-23: Header extent size (big-endian)
92 * Octets 24-25: Number of header extents at front of file
93 * (big-endian)
94 * Octet 26: Begin RFC 2440 authentication token packet set
95 */
96
97/**
98 * ecryptfs_copy_up_encrypted_with_header
99 * @page: Sort of a ``virtual'' representation of the encrypted lower
100 * file. The actual lower file does not have the metadata in
101 * the header. This is locked.
102 * @crypt_stat: The eCryptfs inode's cryptographic context
103 *
104 * The ``view'' is the version of the file that userspace winds up
105 * seeing, with the header information inserted.
106 */
107static int
108ecryptfs_copy_up_encrypted_with_header(struct page *page,
109 struct ecryptfs_crypt_stat *crypt_stat)
110{
111 loff_t extent_num_in_page = 0;
112 loff_t num_extents_per_page = (PAGE_SIZE
113 / crypt_stat->extent_size);
114 int rc = 0;
115
116 while (extent_num_in_page < num_extents_per_page) {
117 loff_t view_extent_num = ((((loff_t)page->index)
118 * num_extents_per_page)
119 + extent_num_in_page);
120 size_t num_header_extents_at_front =
121 (crypt_stat->metadata_size / crypt_stat->extent_size);
122
123 if (view_extent_num < num_header_extents_at_front) {
124 /* This is a header extent */
125 char *page_virt;
126
127 page_virt = kmap_atomic(page);
128 memset(page_virt, 0, PAGE_SIZE);
129 /* TODO: Support more than one header extent */
130 if (view_extent_num == 0) {
131 size_t written;
132
133 rc = ecryptfs_read_xattr_region(
134 page_virt, page->mapping->host);
135 strip_xattr_flag(page_virt + 16, crypt_stat);
136 ecryptfs_write_header_metadata(page_virt + 20,
137 crypt_stat,
138 &written);
139 }
140 kunmap_atomic(page_virt);
141 flush_dcache_page(page);
142 if (rc) {
143 printk(KERN_ERR "%s: Error reading xattr "
144 "region; rc = [%d]\n", __func__, rc);
145 goto out;
146 }
147 } else {
148 /* This is an encrypted data extent */
149 loff_t lower_offset =
150 ((view_extent_num * crypt_stat->extent_size)
151 - crypt_stat->metadata_size);
152
153 rc = ecryptfs_read_lower_page_segment(
154 page, (lower_offset >> PAGE_SHIFT),
155 (lower_offset & ~PAGE_MASK),
156 crypt_stat->extent_size, page->mapping->host);
157 if (rc) {
158 printk(KERN_ERR "%s: Error attempting to read "
159 "extent at offset [%lld] in the lower "
160 "file; rc = [%d]\n", __func__,
161 lower_offset, rc);
162 goto out;
163 }
164 }
165 extent_num_in_page++;
166 }
167out:
168 return rc;
169}
170
171/**
172 * ecryptfs_readpage
173 * @file: An eCryptfs file
174 * @page: Page from eCryptfs inode mapping into which to stick the read data
175 *
176 * Read in a page, decrypting if necessary.
177 *
178 * Returns zero on success; non-zero on error.
179 */
180static int ecryptfs_readpage(struct file *file, struct page *page)
181{
182 struct ecryptfs_crypt_stat *crypt_stat =
183 &ecryptfs_inode_to_private(page->mapping->host)->crypt_stat;
184 int rc = 0;
185
186 if (!crypt_stat || !(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
187 rc = ecryptfs_read_lower_page_segment(page, page->index, 0,
188 PAGE_SIZE,
189 page->mapping->host);
190 } else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
191 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
192 rc = ecryptfs_copy_up_encrypted_with_header(page,
193 crypt_stat);
194 if (rc) {
195 printk(KERN_ERR "%s: Error attempting to copy "
196 "the encrypted content from the lower "
197 "file whilst inserting the metadata "
198 "from the xattr into the header; rc = "
199 "[%d]\n", __func__, rc);
200 goto out;
201 }
202
203 } else {
204 rc = ecryptfs_read_lower_page_segment(
205 page, page->index, 0, PAGE_SIZE,
206 page->mapping->host);
207 if (rc) {
208 printk(KERN_ERR "Error reading page; rc = "
209 "[%d]\n", rc);
210 goto out;
211 }
212 }
213 } else {
214 rc = ecryptfs_decrypt_page(page);
215 if (rc) {
216 ecryptfs_printk(KERN_ERR, "Error decrypting page; "
217 "rc = [%d]\n", rc);
218 goto out;
219 }
220 }
221out:
222 if (rc)
223 ClearPageUptodate(page);
224 else
225 SetPageUptodate(page);
226 ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16lx]\n",
227 page->index);
228 unlock_page(page);
229 return rc;
230}
231
232/**
233 * Called with lower inode mutex held.
