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[linux-block.git] / fs / ecryptfs / crypto.c
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237fead6
MH		 1/**
2 * eCryptfs: Linux filesystem encryption layer
3 *
4 * Copyright (C) 1997-2004 Erez Zadok
5 * Copyright (C) 2001-2004 Stony Brook University
6 * Copyright (C) 2004-2006 International Business Machines Corp.
7 * Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
8 * Michael C. Thompson <mcthomps@us.ibm.com>
9 *
10 * This program is free software; you can redistribute it and/or
11 * modify it under the terms of the GNU General Public License as
12 * published by the Free Software Foundation; either version 2 of the
13 * License, or (at your option) any later version.
14 *
15 * This program is distributed in the hope that it will be useful, but
16 * WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 * General Public License for more details.
19 *
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
23 * 02111-1307, USA.
24 */
25
26#include <linux/fs.h>
27#include <linux/mount.h>
28#include <linux/pagemap.h>
29#include <linux/random.h>
30#include <linux/compiler.h>
31#include <linux/key.h>
32#include <linux/namei.h>
33#include <linux/crypto.h>
34#include <linux/file.h>
35#include <linux/scatterlist.h>
36#include "ecryptfs_kernel.h"
37
38static int
39ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
40 struct page *dst_page, int dst_offset,
41 struct page *src_page, int src_offset, int size,
42 unsigned char *iv);
43static int
44ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
45 struct page *dst_page, int dst_offset,
46 struct page *src_page, int src_offset, int size,
47 unsigned char *iv);
48
49/**
50 * ecryptfs_to_hex
51 * @dst: Buffer to take hex character representation of contents of
52 * src; must be at least of size (src_size * 2)
53 * @src: Buffer to be converted to a hex string respresentation
54 * @src_size: number of bytes to convert
55 */
56void ecryptfs_to_hex(char *dst, char *src, size_t src_size)
57{
58 int x;
59
60 for (x = 0; x < src_size; x++)
61 sprintf(&dst[x * 2], "%.2x", (unsigned char)src[x]);
62}
63
64/**
65 * ecryptfs_from_hex
66 * @dst: Buffer to take the bytes from src hex; must be at least of
67 * size (src_size / 2)
68 * @src: Buffer to be converted from a hex string respresentation to raw value
69 * @dst_size: size of dst buffer, or number of hex characters pairs to convert
70 */
71void ecryptfs_from_hex(char *dst, char *src, int dst_size)
72{
73 int x;
74 char tmp[3] = { 0, };
75
76 for (x = 0; x < dst_size; x++) {
77 tmp[0] = src[x * 2];
78 tmp[1] = src[x * 2 + 1];
79 dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
80 }
81}
82
83/**
84 * ecryptfs_calculate_md5 - calculates the md5 of @src
85 * @dst: Pointer to 16 bytes of allocated memory
86 * @crypt_stat: Pointer to crypt_stat struct for the current inode
87 * @src: Data to be md5'd
88 * @len: Length of @src
89 *
90 * Uses the allocated crypto context that crypt_stat references to
91 * generate the MD5 sum of the contents of src.
92 */
93static int ecryptfs_calculate_md5(char *dst,
94 struct ecryptfs_crypt_stat *crypt_stat,
95 char *src, int len)
96{
97 int rc = 0;
98 struct scatterlist sg;
99
100 mutex_lock(&crypt_stat->cs_md5_tfm_mutex);
101 sg_init_one(&sg, (u8 *)src, len);
102 if (!crypt_stat->md5_tfm) {
103 crypt_stat->md5_tfm =
104 crypto_alloc_tfm("md5", CRYPTO_TFM_REQ_MAY_SLEEP);
105 if (!crypt_stat->md5_tfm) {
106 rc = -ENOMEM;
107 ecryptfs_printk(KERN_ERR, "Error attempting to "
108 "allocate crypto context\n");
109 goto out;
110 }
111 }
112 crypto_digest_init(crypt_stat->md5_tfm);
113 crypto_digest_update(crypt_stat->md5_tfm, &sg, 1);
114 crypto_digest_final(crypt_stat->md5_tfm, dst);
115 mutex_unlock(&crypt_stat->cs_md5_tfm_mutex);
116out:
117 return rc;
118}
119
120/**
121 * ecryptfs_derive_iv
122 * @iv: destination for the derived iv vale
123 * @crypt_stat: Pointer to crypt_stat struct for the current inode
124 * @offset: Offset of the page whose's iv we are to derive
125 *
126 * Generate the initialization vector from the given root IV and page
127 * offset.
128 *
129 * Returns zero on success; non-zero on error.
130 */
131static int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
132 pgoff_t offset)
133{
134 int rc = 0;
135 char dst[MD5_DIGEST_SIZE];
136 char src[ECRYPTFS_MAX_IV_BYTES + 16];
137
138 if (unlikely(ecryptfs_verbosity > 0)) {
139 ecryptfs_printk(KERN_DEBUG, "root iv:\n");
140 ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes);
141 }
142 /* TODO: It is probably secure to just cast the least
143 * significant bits of the root IV into an unsigned long and
144 * add the offset to that rather than go through all this
145 * hashing business. -Halcrow */
146 memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
147 memset((src + crypt_stat->iv_bytes), 0, 16);
148 snprintf((src + crypt_stat->iv_bytes), 16, "%ld", offset);
149 if (unlikely(ecryptfs_verbosity > 0)) {
150 ecryptfs_printk(KERN_DEBUG, "source:\n");
151 ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
152 }
153 rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
154 (crypt_stat->iv_bytes + 16));
155 if (rc) {
156 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
157 "MD5 while generating IV for a page\n");
158 goto out;
159 }
160 memcpy(iv, dst, crypt_stat->iv_bytes);
161 if (unlikely(ecryptfs_verbosity > 0)) {
162 ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
163 ecryptfs_dump_hex(iv, crypt_stat->iv_bytes);
164 }
165out:
166 return rc;
167}
168
169/**
170 * ecryptfs_init_crypt_stat
171 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
172 *
173 * Initialize the crypt_stat structure.
174 */
175void
176ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
177{
178 memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
179 mutex_init(&crypt_stat->cs_mutex);
180 mutex_init(&crypt_stat->cs_tfm_mutex);
181 mutex_init(&crypt_stat->cs_md5_tfm_mutex);
182 ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_STRUCT_INITIALIZED);
183}
184
185/**
186 * ecryptfs_destruct_crypt_stat
187 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
188 *
189 * Releases all memory associated with a crypt_stat struct.
190 */
191void ecryptfs_destruct_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
192{
193 if (crypt_stat->tfm)
194 crypto_free_tfm(crypt_stat->tfm);
195 if (crypt_stat->md5_tfm)
196 crypto_free_tfm(crypt_stat->md5_tfm);
197 memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
198}
199
200void ecryptfs_destruct_mount_crypt_stat(
201 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
202{
203 if (mount_crypt_stat->global_auth_tok_key)
204 key_put(mount_crypt_stat->global_auth_tok_key);
205 if (mount_crypt_stat->global_key_tfm)
206 crypto_free_tfm(mount_crypt_stat->global_key_tfm);
207 memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
208}
209
210/**
211 * virt_to_scatterlist
212 * @addr: Virtual address
213 * @size: Size of data; should be an even multiple of the block size
214 * @sg: Pointer to scatterlist array; set to NULL to obtain only
215 * the number of scatterlist structs required in array
216 * @sg_size: Max array size
217 *
218 * Fills in a scatterlist array with page references for a passed
219 * virtual address.
