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