234 */
235static int fill_zeros_to_end_of_page(struct page *page, unsigned int to)
236{
237 struct inode *inode = page->mapping->host;
238 int end_byte_in_page;
239
240 if ((i_size_read(inode) / PAGE_SIZE) != page->index)
241 goto out;
242 end_byte_in_page = i_size_read(inode) % PAGE_SIZE;
243 if (to > end_byte_in_page)
244 end_byte_in_page = to;
245 zero_user_segment(page, end_byte_in_page, PAGE_SIZE);
246out:
247 return 0;
248}
249
250/**
251 * ecryptfs_write_begin
252 * @file: The eCryptfs file
253 * @mapping: The eCryptfs object
254 * @pos: The file offset at which to start writing
255 * @len: Length of the write
256 * @flags: Various flags
257 * @pagep: Pointer to return the page
258 * @fsdata: Pointer to return fs data (unused)
259 *
260 * This function must zero any hole we create
261 *
262 * Returns zero on success; non-zero otherwise
263 */
264static int ecryptfs_write_begin(struct file *file,
265 struct address_space *mapping,
266 loff_t pos, unsigned len, unsigned flags,
267 struct page **pagep, void **fsdata)
268{
269 pgoff_t index = pos >> PAGE_SHIFT;
270 struct page *page;
271 loff_t prev_page_end_size;
272 int rc = 0;
273
274 page = grab_cache_page_write_begin(mapping, index, flags);
275 if (!page)
276 return -ENOMEM;
277 *pagep = page;
278
279 prev_page_end_size = ((loff_t)index << PAGE_SHIFT);
280 if (!PageUptodate(page)) {
281 struct ecryptfs_crypt_stat *crypt_stat =
282 &ecryptfs_inode_to_private(mapping->host)->crypt_stat;
283
284 if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
285 rc = ecryptfs_read_lower_page_segment(
286 page, index, 0, PAGE_SIZE, mapping->host);
287 if (rc) {
288 printk(KERN_ERR "%s: Error attempting to read "
289 "lower page segment; rc = [%d]\n",
290 __func__, rc);
291 ClearPageUptodate(page);
292 goto out;
293 } else
294 SetPageUptodate(page);
295 } else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
296 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
297 rc = ecryptfs_copy_up_encrypted_with_header(
298 page, crypt_stat);
299 if (rc) {
300 printk(KERN_ERR "%s: Error attempting "
301 "to copy the encrypted content "
302 "from the lower file whilst "
303 "inserting the metadata from "
304 "the xattr into the header; rc "
305 "= [%d]\n", __func__, rc);
306 ClearPageUptodate(page);
307 goto out;
308 }
309 SetPageUptodate(page);
310 } else {
311 rc = ecryptfs_read_lower_page_segment(
312 page, index, 0, PAGE_SIZE,
313 mapping->host);
314 if (rc) {
315 printk(KERN_ERR "%s: Error reading "
316 "page; rc = [%d]\n",
317 __func__, rc);
318 ClearPageUptodate(page);
319 goto out;
320 }
321 SetPageUptodate(page);
322 }
323 } else {
324 if (prev_page_end_size
325 >= i_size_read(page->mapping->host)) {
326 zero_user(page, 0, PAGE_SIZE);
327 SetPageUptodate(page);
328 } else if (len < PAGE_SIZE) {
329 rc = ecryptfs_decrypt_page(page);
330 if (rc) {
331 printk(KERN_ERR "%s: Error decrypting "
332 "page at index [%ld]; "
333 "rc = [%d]\n",
334 __func__, page->index, rc);
335 ClearPageUptodate(page);
336 goto out;
337 }
338 SetPageUptodate(page);
339 }
340 }
341 }
342 /* If creating a page or more of holes, zero them out via truncate.