220 *
221 * Returns the number of scatterlist structs in array used
222 */
223int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
224 int sg_size)
225{
226 int i = 0;
227 struct page *pg;
228 int offset;
229 int remainder_of_page;
230
231 while (size > 0 && i < sg_size) {
232 pg = virt_to_page(addr);
233 offset = offset_in_page(addr);
234 if (sg) {
235 sg[i].page = pg;
236 sg[i].offset = offset;
237 }
238 remainder_of_page = PAGE_CACHE_SIZE - offset;
239 if (size >= remainder_of_page) {
240 if (sg)
241 sg[i].length = remainder_of_page;
242 addr += remainder_of_page;
243 size -= remainder_of_page;
244 } else {
245 if (sg)
246 sg[i].length = size;
247 addr += size;
248 size = 0;
249 }
250 i++;
251 }
252 if (size > 0)
253 return -ENOMEM;
254 return i;
255}
256
257/**
258 * encrypt_scatterlist
259 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
260 * @dest_sg: Destination of encrypted data
261 * @src_sg: Data to be encrypted
262 * @size: Length of data to be encrypted
263 * @iv: iv to use during encryption
264 *
265 * Returns the number of bytes encrypted; negative value on error
266 */
267static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
268 struct scatterlist *dest_sg,
269 struct scatterlist *src_sg, int size,
270 unsigned char *iv)
271{
272 int rc = 0;
273
274 BUG_ON(!crypt_stat || !crypt_stat->tfm
275 || !ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
276 ECRYPTFS_STRUCT_INITIALIZED));
277 if (unlikely(ecryptfs_verbosity > 0)) {
278 ecryptfs_printk(KERN_DEBUG, "Key size [%d]; key:\n",
279 crypt_stat->key_size);
280 ecryptfs_dump_hex(crypt_stat->key,
281 crypt_stat->key_size);
282 }
283 /* Consider doing this once, when the file is opened */
284 mutex_lock(&crypt_stat->cs_tfm_mutex);
285 rc = crypto_cipher_setkey(crypt_stat->tfm, crypt_stat->key,
286 crypt_stat->key_size);
287 if (rc) {
288 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
289 rc);
290 mutex_unlock(&crypt_stat->cs_tfm_mutex);
291 rc = -EINVAL;
292 goto out;
293 }
294 ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size);
295 crypto_cipher_encrypt_iv(crypt_stat->tfm, dest_sg, src_sg, size, iv);
296 mutex_unlock(&crypt_stat->cs_tfm_mutex);
297out:
298 return rc;
299}
300
301static void
302ecryptfs_extent_to_lwr_pg_idx_and_offset(unsigned long *lower_page_idx,
303 int *byte_offset,
304 struct ecryptfs_crypt_stat *crypt_stat,
305 unsigned long extent_num)
306{
307 unsigned long lower_extent_num;
308 int extents_occupied_by_headers_at_front;
309 int bytes_occupied_by_headers_at_front;
310 int extent_offset;
311 int extents_per_page;
312
313 bytes_occupied_by_headers_at_front =
314 ( crypt_stat->header_extent_size
315 * crypt_stat->num_header_extents_at_front );
316 extents_occupied_by_headers_at_front =
317 ( bytes_occupied_by_headers_at_front
318 / crypt_stat->extent_size );
319 lower_extent_num = extents_occupied_by_headers_at_front + extent_num;
320 extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size;
321 (*lower_page_idx) = lower_extent_num / extents_per_page;
322 extent_offset = lower_extent_num % extents_per_page;
323 (*byte_offset) = extent_offset * crypt_stat->extent_size;
324 ecryptfs_printk(KERN_DEBUG, " * crypt_stat->header_extent_size = "
325 "[%d]\n", crypt_stat->header_extent_size);
326 ecryptfs_printk(KERN_DEBUG, " * crypt_stat->"
327 "num_header_extents_at_front = [%d]\n",
328 crypt_stat->num_header_extents_at_front);
329 ecryptfs_printk(KERN_DEBUG, " * extents_occupied_by_headers_at_"
330 "front = [%d]\n", extents_occupied_by_headers_at_front);
331 ecryptfs_printk(KERN_DEBUG, " * lower_extent_num = [0x%.16x]\n",
332 lower_extent_num);
333 ecryptfs_printk(KERN_DEBUG, " * extents_per_page = [%d]\n",
334 extents_per_page);
335 ecryptfs_printk(KERN_DEBUG, " * (*lower_page_idx) = [0x%.16x]\n",
336 (*lower_page_idx));
337 ecryptfs_printk(KERN_DEBUG, " * extent_offset = [%d]\n",
338 extent_offset);
339 ecryptfs_printk(KERN_DEBUG, " * (*byte_offset) = [%d]\n",
340 (*byte_offset));
341}
342
343static int ecryptfs_write_out_page(struct ecryptfs_page_crypt_context *ctx,
344 struct page *lower_page,
345 struct inode *lower_inode,
346 int byte_offset_in_page, int bytes_to_write)
347{
348 int rc = 0;
349
350 if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) {
351 rc = ecryptfs_commit_lower_page(lower_page, lower_inode,
352 ctx->param.lower_file,
353 byte_offset_in_page,
354 bytes_to_write);
355 if (rc) {
356 ecryptfs_printk(KERN_ERR, "Error calling lower "
357 "commit; rc = [%d]\n", rc);
358 goto out;
359 }
360 } else {
361 rc = ecryptfs_writepage_and_release_lower_page(lower_page,
362 lower_inode,
363 ctx->param.wbc);
364 if (rc) {
365 ecryptfs_printk(KERN_ERR, "Error calling lower "
366 "writepage(); rc = [%d]\n", rc);
367 goto out;
368 }
369 }
370out:
371 return rc;
372}
373
374static int ecryptfs_read_in_page(struct ecryptfs_page_crypt_context *ctx,
375 struct page **lower_page,
376 struct inode *lower_inode,
377 unsigned long lower_page_idx,
378 int byte_offset_in_page)
379{
380 int rc = 0;
381
382 if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) {
383 /* TODO: Limit this to only the data extents that are
384 * needed */
385 rc = ecryptfs_get_lower_page(lower_page, lower_inode,
386 ctx->param.lower_file,
387 lower_page_idx,
388 byte_offset_in_page,
389 (PAGE_CACHE_SIZE
390 - byte_offset_in_page));
391 if (rc) {
392 ecryptfs_printk(
393 KERN_ERR, "Error attempting to grab, map, "
394 "and prepare_write lower page with index "
395 "[0x%.16x]; rc = [%d]\n", lower_page_idx, rc);
396 goto out;
397 }
398 } else {
399 rc = ecryptfs_grab_and_map_lower_page(lower_page, NULL,
400 lower_inode,
401 lower_page_idx);
402 if (rc) {
403 ecryptfs_printk(
404 KERN_ERR, "Error attempting to grab and map "
405 "lower page with index [0x%.16x]; rc = [%d]\n",
406 lower_page_idx, rc);
407 goto out;
408 }
409 }
410out:
411 return rc;
412}
413
414/**
415 * ecryptfs_encrypt_page
416 * @ctx: The context of the page
417 *
418 * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
419 * that eCryptfs pages may straddle the lower pages -- for instance,
420 * if the file was created on a machine with an 8K page size
421 * (resulting in an 8K header), and then the file is copied onto a
422 * host with a 32K page size, then when reading page 0 of the eCryptfs
423 * file, 24K of page 0 of the lower file will be read and decrypted,
424 * and then 8K of page 1 of the lower file will be read and decrypted.
425 *
426 * The actual operations performed on each page depends on the
427 * contents of the ecryptfs_page_crypt_context struct.
