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Merge branch 'upstream-linus' of master.kernel.org:/pub/scm/linux/kernel/git/jgarzik...
[linux-2.6-block.git] / fs / ecryptfs / crypto.c
CommitLineData
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{
237fead6 97 struct scatterlist sg;
565d9724
MH		 98 struct hash_desc desc = {
99 .tfm = crypt_stat->hash_tfm,
100 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
101 };
102 int rc = 0;
237fead6 103
565d9724 104 mutex_lock(&crypt_stat->cs_hash_tfm_mutex);
237fead6 105 sg_init_one(&sg, (u8 *)src, len);
565d9724
MH		 106 if (!desc.tfm) {
107 desc.tfm = crypto_alloc_hash(ECRYPTFS_DEFAULT_HASH, 0,
108 CRYPTO_ALG_ASYNC);
109 if (IS_ERR(desc.tfm)) {
110 rc = PTR_ERR(desc.tfm);
237fead6 111 ecryptfs_printk(KERN_ERR, "Error attempting to "
565d9724
MH		 112 "allocate crypto context; rc = [%d]\n",
113 rc);
237fead6
MH		 114 goto out;
115 }
565d9724 116 crypt_stat->hash_tfm = desc.tfm;
237fead6 117 }
565d9724
MH		 118 crypto_hash_init(&desc);
119 crypto_hash_update(&desc, &sg, len);
120 crypto_hash_final(&desc, dst);
121 mutex_unlock(&crypt_stat->cs_hash_tfm_mutex);
237fead6
MH		 122out:
123 return rc;
124}
125
8bba066f
MH		 126int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
127 char *cipher_name,
128 char *chaining_modifier)
129{
130 int cipher_name_len = strlen(cipher_name);
131 int chaining_modifier_len = strlen(chaining_modifier);
132 int algified_name_len;
133 int rc;
134
135 algified_name_len = (chaining_modifier_len + cipher_name_len + 3);
136 (*algified_name) = kmalloc(algified_name_len, GFP_KERNEL);
137 if (!(algified_name)) {
138 rc = -ENOMEM;
139 goto out;
140 }
141 snprintf((*algified_name), algified_name_len, "%s(%s)",
142 chaining_modifier, cipher_name);
143 rc = 0;
144out:
145 return rc;
146}
147
237fead6
MH		 148/**
149 * ecryptfs_derive_iv
150 * @iv: destination for the derived iv vale
151 * @crypt_stat: Pointer to crypt_stat struct for the current inode
152 * @offset: Offset of the page whose's iv we are to derive
153 *
154 * Generate the initialization vector from the given root IV and page
155 * offset.
156 *
157 * Returns zero on success; non-zero on error.
158 */
159static int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
160 pgoff_t offset)
161{
162 int rc = 0;
163 char dst[MD5_DIGEST_SIZE];
164 char src[ECRYPTFS_MAX_IV_BYTES + 16];
165
166 if (unlikely(ecryptfs_verbosity > 0)) {
167 ecryptfs_printk(KERN_DEBUG, "root iv:\n");
168 ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes);
169 }
170 /* TODO: It is probably secure to just cast the least
171 * significant bits of the root IV into an unsigned long and
172 * add the offset to that rather than go through all this
173 * hashing business. -Halcrow */
174 memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
175 memset((src + crypt_stat->iv_bytes), 0, 16);
176 snprintf((src + crypt_stat->iv_bytes), 16, "%ld", offset);
177 if (unlikely(ecryptfs_verbosity > 0)) {
178 ecryptfs_printk(KERN_DEBUG, "source:\n");
179 ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
180 }
181 rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
182 (crypt_stat->iv_bytes + 16));
183 if (rc) {
184 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
185 "MD5 while generating IV for a page\n");
186 goto out;
187 }
188 memcpy(iv, dst, crypt_stat->iv_bytes);
189 if (unlikely(ecryptfs_verbosity > 0)) {
190 ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
191 ecryptfs_dump_hex(iv, crypt_stat->iv_bytes);
192 }
193out:
194 return rc;
195}
196
197/**
198 * ecryptfs_init_crypt_stat
199 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
200 *
201 * Initialize the crypt_stat structure.
202 */
203void
204ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
205{
206 memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
207 mutex_init(&crypt_stat->cs_mutex);
208 mutex_init(&crypt_stat->cs_tfm_mutex);
565d9724 209 mutex_init(&crypt_stat->cs_hash_tfm_mutex);
237fead6
MH		 210 ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_STRUCT_INITIALIZED);
211}
212
213/**
214 * ecryptfs_destruct_crypt_stat
215 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
216 *
217 * Releases all memory associated with a crypt_stat struct.
218 */
219void ecryptfs_destruct_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
220{
221 if (crypt_stat->tfm)
8bba066f 222 crypto_free_blkcipher(crypt_stat->tfm);
565d9724
MH		 223 if (crypt_stat->hash_tfm)
224 crypto_free_hash(crypt_stat->hash_tfm);
237fead6
MH		 225 memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
226}
227
228void ecryptfs_destruct_mount_crypt_stat(
229 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
230{
231 if (mount_crypt_stat->global_auth_tok_key)
232 key_put(mount_crypt_stat->global_auth_tok_key);
233 if (mount_crypt_stat->global_key_tfm)
8bba066f 234 crypto_free_blkcipher(mount_crypt_stat->global_key_tfm);
237fead6
MH		 235 memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
236}
237
238/**
239 * virt_to_scatterlist
240 * @addr: Virtual address
241 * @size: Size of data; should be an even multiple of the block size
242 * @sg: Pointer to scatterlist array; set to NULL to obtain only
243 * the number of scatterlist structs required in array
244 * @sg_size: Max array size
245 *
246 * Fills in a scatterlist array with page references for a passed
247 * virtual address.