343 * Note, this will increase i_size. */
344 if (index != 0) {
345 if (prev_page_end_size > i_size_read(page->mapping->host)) {
346 rc = ecryptfs_truncate(file->f_path.dentry,
347 prev_page_end_size);
348 if (rc) {
349 printk(KERN_ERR "%s: Error on attempt to "
350 "truncate to (higher) offset [%lld];"
351 " rc = [%d]\n", __func__,
352 prev_page_end_size, rc);
353 goto out;
354 }
355 }
356 }
357 /* Writing to a new page, and creating a small hole from start
358 * of page? Zero it out. */
359 if ((i_size_read(mapping->host) == prev_page_end_size)
360 && (pos != 0))
361 zero_user(page, 0, PAGE_SIZE);
362out:
363 if (unlikely(rc)) {
364 unlock_page(page);
365 put_page(page);
366 *pagep = NULL;
367 }
368 return rc;
369}
370
371/**
372 * ecryptfs_write_inode_size_to_header
373 *
374 * Writes the lower file size to the first 8 bytes of the header.
375 *
376 * Returns zero on success; non-zero on error.
377 */
378static int ecryptfs_write_inode_size_to_header(struct inode *ecryptfs_inode)
379{
380 char *file_size_virt;
381 int rc;
382
383 file_size_virt = kmalloc(sizeof(u64), GFP_KERNEL);
384 if (!file_size_virt) {
385 rc = -ENOMEM;
386 goto out;
387 }
388 put_unaligned_be64(i_size_read(ecryptfs_inode), file_size_virt);
389 rc = ecryptfs_write_lower(ecryptfs_inode, file_size_virt, 0,
390 sizeof(u64));
391 kfree(file_size_virt);
392 if (rc < 0)
393 printk(KERN_ERR "%s: Error writing file size to header; "
394 "rc = [%d]\n", __func__, rc);
395 else
396 rc = 0;
397out:
398 return rc;
399}
400
401struct kmem_cache *ecryptfs_xattr_cache;
402
403static int ecryptfs_write_inode_size_to_xattr(struct inode *ecryptfs_inode)
404{
405 ssize_t size;
406 void *xattr_virt;
407 struct dentry *lower_dentry =
408 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_path.dentry;
409 struct inode *lower_inode = d_inode(lower_dentry);
410 int rc;
411
412 if (!(lower_inode->i_opflags & IOP_XATTR)) {
413 printk(KERN_WARNING
414 "No support for setting xattr in lower filesystem\n");
415 rc = -ENOSYS;
416 goto out;
417 }
418 xattr_virt = kmem_cache_alloc(ecryptfs_xattr_cache, GFP_KERNEL);
419 if (!xattr_virt) {
420 rc = -ENOMEM;
421 goto out;
422 }
423 inode_lock(lower_inode);
424 size = __vfs_getxattr(lower_dentry, lower_inode, ECRYPTFS_XATTR_NAME,
425 xattr_virt, PAGE_SIZE);
426 if (size < 0)
427 size = 8;
428 put_unaligned_be64(i_size_read(ecryptfs_inode), xattr_virt);
429 rc = __vfs_setxattr(lower_dentry, lower_inode, ECRYPTFS_XATTR_NAME,
430 xattr_virt, size, 0);
431 inode_unlock(lower_inode);
432 if (rc)
433 printk(KERN_ERR "Error whilst attempting to write inode size "
434 "to lower file xattr; rc = [%d]\n", rc);
435 kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
436out:
437 return rc;
438}
439
440int ecryptfs_write_inode_size_to_metadata(struct inode *ecryptfs_inode)
441{
442 struct ecryptfs_crypt_stat *crypt_stat;
443
444 crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
445 BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
446 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
447 return ecryptfs_write_inode_size_to_xattr(ecryptfs_inode);
448 else
449 return ecryptfs_write_inode_size_to_header(ecryptfs_inode);
450}
451
452/**
453 * ecryptfs_write_end
454 * @file: The eCryptfs file object
455 * @mapping: The eCryptfs object
456 * @pos: The file position
457 * @len: The length of the data (unused)
458 * @copied: The amount of data copied
459 * @page: The eCryptfs page
460 * @fsdata: The fsdata (unused)
461 */
462static int ecryptfs_write_end(struct file *file,
463 struct address_space *mapping,
464 loff_t pos, unsigned len, unsigned copied,
465 struct page *page, void *fsdata)
466{
467 pgoff_t index = pos >> PAGE_SHIFT;