428 *
429 * Returns zero on success; negative on error
430 */
431int ecryptfs_encrypt_page(struct ecryptfs_page_crypt_context *ctx)
432{
433 char extent_iv[ECRYPTFS_MAX_IV_BYTES];
434 unsigned long base_extent;
435 unsigned long extent_offset = 0;
436 unsigned long lower_page_idx = 0;
437 unsigned long prior_lower_page_idx = 0;
438 struct page *lower_page;
439 struct inode *lower_inode;
440 struct ecryptfs_inode_info *inode_info;
441 struct ecryptfs_crypt_stat *crypt_stat;
442 int rc = 0;
443 int lower_byte_offset = 0;
444 int orig_byte_offset = 0;
445 int num_extents_per_page;
446#define ECRYPTFS_PAGE_STATE_UNREAD 0
447#define ECRYPTFS_PAGE_STATE_READ 1
448#define ECRYPTFS_PAGE_STATE_MODIFIED 2
449#define ECRYPTFS_PAGE_STATE_WRITTEN 3
450 int page_state;
451
452 lower_inode = ecryptfs_inode_to_lower(ctx->page->mapping->host);
453 inode_info = ecryptfs_inode_to_private(ctx->page->mapping->host);
454 crypt_stat = &inode_info->crypt_stat;
455 if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED)) {
456 rc = ecryptfs_copy_page_to_lower(ctx->page, lower_inode,
457 ctx->param.lower_file);
458 if (rc)
459 ecryptfs_printk(KERN_ERR, "Error attempting to copy "
460 "page at index [0x%.16x]\n",
461 ctx->page->index);
462 goto out;
463 }
464 num_extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size;
465 base_extent = (ctx->page->index * num_extents_per_page);
466 page_state = ECRYPTFS_PAGE_STATE_UNREAD;
467 while (extent_offset < num_extents_per_page) {
468 ecryptfs_extent_to_lwr_pg_idx_and_offset(
469 &lower_page_idx, &lower_byte_offset, crypt_stat,
470 (base_extent + extent_offset));
471 if (prior_lower_page_idx != lower_page_idx
472 && page_state == ECRYPTFS_PAGE_STATE_MODIFIED) {
473 rc = ecryptfs_write_out_page(ctx, lower_page,
474 lower_inode,
475 orig_byte_offset,
476 (PAGE_CACHE_SIZE
477 - orig_byte_offset));
478 if (rc) {
479 ecryptfs_printk(KERN_ERR, "Error attempting "
480 "to write out page; rc = [%d]"
481 "\n", rc);
482 goto out;
483 }
484 page_state = ECRYPTFS_PAGE_STATE_WRITTEN;
485 }
486 if (page_state == ECRYPTFS_PAGE_STATE_UNREAD
487 || page_state == ECRYPTFS_PAGE_STATE_WRITTEN) {
488 rc = ecryptfs_read_in_page(ctx, &lower_page,
489 lower_inode, lower_page_idx,
490 lower_byte_offset);
491 if (rc) {
492 ecryptfs_printk(KERN_ERR, "Error attempting "
493 "to read in lower page with "
494 "index [0x%.16x]; rc = [%d]\n",
495 lower_page_idx, rc);
496 goto out;
497 }
498 orig_byte_offset = lower_byte_offset;
499 prior_lower_page_idx = lower_page_idx;
500 page_state = ECRYPTFS_PAGE_STATE_READ;
501 }
502 BUG_ON(!(page_state == ECRYPTFS_PAGE_STATE_MODIFIED
503 || page_state == ECRYPTFS_PAGE_STATE_READ));
504 rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
505 (base_extent + extent_offset));
506 if (rc) {
507 ecryptfs_printk(KERN_ERR, "Error attempting to "
508 "derive IV for extent [0x%.16x]; "
509 "rc = [%d]\n",
510 (base_extent + extent_offset), rc);
511 goto out;
512 }
513 if (unlikely(ecryptfs_verbosity > 0)) {
514 ecryptfs_printk(KERN_DEBUG, "Encrypting extent "
515 "with iv:\n");
516 ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
517 ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
518 "encryption:\n");
519 ecryptfs_dump_hex((char *)
520 (page_address(ctx->page)
521 + (extent_offset
522 * crypt_stat->extent_size)), 8);
523 }
524 rc = ecryptfs_encrypt_page_offset(
525 crypt_stat, lower_page, lower_byte_offset, ctx->page,
526 (extent_offset * crypt_stat->extent_size),
527 crypt_stat->extent_size, extent_iv);
528 ecryptfs_printk(KERN_DEBUG, "Encrypt extent [0x%.16x]; "
529 "rc = [%d]\n",
530 (base_extent + extent_offset), rc);
531 if (unlikely(ecryptfs_verbosity > 0)) {
532 ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
533 "encryption:\n");
534 ecryptfs_dump_hex((char *)(page_address(lower_page)
535 + lower_byte_offset), 8);
536 }
537 page_state = ECRYPTFS_PAGE_STATE_MODIFIED;
538 extent_offset++;
539 }
540 BUG_ON(orig_byte_offset != 0);
541 rc = ecryptfs_write_out_page(ctx, lower_page, lower_inode, 0,
542 (lower_byte_offset
543 + crypt_stat->extent_size));
544 if (rc) {
545 ecryptfs_printk(KERN_ERR, "Error attempting to write out "
546 "page; rc = [%d]\n", rc);
547 goto out;
548 }
549out:
550 return rc;
551}
552
553/**
554 * ecryptfs_decrypt_page
555 * @file: The ecryptfs file
556 * @page: The page in ecryptfs to decrypt
557 *
558 * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
559 * that eCryptfs pages may straddle the lower pages -- for instance,
560 * if the file was created on a machine with an 8K page size
561 * (resulting in an 8K header), and then the file is copied onto a
562 * host with a 32K page size, then when reading page 0 of the eCryptfs
563 * file, 24K of page 0 of the lower file will be read and decrypted,
564 * and then 8K of page 1 of the lower file will be read and decrypted.