468 unsigned from = pos & (PAGE_SIZE - 1);
469 unsigned to = from + copied;
470 struct inode *ecryptfs_inode = mapping->host;
471 struct ecryptfs_crypt_stat *crypt_stat =
472 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
473 int rc;
474
475 ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
476 "(page w/ index = [0x%.16lx], to = [%d])\n", index, to);
477 if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
478 rc = ecryptfs_write_lower_page_segment(ecryptfs_inode, page, 0,
479 to);
480 if (!rc) {
481 rc = copied;
482 fsstack_copy_inode_size(ecryptfs_inode,
483 ecryptfs_inode_to_lower(ecryptfs_inode));
484 }
485 goto out;
486 }
487 if (!PageUptodate(page)) {
488 if (copied < PAGE_SIZE) {
489 rc = 0;
490 goto out;
491 }
492 SetPageUptodate(page);
493 }
494 /* Fills in zeros if 'to' goes beyond inode size */
495 rc = fill_zeros_to_end_of_page(page, to);
496 if (rc) {
497 ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
498 "zeros in page with index = [0x%.16lx]\n", index);
499 goto out;
500 }
501 rc = ecryptfs_encrypt_page(page);
502 if (rc) {
503 ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
504 "index [0x%.16lx])\n", index);
505 goto out;
506 }
507 if (pos + copied > i_size_read(ecryptfs_inode)) {
508 i_size_write(ecryptfs_inode, pos + copied);
509 ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
510 "[0x%.16llx]\n",
511 (unsigned long long)i_size_read(ecryptfs_inode));
512 }
513 rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode);
514 if (rc)
515 printk(KERN_ERR "Error writing inode size to metadata; "
516 "rc = [%d]\n", rc);
517 else
518 rc = copied;
519out:
520 unlock_page(page);
521 put_page(page);
522 return rc;
523}
524
525static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
526{
527 struct inode *lower_inode = ecryptfs_inode_to_lower(mapping->host);
528 int ret = bmap(lower_inode, &block);
529
530 if (ret)
531 return 0;
532 return block;
533}
534
535const struct address_space_operations ecryptfs_aops = {
536 .writepage = ecryptfs_writepage,
537 .readpage = ecryptfs_readpage,
538 .write_begin = ecryptfs_write_begin,
539 .write_end = ecryptfs_write_end,
540 .bmap = ecryptfs_bmap,
541};
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 <linux/slab.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 */
61static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
62{
63 int rc;
64
65 /*
66 * Refuse to write the page out if we are called from reclaim context
67 * since our writepage() path may potentially allocate memory when
68 * calling into the lower fs vfs_write() which may in turn invoke
69 * us again.
70 */
71 if (current->flags & PF_MEMALLOC) {
72 redirty_page_for_writepage(wbc, page);
73 rc = 0;
74 goto out;
75 }
76
77 rc = ecryptfs_encrypt_page(page);
78 if (rc) {
79 ecryptfs_printk(KERN_WARNING, "Error encrypting "
80 "page (upper index [0x%.16lx])\n", page->index);
81 ClearPageUptodate(page);
82 goto out;
83 }
84 SetPageUptodate(page);
85out:
86 unlock_page(page);
87 return rc;
88}
89
90static void strip_xattr_flag(char *page_virt,
91 struct ecryptfs_crypt_stat *crypt_stat)
92{
93 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
94 size_t written;
95
96 crypt_stat->flags &= ~ECRYPTFS_METADATA_IN_XATTR;
97 ecryptfs_write_crypt_stat_flags(page_virt, crypt_stat,
98 &written);
99 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
100 }
101}
102
103/**
104 * Header Extent:
105 * Octets 0-7: Unencrypted file size (big-endian)
106 * Octets 8-15: eCryptfs special marker
107 * Octets 16-19: Flags
108 * Octet 16: File format version number (between 0 and 255)
109 * Octets 17-18: Reserved
110 * Octet 19: Bit 1 (lsb): Reserved
111 * Bit 2: Encrypted?