565 *
566 * Returns zero on success; negative on error
567 */
568int ecryptfs_decrypt_page(struct file *file, struct page *page)
569{
570 char extent_iv[ECRYPTFS_MAX_IV_BYTES];
571 unsigned long base_extent;
572 unsigned long extent_offset = 0;
573 unsigned long lower_page_idx = 0;
574 unsigned long prior_lower_page_idx = 0;
575 struct page *lower_page;
576 char *lower_page_virt = NULL;
577 struct inode *lower_inode;
578 struct ecryptfs_crypt_stat *crypt_stat;
579 int rc = 0;
580 int byte_offset;
581 int num_extents_per_page;
582 int page_state;
583
584 crypt_stat = &(ecryptfs_inode_to_private(
585 page->mapping->host)->crypt_stat);
586 lower_inode = ecryptfs_inode_to_lower(page->mapping->host);
587 if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED)) {
588 rc = ecryptfs_do_readpage(file, page, page->index);
589 if (rc)
590 ecryptfs_printk(KERN_ERR, "Error attempting to copy "
591 "page at index [0x%.16x]\n",
592 page->index);
593 goto out;
594 }
595 num_extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size;
596 base_extent = (page->index * num_extents_per_page);
597 lower_page_virt = kmem_cache_alloc(ecryptfs_lower_page_cache,
598 SLAB_KERNEL);
599 if (!lower_page_virt) {
600 rc = -ENOMEM;
601 ecryptfs_printk(KERN_ERR, "Error getting page for encrypted "
602 "lower page(s)\n");
603 goto out;
604 }
605 lower_page = virt_to_page(lower_page_virt);
606 page_state = ECRYPTFS_PAGE_STATE_UNREAD;
607 while (extent_offset < num_extents_per_page) {
608 ecryptfs_extent_to_lwr_pg_idx_and_offset(
609 &lower_page_idx, &byte_offset, crypt_stat,
610 (base_extent + extent_offset));
611 if (prior_lower_page_idx != lower_page_idx
612 || page_state == ECRYPTFS_PAGE_STATE_UNREAD) {
613 rc = ecryptfs_do_readpage(file, lower_page,
614 lower_page_idx);
615 if (rc) {
616 ecryptfs_printk(KERN_ERR, "Error reading "
617 "lower encrypted page; rc = "
618 "[%d]\n", rc);
619 goto out;
620 }
621 prior_lower_page_idx = lower_page_idx;
622 page_state = ECRYPTFS_PAGE_STATE_READ;
623 }
624 rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
625 (base_extent + extent_offset));
626 if (rc) {
627 ecryptfs_printk(KERN_ERR, "Error attempting to "
628 "derive IV for extent [0x%.16x]; rc = "
629 "[%d]\n",
630 (base_extent + extent_offset), rc);
631 goto out;
632 }
633 if (unlikely(ecryptfs_verbosity > 0)) {
634 ecryptfs_printk(KERN_DEBUG, "Decrypting extent "
635 "with iv:\n");
636 ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
637 ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
638 "decryption:\n");
639 ecryptfs_dump_hex((lower_page_virt + byte_offset), 8);
640 }
641 rc = ecryptfs_decrypt_page_offset(crypt_stat, page,
642 (extent_offset
643 * crypt_stat->extent_size),
644 lower_page, byte_offset,
645 crypt_stat->extent_size,
646 extent_iv);
647 if (rc != crypt_stat->extent_size) {
648 ecryptfs_printk(KERN_ERR, "Error attempting to "
649 "decrypt extent [0x%.16x]\n",
650 (base_extent + extent_offset));
651 goto out;
652 }
653 rc = 0;
654 if (unlikely(ecryptfs_verbosity > 0)) {
655 ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
656 "decryption:\n");
657 ecryptfs_dump_hex((char *)(page_address(page)
658 + byte_offset), 8);
659 }
660 extent_offset++;
661 }
662out:
663 if (lower_page_virt)
664 kmem_cache_free(ecryptfs_lower_page_cache, lower_page_virt);
665 return rc;
666}
667
668/**
669 * decrypt_scatterlist
670 *
671 * Returns the number of bytes decrypted; negative value on error
672 */
673static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
674 struct scatterlist *dest_sg,
675 struct scatterlist *src_sg, int size,
676 unsigned char *iv)
677{
678 int rc = 0;
679
680 /* Consider doing this once, when the file is opened */
681 mutex_lock(&crypt_stat->cs_tfm_mutex);
682 rc = crypto_cipher_setkey(crypt_stat->tfm, crypt_stat->key,
683 crypt_stat->key_size);
684 if (rc) {
685 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
686 rc);
687 mutex_unlock(&crypt_stat->cs_tfm_mutex);
688 rc = -EINVAL;
689 goto out;
690 }
691 ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size);
692 rc = crypto_cipher_decrypt_iv(crypt_stat->tfm, dest_sg, src_sg, size,
693 iv);
694 mutex_unlock(&crypt_stat->cs_tfm_mutex);
695 if (rc) {
696 ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n",
697 rc);
698 goto out;
699 }
700 rc = size;
701out:
702 return rc;
703}
704
705/**
706 * ecryptfs_encrypt_page_offset
707 *
708 * Returns the number of bytes encrypted
709 */
710static int
711ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
712 struct page *dst_page, int dst_offset,
713 struct page *src_page, int src_offset, int size,
714 unsigned char *iv)
715{
716 struct scatterlist src_sg, dst_sg;
717
718 src_sg.page = src_page;
719 src_sg.offset = src_offset;
720 src_sg.length = size;
721 dst_sg.page = dst_page;
722 dst_sg.offset = dst_offset;
723 dst_sg.length = size;
724 return encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
725}
726
727/**
728 * ecryptfs_decrypt_page_offset
729 *
730 * Returns the number of bytes decrypted
731 */
732static int
733ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
734 struct page *dst_page, int dst_offset,
735 struct page *src_page, int src_offset, int size,
736 unsigned char *iv)
737{
738 struct scatterlist src_sg, dst_sg;
739
740 src_sg.page = src_page;
741 src_sg.offset = src_offset;
742 src_sg.length = size;
743 dst_sg.page = dst_page;
744 dst_sg.offset = dst_offset;
745 dst_sg.length = size;
746 return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
747}
748
749#define ECRYPTFS_MAX_SCATTERLIST_LEN 4
750
751/**
752 * ecryptfs_init_crypt_ctx
753 * @crypt_stat: Uninitilized crypt stats structure
754 *
755 * Initialize the crypto context.
756 *
757 * TODO: Performance: Keep a cache of initialized cipher contexts;
758 * only init if needed
759 */
760int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
761{
762 int rc = -EINVAL;
763
764 if (!crypt_stat->cipher) {
765 ecryptfs_printk(KERN_ERR, "No cipher specified\n");
766 goto out;
767 }
768 ecryptfs_printk(KERN_DEBUG,
769 "Initializing cipher [%s]; strlen = [%d]; "
770 "key_size_bits = [%d]\n",
771 crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
772 crypt_stat->key_size << 3);
773 if (crypt_stat->tfm) {
774 rc = 0;
775 goto out;
776 }
777 mutex_lock(&crypt_stat->cs_tfm_mutex);
778 crypt_stat->tfm = crypto_alloc_tfm(crypt_stat->cipher,
779 ECRYPTFS_DEFAULT_CHAINING_MODE
780 | CRYPTO_TFM_REQ_WEAK_KEY);
781 mutex_unlock(&crypt_stat->cs_tfm_mutex);
782 if (!crypt_stat->tfm) {
783 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
784 "Error initializing cipher [%s]\n",
785 crypt_stat->cipher);
786 goto out;
787 }
788 rc = 0;
789out:
790 return rc;
791}
792
793static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
794{
795 int extent_size_tmp;
796
797 crypt_stat->extent_mask = 0xFFFFFFFF;
798 crypt_stat->extent_shift = 0;
799 if (crypt_stat->extent_size == 0)
800 return;
801 extent_size_tmp = crypt_stat->extent_size;
802 while ((extent_size_tmp & 0x01) == 0) {
803 extent_size_tmp >>= 1;
804 crypt_stat->extent_mask <<= 1;
805 crypt_stat->extent_shift++;
806 }
807}
808
809void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
810{
811 /* Default values; may be overwritten as we are parsing the
812 * packets. */
813 crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
814 set_extent_mask_and_shift(crypt_stat);
815 crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
816 if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) {
817 crypt_stat->header_extent_size =
818 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
819 } else
820 crypt_stat->header_extent_size = PAGE_CACHE_SIZE;
821 crypt_stat->num_header_extents_at_front = 1;
822}
823
824/**
825 * ecryptfs_compute_root_iv
826 * @crypt_stats
827 *
828 * On error, sets the root IV to all 0's.
829 */
830int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
831{
832 int rc = 0;
833 char dst[MD5_DIGEST_SIZE];
834
835 BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
836 BUG_ON(crypt_stat->iv_bytes <= 0);
837 if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID)) {
838 rc = -EINVAL;
839 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
840 "cannot generate root IV\n");
841 goto out;
842 }
843 rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
844 crypt_stat->key_size);
845 if (rc) {
846 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
847 "MD5 while generating root IV\n");
848 goto out;
849 }
850 memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
851out:
852 if (rc) {
853 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
854 ECRYPTFS_SET_FLAG(crypt_stat->flags,
855 ECRYPTFS_SECURITY_WARNING);
856 }
857 return rc;
858}
859
860static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
861{
862 get_random_bytes(crypt_stat->key, crypt_stat->key_size);
863 ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
864 ecryptfs_compute_root_iv(crypt_stat);
865 if (unlikely(ecryptfs_verbosity > 0)) {
866 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
867 ecryptfs_dump_hex(crypt_stat->key,
868 crypt_stat->key_size);
869 }
870}
871
872/**
873 * ecryptfs_set_default_crypt_stat_vals
874 * @crypt_stat
875 *
876 * Default values in the event that policy does not override them.
877 */
878static void ecryptfs_set_default_crypt_stat_vals(
879 struct ecryptfs_crypt_stat *crypt_stat,
880 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
881{
882 ecryptfs_set_default_sizes(crypt_stat);
883 strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
884 crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
885 ECRYPTFS_CLEAR_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
886 crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
887 crypt_stat->mount_crypt_stat = mount_crypt_stat;
888}
889
890/**
891 * ecryptfs_new_file_context
892 * @ecryptfs_dentry
893 *
894 * If the crypto context for the file has not yet been established,
895 * this is where we do that. Establishing a new crypto context
896 * involves the following decisions:
897 * - What cipher to use?
898 * - What set of authentication tokens to use?
899 * Here we just worry about getting enough information into the
900 * authentication tokens so that we know that they are available.
901 * We associate the available authentication tokens with the new file
902 * via the set of signatures in the crypt_stat struct. Later, when
903 * the headers are actually written out, we may again defer to
904 * userspace to perform the encryption of the session key; for the
905 * foreseeable future, this will be the case with public key packets.
906 *
907 * Returns zero on success; non-zero otherwise
908 */
909/* Associate an authentication token(s) with the file */
910int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry)
911{
912 int rc = 0;
913 struct ecryptfs_crypt_stat *crypt_stat =
914 &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
915 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
916 &ecryptfs_superblock_to_private(
917 ecryptfs_dentry->d_sb)->mount_crypt_stat;
918 int cipher_name_len;
919
920 ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
921 /* See if there are mount crypt options */
922 if (mount_crypt_stat->global_auth_tok) {
923 ecryptfs_printk(KERN_DEBUG, "Initializing context for new "
924 "file using mount_crypt_stat\n");
925 ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED);
926 ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
927 memcpy(crypt_stat->keysigs[crypt_stat->num_keysigs++],
928 mount_crypt_stat->global_auth_tok_sig,
929 ECRYPTFS_SIG_SIZE_HEX);
930 cipher_name_len =
931 strlen(mount_crypt_stat->global_default_cipher_name);
932 memcpy(crypt_stat->cipher,
933 mount_crypt_stat->global_default_cipher_name,
934 cipher_name_len);
935 crypt_stat->cipher[cipher_name_len] = '\0';
936 crypt_stat->key_size =
937 mount_crypt_stat->global_default_cipher_key_size;
938 ecryptfs_generate_new_key(crypt_stat);
939 } else
940 /* We should not encounter this scenario since we
941 * should detect lack of global_auth_tok at mount time
942 * TODO: Applies to 0.1 release only; remove in future
943 * release */
944 BUG();
945 rc = ecryptfs_init_crypt_ctx(crypt_stat);
946 if (rc)
947 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
948 "context for cipher [%s]: rc = [%d]\n",
949 crypt_stat->cipher, rc);
950 return rc;
951}
952
953/**
954 * contains_ecryptfs_marker - check for the ecryptfs marker
955 * @data: The data block in which to check
956 *
957 * Returns one if marker found; zero if not found
958 */
959int contains_ecryptfs_marker(char *data)
960{
961 u32 m_1, m_2;
962
963 memcpy(&m_1, data, 4);
964 m_1 = be32_to_cpu(m_1);
965 memcpy(&m_2, (data + 4), 4);
966 m_2 = be32_to_cpu(m_2);
967 if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
968 return 1;
969 ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
970 "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
971 MAGIC_ECRYPTFS_MARKER);
972 ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
973 "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
974 return 0;
975}
976
977struct ecryptfs_flag_map_elem {
978 u32 file_flag;
979 u32 local_flag;
980};
981
982/* Add support for additional flags by adding elements here. */
983static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
984 {0x00000001, ECRYPTFS_ENABLE_HMAC},
985 {0x00000002, ECRYPTFS_ENCRYPTED}
986};
987
988/**
989 * ecryptfs_process_flags
990 * @crypt_stat
991 * @page_virt: Source data to be parsed
992 * @bytes_read: Updated with the number of bytes read
993 *
994 * Returns zero on success; non-zero if the flag set is invalid
995 */
996static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
997 char *page_virt, int *bytes_read)
998{
999 int rc = 0;
1000 int i;
1001 u32 flags;
1002
1003 memcpy(&flags, page_virt, 4);
1004 flags = be32_to_cpu(flags);
1005 for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1006 / sizeof(struct ecryptfs_flag_map_elem))); i++)
1007 if (flags & ecryptfs_flag_map[i].file_flag) {
1008 ECRYPTFS_SET_FLAG(crypt_stat->flags,
1009 ecryptfs_flag_map[i].local_flag);
1010 } else
1011 ECRYPTFS_CLEAR_FLAG(crypt_stat->flags,
1012 ecryptfs_flag_map[i].local_flag);
1013 /* Version is in top 8 bits of the 32-bit flag vector */
1014 crypt_stat->file_version = ((flags >> 24) & 0xFF);
1015 (*bytes_read) = 4;
1016 return rc;
1017}
1018
1019/**
1020 * write_ecryptfs_marker
1021 * @page_virt: The pointer to in a page to begin writing the marker
1022 * @written: Number of bytes written
1023 *
1024 * Marker = 0x3c81b7f5
1025 */
1026static void write_ecryptfs_marker(char *page_virt, size_t *written)
1027{
1028 u32 m_1, m_2;
1029
1030 get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1031 m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
1032 m_1 = cpu_to_be32(m_1);