112 * Bits 3-8: Reserved
113 * Octets 20-23: Header extent size (big-endian)
114 * Octets 24-25: Number of header extents at front of file
115 * (big-endian)
116 * Octet 26: Begin RFC 2440 authentication token packet set
117 */
118
119/**
120 * ecryptfs_copy_up_encrypted_with_header
121 * @page: Sort of a ``virtual'' representation of the encrypted lower
122 * file. The actual lower file does not have the metadata in
123 * the header. This is locked.
124 * @crypt_stat: The eCryptfs inode's cryptographic context
125 *
126 * The ``view'' is the version of the file that userspace winds up
127 * seeing, with the header information inserted.
128 */
129static int
130ecryptfs_copy_up_encrypted_with_header(struct page *page,
131 struct ecryptfs_crypt_stat *crypt_stat)
132{
133 loff_t extent_num_in_page = 0;
134 loff_t num_extents_per_page = (PAGE_CACHE_SIZE
135 / crypt_stat->extent_size);
136 int rc = 0;
137
138 while (extent_num_in_page < num_extents_per_page) {
139 loff_t view_extent_num = ((((loff_t)page->index)
140 * num_extents_per_page)
141 + extent_num_in_page);
142 size_t num_header_extents_at_front =
143 (crypt_stat->metadata_size / crypt_stat->extent_size);
144
145 if (view_extent_num < num_header_extents_at_front) {
146 /* This is a header extent */
147 char *page_virt;
148
149 page_virt = kmap_atomic(page, KM_USER0);
150 memset(page_virt, 0, PAGE_CACHE_SIZE);
151 /* TODO: Support more than one header extent */
152 if (view_extent_num == 0) {
153 size_t written;
154
155 rc = ecryptfs_read_xattr_region(
156 page_virt, page->mapping->host);
157 strip_xattr_flag(page_virt + 16, crypt_stat);
158 ecryptfs_write_header_metadata(page_virt + 20,
159 crypt_stat,
160 &written);
161 }
162 kunmap_atomic(page_virt, KM_USER0);
163 flush_dcache_page(page);
164 if (rc) {
165 printk(KERN_ERR "%s: Error reading xattr "
166 "region; rc = [%d]\n", __func__, rc);
167 goto out;
168 }
169 } else {
170 /* This is an encrypted data extent */
171 loff_t lower_offset =
172 ((view_extent_num * crypt_stat->extent_size)
173 - crypt_stat->metadata_size);
174
175 rc = ecryptfs_read_lower_page_segment(
176 page, (lower_offset >> PAGE_CACHE_SHIFT),
177 (lower_offset & ~PAGE_CACHE_MASK),
178 crypt_stat->extent_size, page->mapping->host);
179 if (rc) {
180 printk(KERN_ERR "%s: Error attempting to read "
181 "extent at offset [%lld] in the lower "
182 "file; rc = [%d]\n", __func__,
183 lower_offset, rc);
184 goto out;
185 }
186 }
187 extent_num_in_page++;
188 }
189out:
190 return rc;
191}
192
193/**
194 * ecryptfs_readpage
195 * @file: An eCryptfs file
196 * @page: Page from eCryptfs inode mapping into which to stick the read data
197 *
198 * Read in a page, decrypting if necessary.
199 *
200 * Returns zero on success; non-zero on error.