1033 memcpy(page_virt, &m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1034 m_2 = cpu_to_be32(m_2);
1035 memcpy(page_virt + (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2), &m_2,
1036 (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1037 (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1038}
1039
1040static void
1041write_ecryptfs_flags(char *page_virt, struct ecryptfs_crypt_stat *crypt_stat,
1042 size_t *written)
1043{
1044 u32 flags = 0;
1045 int i;
1046
1047 for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1048 / sizeof(struct ecryptfs_flag_map_elem))); i++)
1049 if (ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
1050 ecryptfs_flag_map[i].local_flag))
1051 flags |= ecryptfs_flag_map[i].file_flag;
1052 /* Version is in top 8 bits of the 32-bit flag vector */
1053 flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
1054 flags = cpu_to_be32(flags);
1055 memcpy(page_virt, &flags, 4);
1056 (*written) = 4;
1057}
1058
1059struct ecryptfs_cipher_code_str_map_elem {
1060 char cipher_str[16];
1061 u16 cipher_code;
1062};
1063
1064/* Add support for additional ciphers by adding elements here. The
1065 * cipher_code is whatever OpenPGP applicatoins use to identify the
1066 * ciphers. List in order of probability. */
1067static struct ecryptfs_cipher_code_str_map_elem
1068ecryptfs_cipher_code_str_map[] = {
1069 {"aes",RFC2440_CIPHER_AES_128 },
1070 {"blowfish", RFC2440_CIPHER_BLOWFISH},
1071 {"des3_ede", RFC2440_CIPHER_DES3_EDE},
1072 {"cast5", RFC2440_CIPHER_CAST_5},
1073 {"twofish", RFC2440_CIPHER_TWOFISH},
1074 {"cast6", RFC2440_CIPHER_CAST_6},
1075 {"aes", RFC2440_CIPHER_AES_192},
1076 {"aes", RFC2440_CIPHER_AES_256}
1077};
1078
1079/**
1080 * ecryptfs_code_for_cipher_string
1081 * @str: The string representing the cipher name
1082 *
1083 * Returns zero on no match, or the cipher code on match
1084 */
1085u16 ecryptfs_code_for_cipher_string(struct ecryptfs_crypt_stat *crypt_stat)
1086{
1087 int i;
1088 u16 code = 0;
1089 struct ecryptfs_cipher_code_str_map_elem *map =
1090 ecryptfs_cipher_code_str_map;
1091
1092 if (strcmp(crypt_stat->cipher, "aes") == 0) {
1093 switch (crypt_stat->key_size) {
1094 case 16:
1095 code = RFC2440_CIPHER_AES_128;
1096 break;
1097 case 24:
1098 code = RFC2440_CIPHER_AES_192;
1099 break;
1100 case 32:
1101 code = RFC2440_CIPHER_AES_256;
1102 }
1103 } else {
1104 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1105 if (strcmp(crypt_stat->cipher, map[i].cipher_str) == 0){
1106 code = map[i].cipher_code;
1107 break;
1108 }
1109 }
1110 return code;
1111}
1112
1113/**
1114 * ecryptfs_cipher_code_to_string
1115 * @str: Destination to write out the cipher name
1116 * @cipher_code: The code to convert to cipher name string
1117 *
1118 * Returns zero on success
1119 */
1120int ecryptfs_cipher_code_to_string(char *str, u16 cipher_code)
1121{
1122 int rc = 0;
1123 int i;
1124
1125 str[0] = '\0';
1126 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1127 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
1128 strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
1129 if (str[0] == '\0') {
1130 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
1131 "[%d]\n", cipher_code);
1132 rc = -EINVAL;
1133 }
1134 return rc;
1135}
1136
1137/**
1138 * ecryptfs_read_header_region
1139 * @data
1140 * @dentry
1141 * @nd
1142 *
1143 * Returns zero on success; non-zero otherwise
1144 */
1145int ecryptfs_read_header_region(char *data, struct dentry *dentry,
1146 struct vfsmount *mnt)
1147{
1148 struct file *file;
1149 mm_segment_t oldfs;
1150 int rc;
1151
1152 mnt = mntget(mnt);
1153 file = dentry_open(dentry, mnt, O_RDONLY);
1154 if (IS_ERR(file)) {
1155 ecryptfs_printk(KERN_DEBUG, "Error opening file to "
1156 "read header region\n");
1157 mntput(mnt);
1158 rc = PTR_ERR(file);
1159 goto out;
1160 }
1161 file->f_pos = 0;
1162 oldfs = get_fs();
1163 set_fs(get_ds());
1164 /* For releases 0.1 and 0.2, all of the header information
1165 * fits in the first data extent-sized region. */
1166 rc = file->f_op->read(file, (char __user *)data,
1167 ECRYPTFS_DEFAULT_EXTENT_SIZE, &file->f_pos);
1168 set_fs(oldfs);
1169 fput(file);
1170 rc = 0;
1171out:
1172 return rc;
1173}
1174
1175static void
1176write_header_metadata(char *virt, struct ecryptfs_crypt_stat *crypt_stat,
1177 size_t *written)
1178{
1179 u32 header_extent_size;
1180 u16 num_header_extents_at_front;
1181
1182 header_extent_size = (u32)crypt_stat->header_extent_size;
1183 num_header_extents_at_front =
1184 (u16)crypt_stat->num_header_extents_at_front;
1185 header_extent_size = cpu_to_be32(header_extent_size);
1186 memcpy(virt, &header_extent_size, 4);
1187 virt += 4;
1188 num_header_extents_at_front = cpu_to_be16(num_header_extents_at_front);
1189 memcpy(virt, &num_header_extents_at_front, 2);
1190 (*written) = 6;
1191}
1192
1193struct kmem_cache *ecryptfs_header_cache_0;
1194struct kmem_cache *ecryptfs_header_cache_1;
1195struct kmem_cache *ecryptfs_header_cache_2;
1196
1197/**
1198 * ecryptfs_write_headers_virt
1199 * @page_virt
1200 * @crypt_stat
1201 * @ecryptfs_dentry
1202 *
1203 * Format version: 1
1204 *
1205 * Header Extent:
1206 * Octets 0-7: Unencrypted file size (big-endian)
1207 * Octets 8-15: eCryptfs special marker
1208 * Octets 16-19: Flags
1209 * Octet 16: File format version number (between 0 and 255)
1210 * Octets 17-18: Reserved
1211 * Octet 19: Bit 1 (lsb): Reserved
1212 * Bit 2: Encrypted?
1213 * Bits 3-8: Reserved
1214 * Octets 20-23: Header extent size (big-endian)
1215 * Octets 24-25: Number of header extents at front of file
1216 * (big-endian)
1217 * Octet 26: Begin RFC 2440 authentication token packet set
1218 * Data Extent 0:
1219 * Lower data (CBC encrypted)
1220 * Data Extent 1:
1221 * Lower data (CBC encrypted)
1222 * ...
1223 *
1224 * Returns zero on success
1225 */
1226int ecryptfs_write_headers_virt(char *page_virt,
1227 struct ecryptfs_crypt_stat *crypt_stat,
1228 struct dentry *ecryptfs_dentry)
1229{
1230 int rc;
1231 size_t written;
1232 size_t offset;
1233
1234 offset = ECRYPTFS_FILE_SIZE_BYTES;
1235 write_ecryptfs_marker((page_virt + offset), &written);
1236 offset += written;
1237 write_ecryptfs_flags((page_virt + offset), crypt_stat, &written);
1238 offset += written;
1239 write_header_metadata((page_virt + offset), crypt_stat, &written);
1240 offset += written;
1241 rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1242 ecryptfs_dentry, &written,
1243 PAGE_CACHE_SIZE - offset);
1244 if (rc)
1245 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1246 "set; rc = [%d]\n", rc);
1247 return rc;
1248}
1249
1250/**
1251 * ecryptfs_write_headers
1252 * @lower_file: The lower file struct, which was returned from dentry_open
1253 *
1254 * Write the file headers out. This will likely involve a userspace
1255 * callout, in which the session key is encrypted with one or more
1256 * public keys and/or the passphrase necessary to do the encryption is
1257 * retrieved via a prompt. Exactly what happens at this point should
1258 * be policy-dependent.
1259 *
1260 * Returns zero on success; non-zero on error
1261 */
1262int ecryptfs_write_headers(struct dentry *ecryptfs_dentry,
1263 struct file *lower_file)
1264{
1265 mm_segment_t oldfs;
1266 struct ecryptfs_crypt_stat *crypt_stat;
1267 char *page_virt;
1268 int current_header_page;
1269 int header_pages;
1270 int rc = 0;
1271
1272 crypt_stat = &ecryptfs_inode_to_private(
1273 ecryptfs_dentry->d_inode)->crypt_stat;
1274 if (likely(ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
1275 ECRYPTFS_ENCRYPTED))) {
1276 if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
1277 ECRYPTFS_KEY_VALID)) {
1278 ecryptfs_printk(KERN_DEBUG, "Key is "
1279 "invalid; bailing out\n");
1280 rc = -EINVAL;
1281 goto out;
1282 }
1283 } else {
1284 rc = -EINVAL;
1285 ecryptfs_printk(KERN_WARNING,
1286 "Called with crypt_stat->encrypted == 0\n");
1287 goto out;
1288 }
1289 /* Released in this function */
1290 page_virt = kmem_cache_alloc(ecryptfs_header_cache_0, SLAB_USER);
1291 if (!page_virt) {
1292 ecryptfs_printk(KERN_ERR, "Out of memory\n");
1293 rc = -ENOMEM;
1294 goto out;
1295 }
1296 memset(page_virt, 0, PAGE_CACHE_SIZE);
1297 rc = ecryptfs_write_headers_virt(page_virt, crypt_stat,
1298 ecryptfs_dentry);
1299 if (unlikely(rc)) {
1300 ecryptfs_printk(KERN_ERR, "Error whilst writing headers\n");
1301 memset(page_virt, 0, PAGE_CACHE_SIZE);
1302 goto out_free;
1303 }
1304 ecryptfs_printk(KERN_DEBUG,
1305 "Writing key packet set to underlying file\n");
1306 lower_file->f_pos = 0;
1307 oldfs = get_fs();
1308 set_fs(get_ds());
1309 ecryptfs_printk(KERN_DEBUG, "Calling lower_file->f_op->"
1310 "write() w/ header page; lower_file->f_pos = "
1311 "[0x%.16x]\n", lower_file->f_pos);
1312 lower_file->f_op->write(lower_file, (char __user *)page_virt,
1313 PAGE_CACHE_SIZE, &lower_file->f_pos);
1314 header_pages = ((crypt_stat->header_extent_size
1315 * crypt_stat->num_header_extents_at_front)
1316 / PAGE_CACHE_SIZE);
1317 memset(page_virt, 0, PAGE_CACHE_SIZE);
1318 current_header_page = 1;
1319 while (current_header_page < header_pages) {
1320 ecryptfs_printk(KERN_DEBUG, "Calling lower_file->f_op->"
1321 "write() w/ zero'd page; lower_file->f_pos = "
1322 "[0x%.16x]\n", lower_file->f_pos);
1323 lower_file->f_op->write(lower_file, (char __user *)page_virt,
1324 PAGE_CACHE_SIZE, &lower_file->f_pos);
1325 current_header_page++;
1326 }
1327 set_fs(oldfs);
1328 ecryptfs_printk(KERN_DEBUG,
1329 "Done writing key packet set to underlying file.\n");
1330out_free:
1331 kmem_cache_free(ecryptfs_header_cache_0, page_virt);
1332out:
1333 return rc;
1334}
1335
1336static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1337 char *virt, int *bytes_read)
1338{
1339 int rc = 0;
1340 u32 header_extent_size;
1341 u16 num_header_extents_at_front;
1342
1343 memcpy(&header_extent_size, virt, 4);
1344 header_extent_size = be32_to_cpu(header_extent_size);
1345 virt += 4;
1346 memcpy(&num_header_extents_at_front, virt, 2);
1347 num_header_extents_at_front = be16_to_cpu(num_header_extents_at_front);
1348 crypt_stat->header_extent_size = (int)header_extent_size;
1349 crypt_stat->num_header_extents_at_front =
1350 (int)num_header_extents_at_front;
1351 (*bytes_read) = 6;
1352 if ((crypt_stat->header_extent_size
1353 * crypt_stat->num_header_extents_at_front)
1354 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) {
1355 rc = -EINVAL;
1356 ecryptfs_printk(KERN_WARNING, "Invalid header extent size: "
1357 "[%d]\n", crypt_stat->header_extent_size);
1358 }
1359 return rc;
1360}
1361
1362/**
1363 * set_default_header_data
1364 *
1365 * For version 0 file format; this function is only for backwards
1366 * compatibility for files created with the prior versions of
1367 * eCryptfs.
1368 */
1369static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1370{
1371 crypt_stat->header_extent_size = 4096;
1372 crypt_stat->num_header_extents_at_front = 1;
1373}
1374
1375/**
1376 * ecryptfs_read_headers_virt
1377 *
1378 * Read/parse the header data. The header format is detailed in the
1379 * comment block for the ecryptfs_write_headers_virt() function.
1380 *
1381 * Returns zero on success
1382 */
1383static int ecryptfs_read_headers_virt(char *page_virt,
1384 struct ecryptfs_crypt_stat *crypt_stat,
1385 struct dentry *ecryptfs_dentry)
1386{
1387 int rc = 0;
1388 int offset;
1389 int bytes_read;
1390
1391 ecryptfs_set_default_sizes(crypt_stat);
1392 crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1393 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1394 offset = ECRYPTFS_FILE_SIZE_BYTES;
1395 rc = contains_ecryptfs_marker(page_virt + offset);
1396 if (rc == 0) {
1397 rc = -EINVAL;
1398 goto out;
1399 }
1400 offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1401 rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1402 &bytes_read);
1403 if (rc) {
1404 ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1405 goto out;
1406 }
1407 if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1408 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1409 "file version [%d] is supported by this "
1410 "version of eCryptfs\n",
1411 crypt_stat->file_version,
1412 ECRYPTFS_SUPPORTED_FILE_VERSION);
1413 rc = -EINVAL;
1414 goto out;
1415 }
1416 offset += bytes_read;
1417 if (crypt_stat->file_version >= 1) {
1418 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1419 &bytes_read);
1420 if (rc) {
1421 ecryptfs_printk(KERN_WARNING, "Error reading header "
1422 "metadata; rc = [%d]\n", rc);
1423 }
1424 offset += bytes_read;
1425 } else
1426 set_default_header_data(crypt_stat);
1427 rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1428 ecryptfs_dentry);
1429out:
1430 return rc;
1431}
1432
1433/**
1434 * ecryptfs_read_headers
1435 *
1436 * Returns zero if valid headers found and parsed; non-zero otherwise
1437 */
1438int ecryptfs_read_headers(struct dentry *ecryptfs_dentry,
1439 struct file *lower_file)
1440{
1441 int rc = 0;
1442 char *page_virt = NULL;
1443 mm_segment_t oldfs;
1444 ssize_t bytes_read;
1445 struct ecryptfs_crypt_stat *crypt_stat =
1446 &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
1447
1448 /* Read the first page from the underlying file */
1449 page_virt = kmem_cache_alloc(ecryptfs_header_cache_1, SLAB_USER);
1450 if (!page_virt) {
1451 rc = -ENOMEM;
1452 ecryptfs_printk(KERN_ERR, "Unable to allocate page_virt\n");
1453 goto out;
1454 }
1455 lower_file->f_pos = 0;
1456 oldfs = get_fs();
1457 set_fs(get_ds());
1458 bytes_read = lower_file->f_op->read(lower_file,
1459 (char __user *)page_virt,
1460 ECRYPTFS_DEFAULT_EXTENT_SIZE,
1461 &lower_file->f_pos);
1462 set_fs(oldfs);
1463 if (bytes_read != ECRYPTFS_DEFAULT_EXTENT_SIZE) {
1464 rc = -EINVAL;
1465 goto out;
1466 }
1467 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1468 ecryptfs_dentry);
1469 if (rc) {
1470 ecryptfs_printk(KERN_DEBUG, "Valid eCryptfs headers not "
1471 "found\n");
1472 rc = -EINVAL;
1473 }
1474out:
1475 if (page_virt) {
1476 memset(page_virt, 0, PAGE_CACHE_SIZE);
1477 kmem_cache_free(ecryptfs_header_cache_1, page_virt);
1478 }
1479 return rc;
1480}
1481
1482/**
1483 * ecryptfs_encode_filename - converts a plaintext file name to cipher text
1484 * @crypt_stat: The crypt_stat struct associated with the file anem to encode
1485 * @name: The plaintext name
1486 * @length: The length of the plaintext
1487 * @encoded_name: The encypted name
1488 *
1489 * Encrypts and encodes a filename into something that constitutes a
1490 * valid filename for a filesystem, with printable characters.