201 */
202static int ecryptfs_readpage(struct file *file, struct page *page)
203{
204 struct ecryptfs_crypt_stat *crypt_stat =
205 &ecryptfs_inode_to_private(page->mapping->host)->crypt_stat;
206 int rc = 0;
207
208 if (!crypt_stat || !(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
209 rc = ecryptfs_read_lower_page_segment(page, page->index, 0,
210 PAGE_CACHE_SIZE,
211 page->mapping->host);
212 } else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
213 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
214 rc = ecryptfs_copy_up_encrypted_with_header(page,
215 crypt_stat);
216 if (rc) {
217 printk(KERN_ERR "%s: Error attempting to copy "
218 "the encrypted content from the lower "
219 "file whilst inserting the metadata "
220 "from the xattr into the header; rc = "
221 "[%d]\n", __func__, rc);
222 goto out;
223 }
224
225 } else {
226 rc = ecryptfs_read_lower_page_segment(
227 page, page->index, 0, PAGE_CACHE_SIZE,
228 page->mapping->host);
229 if (rc) {
230 printk(KERN_ERR "Error reading page; rc = "
231 "[%d]\n", rc);
232 goto out;
233 }
234 }
235 } else {
236 rc = ecryptfs_decrypt_page(page);
237 if (rc) {
238 ecryptfs_printk(KERN_ERR, "Error decrypting page; "
239 "rc = [%d]\n", rc);
240 goto out;
241 }
242 }
243out:
244 if (rc)
245 ClearPageUptodate(page);
246 else
247 SetPageUptodate(page);
248 ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16lx]\n",
249 page->index);
250 unlock_page(page);
251 return rc;
252}
253
254/**
255 * Called with lower inode mutex held.
256 */
257static int fill_zeros_to_end_of_page(struct page *page, unsigned int to)
258{
259 struct inode *inode = page->mapping->host;
260 int end_byte_in_page;
261
262 if ((i_size_read(inode) / PAGE_CACHE_SIZE) != page->index)
263 goto out;
264 end_byte_in_page = i_size_read(inode) % PAGE_CACHE_SIZE;
265 if (to > end_byte_in_page)
266 end_byte_in_page = to;
267 zero_user_segment(page, end_byte_in_page, PAGE_CACHE_SIZE);
268out:
269 return 0;
270}
271
272/**
273 * ecryptfs_write_begin
274 * @file: The eCryptfs file
275 * @mapping: The eCryptfs object
276 * @pos: The file offset at which to start writing
277 * @len: Length of the write
278 * @flags: Various flags
279 * @pagep: Pointer to return the page
280 * @fsdata: Pointer to return fs data (unused)
281 *
282 * This function must zero any hole we create
283 *
284 * Returns zero on success; non-zero otherwise
285 */
286static int ecryptfs_write_begin(struct file *file,
287 struct address_space *mapping,
288 loff_t pos, unsigned len, unsigned flags,
289 struct page **pagep, void **fsdata)
290{
291 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
292 struct page *page;
293 loff_t prev_page_end_size;
294 int rc = 0;
295
296 page = grab_cache_page_write_begin(mapping, index, flags);
297 if (!page)
298 return -ENOMEM;
299 *pagep = page;
300
301 prev_page_end_size = ((loff_t)index << PAGE_CACHE_SHIFT);
302 if (!PageUptodate(page)) {
303 struct ecryptfs_crypt_stat *crypt_stat =
304 &ecryptfs_inode_to_private(mapping->host)->crypt_stat;
305
306 if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
307 rc = ecryptfs_read_lower_page_segment(
308 page, index, 0, PAGE_CACHE_SIZE, mapping->host);
309 if (rc) {
310 printk(KERN_ERR "%s: Error attemping to read "
311 "lower page segment; rc = [%d]\n",
312 __func__, rc);
313 ClearPageUptodate(page);
314 goto out;
315 } else
316 SetPageUptodate(page);
317 } else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
318 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
319 rc = ecryptfs_copy_up_encrypted_with_header(
320 page, crypt_stat);
321 if (rc) {
322 printk(KERN_ERR "%s: Error attempting "
323 "to copy the encrypted content "
324 "from the lower file whilst "
325 "inserting the metadata from "
326 "the xattr into the header; rc "
327 "= [%d]\n", __func__, rc);
328 ClearPageUptodate(page);
329 goto out;
330 }
331 SetPageUptodate(page);
332 } else {
333 rc = ecryptfs_read_lower_page_segment(
334 page, index, 0, PAGE_CACHE_SIZE,
335 mapping->host);
336 if (rc) {
337 printk(KERN_ERR "%s: Error reading "
338 "page; rc = [%d]\n",
339 __func__, rc);
340 ClearPageUptodate(page);
341 goto out;
342 }
343 SetPageUptodate(page);
344 }
345 } else {
346 if (prev_page_end_size
347 >= i_size_read(page->mapping->host)) {
348 zero_user(page, 0, PAGE_CACHE_SIZE);
349 } else {
350 rc = ecryptfs_decrypt_page(page);
351 if (rc) {
352 printk(KERN_ERR "%s: Error decrypting "
353 "page at index [%ld]; "
354 "rc = [%d]\n",
355 __func__, page->index, rc);
356 ClearPageUptodate(page);
357 goto out;
358 }
359 }
360 SetPageUptodate(page);
361 }
362 }
363 /* If creating a page or more of holes, zero them out via truncate.
364 * Note, this will increase i_size. */
365 if (index != 0) {
366 if (prev_page_end_size > i_size_read(page->mapping->host)) {
367 rc = ecryptfs_truncate(file->f_path.dentry,
368 prev_page_end_size);
369 if (rc) {
370 printk(KERN_ERR "%s: Error on attempt to "
371 "truncate to (higher) offset [%lld];"
372 " rc = [%d]\n", __func__,
373 prev_page_end_size, rc);
374 goto out;
375 }
376 }
377 }
378 /* Writing to a new page, and creating a small hole from start
379 * of page? Zero it out. */
380 if ((i_size_read(mapping->host) == prev_page_end_size)
381 && (pos != 0))
382 zero_user(page, 0, PAGE_CACHE_SIZE);
383out:
384 if (unlikely(rc)) {
385 unlock_page(page);
386 page_cache_release(page);
387 *pagep = NULL;
388 }
389 return rc;
390}
391
392/**
393 * ecryptfs_write_inode_size_to_header
394 *
395 * Writes the lower file size to the first 8 bytes of the header.
396 *
397 * Returns zero on success; non-zero on error.
398 */
399static int ecryptfs_write_inode_size_to_header(struct inode *ecryptfs_inode)
400{
401 char *file_size_virt;
402 int rc;
403
404 file_size_virt = kmalloc(sizeof(u64), GFP_KERNEL);
405 if (!file_size_virt) {
406 rc = -ENOMEM;
407 goto out;
408 }
409 put_unaligned_be64(i_size_read(ecryptfs_inode), file_size_virt);
410 rc = ecryptfs_write_lower(ecryptfs_inode, file_size_virt, 0,
411 sizeof(u64));
412 kfree(file_size_virt);
413 if (rc < 0)
414 printk(KERN_ERR "%s: Error writing file size to header; "
415 "rc = [%d]\n", __func__, rc);
416 else
417 rc = 0;
418out:
419 return rc;
420}
421
422struct kmem_cache *ecryptfs_xattr_cache;
423
424static int ecryptfs_write_inode_size_to_xattr(struct inode *ecryptfs_inode)
425{
426 ssize_t size;
427 void *xattr_virt;
428 struct dentry *lower_dentry =
429 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_dentry;
430 struct inode *lower_inode = lower_dentry->d_inode;
431 int rc;
432
433 if (!lower_inode->i_op->getxattr || !lower_inode->i_op->setxattr) {
434 printk(KERN_WARNING
435 "No support for setting xattr in lower filesystem\n");
436 rc = -ENOSYS;
437 goto out;
438 }
439 xattr_virt = kmem_cache_alloc(ecryptfs_xattr_cache, GFP_KERNEL);
440 if (!xattr_virt) {
441 printk(KERN_ERR "Out of memory whilst attempting to write "
442 "inode size to xattr\n");
443 rc = -ENOMEM;
444 goto out;
445 }
446 mutex_lock(&lower_inode->i_mutex);
447 size = lower_inode->i_op->getxattr(lower_dentry, ECRYPTFS_XATTR_NAME,
448 xattr_virt, PAGE_CACHE_SIZE);
449 if (size < 0)
450 size = 8;
451 put_unaligned_be64(i_size_read(ecryptfs_inode), xattr_virt);
452 rc = lower_inode->i_op->setxattr(lower_dentry, ECRYPTFS_XATTR_NAME,
453 xattr_virt, size, 0);
454 mutex_unlock(&lower_inode->i_mutex);
455 if (rc)
456 printk(KERN_ERR "Error whilst attempting to write inode size "
457 "to lower file xattr; rc = [%d]\n", rc);
458 kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
459out:
460 return rc;
461}
462
463int ecryptfs_write_inode_size_to_metadata(struct inode *ecryptfs_inode)
464{
465 struct ecryptfs_crypt_stat *crypt_stat;
466
467 crypt_stat = &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
468 BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