1491 *
1492 * We assume that we have a properly initialized crypto context,
1493 * pointed to by crypt_stat->tfm.
1494 *
1495 * TODO: Implement filename decoding and decryption here, in place of
1496 * memcpy. We are keeping the framework around for now to (1)
1497 * facilitate testing of the components needed to implement filename
1498 * encryption and (2) to provide a code base from which other
1499 * developers in the community can easily implement this feature.
1500 *
1501 * Returns the length of encoded filename; negative if error
1502 */
1503int
1504ecryptfs_encode_filename(struct ecryptfs_crypt_stat *crypt_stat,
1505 const char *name, int length, char **encoded_name)
1506{
1507 int error = 0;
1508
1509 (*encoded_name) = kmalloc(length + 2, GFP_KERNEL);
1510 if (!(*encoded_name)) {
1511 error = -ENOMEM;
1512 goto out;
1513 }
1514 /* TODO: Filename encryption is a scheduled feature for a
1515 * future version of eCryptfs. This function is here only for
1516 * the purpose of providing a framework for other developers
1517 * to easily implement filename encryption. Hint: Replace this
1518 * memcpy() with a call to encrypt and encode the
1519 * filename, the set the length accordingly. */
1520 memcpy((void *)(*encoded_name), (void *)name, length);
1521 (*encoded_name)[length] = '\0';
1522 error = length + 1;
1523out:
1524 return error;
1525}
1526
1527/**
1528 * ecryptfs_decode_filename - converts the cipher text name to plaintext
1529 * @crypt_stat: The crypt_stat struct associated with the file
1530 * @name: The filename in cipher text
1531 * @length: The length of the cipher text name
1532 * @decrypted_name: The plaintext name
1533 *
1534 * Decodes and decrypts the filename.
1535 *
1536 * We assume that we have a properly initialized crypto context,
1537 * pointed to by crypt_stat->tfm.
1538 *
1539 * TODO: Implement filename decoding and decryption here, in place of
1540 * memcpy. We are keeping the framework around for now to (1)
1541 * facilitate testing of the components needed to implement filename
1542 * encryption and (2) to provide a code base from which other
1543 * developers in the community can easily implement this feature.
1544 *
1545 * Returns the length of decoded filename; negative if error
1546 */
1547int
1548ecryptfs_decode_filename(struct ecryptfs_crypt_stat *crypt_stat,
1549 const char *name, int length, char **decrypted_name)
1550{
1551 int error = 0;
1552
1553 (*decrypted_name) = kmalloc(length + 2, GFP_KERNEL);
1554 if (!(*decrypted_name)) {
1555 error = -ENOMEM;
1556 goto out;
1557 }
1558 /* TODO: Filename encryption is a scheduled feature for a
1559 * future version of eCryptfs. This function is here only for
1560 * the purpose of providing a framework for other developers
1561 * to easily implement filename encryption. Hint: Replace this
1562 * memcpy() with a call to decode and decrypt the
1563 * filename, the set the length accordingly. */
1564 memcpy((void *)(*decrypted_name), (void *)name, length);
1565 (*decrypted_name)[length + 1] = '\0'; /* Only for convenience
1566 * in printing out the
1567 * string in debug
1568 * messages */
1569 error = length;
1570out:
1571 return error;
1572}
1573
1574/**
1575 * ecryptfs_process_cipher - Perform cipher initialization.
1576 * @tfm: Crypto context set by this function
1577 * @key_tfm: Crypto context for key material, set by this function
1578 * @cipher_name: Name of the cipher.
1579 * @key_size: Size of the key in bytes.
1580 *
1581 * Returns zero on success. Any crypto_tfm structs allocated here
1582 * should be released by other functions, such as on a superblock put
1583 * event, regardless of whether this function succeeds for fails.
1584 */
1585int
1586ecryptfs_process_cipher(struct crypto_tfm **tfm, struct crypto_tfm **key_tfm,
1587 char *cipher_name, size_t key_size)
1588{
1589 char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1590 int rc;
1591
1592 *tfm = *key_tfm = NULL;
1593 if (key_size > ECRYPTFS_MAX_KEY_BYTES) {
1594 rc = -EINVAL;
1595 printk(KERN_ERR "Requested key size is [%Zd] bytes; maximum "
1596 "allowable is [%d]\n", key_size, ECRYPTFS_MAX_KEY_BYTES);
1597 goto out;
1598 }
1599 *tfm = crypto_alloc_tfm(cipher_name, (ECRYPTFS_DEFAULT_CHAINING_MODE
1600 | CRYPTO_TFM_REQ_WEAK_KEY));
1601 if (!(*tfm)) {
1602 rc = -EINVAL;
1603 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1604 "[%s]\n", cipher_name);
1605 goto out;
1606 }
1607 *key_tfm = crypto_alloc_tfm(cipher_name, CRYPTO_TFM_REQ_WEAK_KEY);
1608 if (!(*key_tfm)) {
1609 rc = -EINVAL;
1610 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1611 "[%s]\n", cipher_name);
1612 goto out;
1613 }
1614 if (key_size < crypto_tfm_alg_min_keysize(*tfm)) {
1615 rc = -EINVAL;
1616 printk(KERN_ERR "Request key size is [%Zd]; minimum key size "
1617 "supported by cipher [%s] is [%d]\n", key_size,
1618 cipher_name, crypto_tfm_alg_min_keysize(*tfm));
1619 goto out;
1620 }
1621 if (key_size < crypto_tfm_alg_min_keysize(*key_tfm)) {
1622 rc = -EINVAL;
1623 printk(KERN_ERR "Request key size is [%Zd]; minimum key size "
1624 "supported by cipher [%s] is [%d]\n", key_size,
1625 cipher_name, crypto_tfm_alg_min_keysize(*key_tfm));
1626 goto out;
1627 }
1628 if (key_size > crypto_tfm_alg_max_keysize(*tfm)) {
1629 rc = -EINVAL;
1630 printk(KERN_ERR "Request key size is [%Zd]; maximum key size "
1631 "supported by cipher [%s] is [%d]\n", key_size,
1632 cipher_name, crypto_tfm_alg_min_keysize(*tfm));
1633 goto out;
1634 }
1635 if (key_size > crypto_tfm_alg_max_keysize(*key_tfm)) {
1636 rc = -EINVAL;
1637 printk(KERN_ERR "Request key size is [%Zd]; maximum key size "
1638 "supported by cipher [%s] is [%d]\n", key_size,
1639 cipher_name, crypto_tfm_alg_min_keysize(*key_tfm));
1640 goto out;
1641 }
1642 get_random_bytes(dummy_key, key_size);
1643 rc = crypto_cipher_setkey(*tfm, dummy_key, key_size);
1644 if (rc) {
1645 printk(KERN_ERR "Error attempting to set key of size [%Zd] for "
1646 "cipher [%s]; rc = [%d]\n", key_size, cipher_name, rc);
1647 rc = -EINVAL;
1648 goto out;
1649 }
1650 rc = crypto_cipher_setkey(*key_tfm, dummy_key, key_size);
1651 if (rc) {
1652 printk(KERN_ERR "Error attempting to set key of size [%Zd] for "
1653 "cipher [%s]; rc = [%d]\n", key_size, cipher_name, rc);
1654 rc = -EINVAL;
1655 goto out;
1656 }
1657out:
1658 return rc;
1659}
Linux 6.x block layer and io_uring tree(s)