469 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
470 return ecryptfs_write_inode_size_to_xattr(ecryptfs_inode);
471 else
472 return ecryptfs_write_inode_size_to_header(ecryptfs_inode);
473}
474
475/**
476 * ecryptfs_write_end
477 * @file: The eCryptfs file object
478 * @mapping: The eCryptfs object
479 * @pos: The file position
480 * @len: The length of the data (unused)
481 * @copied: The amount of data copied
482 * @page: The eCryptfs page
483 * @fsdata: The fsdata (unused)
484 *
485 * This is where we encrypt the data and pass the encrypted data to
486 * the lower filesystem. In OpenPGP-compatible mode, we operate on
487 * entire underlying packets.
488 */
489static int ecryptfs_write_end(struct file *file,
490 struct address_space *mapping,
491 loff_t pos, unsigned len, unsigned copied,
492 struct page *page, void *fsdata)
493{
494 pgoff_t index = pos >> PAGE_CACHE_SHIFT;
495 unsigned from = pos & (PAGE_CACHE_SIZE - 1);
496 unsigned to = from + copied;
497 struct inode *ecryptfs_inode = mapping->host;
498 struct ecryptfs_crypt_stat *crypt_stat =
499 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
500 int rc;
501 int need_unlock_page = 1;
502
503 ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
504 "(page w/ index = [0x%.16lx], to = [%d])\n", index, to);
505 if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
506 rc = ecryptfs_write_lower_page_segment(ecryptfs_inode, page, 0,
507 to);
508 if (!rc) {
509 rc = copied;
510 fsstack_copy_inode_size(ecryptfs_inode,
511 ecryptfs_inode_to_lower(ecryptfs_inode));
512 }
513 goto out;
514 }
515 /* Fills in zeros if 'to' goes beyond inode size */
516 rc = fill_zeros_to_end_of_page(page, to);
517 if (rc) {
518 ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
519 "zeros in page with index = [0x%.16lx]\n", index);
520 goto out;
521 }
522 set_page_dirty(page);
523 unlock_page(page);
524 need_unlock_page = 0;
525 if (pos + copied > i_size_read(ecryptfs_inode)) {
526 i_size_write(ecryptfs_inode, pos + copied);
527 ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
528 "[0x%.16llx]\n",
529 (unsigned long long)i_size_read(ecryptfs_inode));
530 balance_dirty_pages_ratelimited(mapping);
531 rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode);
532 if (rc) {
533 printk(KERN_ERR "Error writing inode size to metadata; "
534 "rc = [%d]\n", rc);
535 goto out;
536 }
537 }
538 rc = copied;
539out:
540 if (need_unlock_page)
541 unlock_page(page);
542 page_cache_release(page);
543 return rc;
544}
545
546static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
547{
548 int rc = 0;
549 struct inode *inode;
550 struct inode *lower_inode;
551
552 inode = (struct inode *)mapping->host;
553 lower_inode = ecryptfs_inode_to_lower(inode);
554 if (lower_inode->i_mapping->a_ops->bmap)
555 rc = lower_inode->i_mapping->a_ops->bmap(lower_inode->i_mapping,
556 block);
557 return rc;
558}
559
560const struct address_space_operations ecryptfs_aops = {
561 .writepage = ecryptfs_writepage,
562 .readpage = ecryptfs_readpage,
563 .write_begin = ecryptfs_write_begin,
564 .write_end = ecryptfs_write_end,
565 .bmap = ecryptfs_bmap,
566};