248 *
249 * Returns the number of scatterlist structs in array used
250 */
251int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
252 int sg_size)
253{
254 int i = 0;
255 struct page *pg;
256 int offset;
257 int remainder_of_page;
258
259 while (size > 0 && i < sg_size) {
260 pg = virt_to_page(addr);
261 offset = offset_in_page(addr);
262 if (sg) {
263 sg[i].page = pg;
264 sg[i].offset = offset;
265 }
266 remainder_of_page = PAGE_CACHE_SIZE - offset;
267 if (size >= remainder_of_page) {
268 if (sg)
269 sg[i].length = remainder_of_page;
270 addr += remainder_of_page;
271 size -= remainder_of_page;
272 } else {
273 if (sg)
274 sg[i].length = size;
275 addr += size;
276 size = 0;
277 }
278 i++;
279 }
280 if (size > 0)
281 return -ENOMEM;
282 return i;
283}
284
285/**
286 * encrypt_scatterlist
287 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
288 * @dest_sg: Destination of encrypted data
289 * @src_sg: Data to be encrypted
290 * @size: Length of data to be encrypted
291 * @iv: iv to use during encryption
292 *
293 * Returns the number of bytes encrypted; negative value on error
294 */
295static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
296 struct scatterlist *dest_sg,
297 struct scatterlist *src_sg, int size,
298 unsigned char *iv)
299{
8bba066f
MH		 300 struct blkcipher_desc desc = {
301 .tfm = crypt_stat->tfm,
302 .info = iv,
303 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
304 };
237fead6
MH		 305 int rc = 0;
306
307 BUG_ON(!crypt_stat || !crypt_stat->tfm
308 || !ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
309 ECRYPTFS_STRUCT_INITIALIZED));
310 if (unlikely(ecryptfs_verbosity > 0)) {
311 ecryptfs_printk(KERN_DEBUG, "Key size [%d]; key:\n",
312 crypt_stat->key_size);
313 ecryptfs_dump_hex(crypt_stat->key,
314 crypt_stat->key_size);
315 }
316 /* Consider doing this once, when the file is opened */
317 mutex_lock(&crypt_stat->cs_tfm_mutex);
8bba066f
MH		 318 rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
319 crypt_stat->key_size);
237fead6
MH		 320 if (rc) {
321 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
322 rc);
323 mutex_unlock(&crypt_stat->cs_tfm_mutex);
324 rc = -EINVAL;
325 goto out;
326 }
327 ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size);
8bba066f 328 crypto_blkcipher_encrypt_iv(&desc, dest_sg, src_sg, size);
237fead6
MH		 329 mutex_unlock(&crypt_stat->cs_tfm_mutex);
330out:
331 return rc;
332}
333
334static void
335ecryptfs_extent_to_lwr_pg_idx_and_offset(unsigned long *lower_page_idx,
336 int *byte_offset,
337 struct ecryptfs_crypt_stat *crypt_stat,
338 unsigned long extent_num)
339{
340 unsigned long lower_extent_num;
341 int extents_occupied_by_headers_at_front;
342 int bytes_occupied_by_headers_at_front;
343 int extent_offset;
344 int extents_per_page;
345
346 bytes_occupied_by_headers_at_front =
347 ( crypt_stat->header_extent_size
348 * crypt_stat->num_header_extents_at_front );
349 extents_occupied_by_headers_at_front =
350 ( bytes_occupied_by_headers_at_front
351 / crypt_stat->extent_size );
352 lower_extent_num = extents_occupied_by_headers_at_front + extent_num;
353 extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size;
354 (*lower_page_idx) = lower_extent_num / extents_per_page;
355 extent_offset = lower_extent_num % extents_per_page;
356 (*byte_offset) = extent_offset * crypt_stat->extent_size;
357 ecryptfs_printk(KERN_DEBUG, " * crypt_stat->header_extent_size = "
358 "[%d]\n", crypt_stat->header_extent_size);
359 ecryptfs_printk(KERN_DEBUG, " * crypt_stat->"
360 "num_header_extents_at_front = [%d]\n",
361 crypt_stat->num_header_extents_at_front);
362 ecryptfs_printk(KERN_DEBUG, " * extents_occupied_by_headers_at_"
363 "front = [%d]\n", extents_occupied_by_headers_at_front);
364 ecryptfs_printk(KERN_DEBUG, " * lower_extent_num = [0x%.16x]\n",
365 lower_extent_num);
366 ecryptfs_printk(KERN_DEBUG, " * extents_per_page = [%d]\n",
367 extents_per_page);
368 ecryptfs_printk(KERN_DEBUG, " * (*lower_page_idx) = [0x%.16x]\n",
369 (*lower_page_idx));
370 ecryptfs_printk(KERN_DEBUG, " * extent_offset = [%d]\n",
371 extent_offset);
372 ecryptfs_printk(KERN_DEBUG, " * (*byte_offset) = [%d]\n",
373 (*byte_offset));
374}
375
376static int ecryptfs_write_out_page(struct ecryptfs_page_crypt_context *ctx,
377 struct page *lower_page,
378 struct inode *lower_inode,
379 int byte_offset_in_page, int bytes_to_write)
380{
381 int rc = 0;
382
383 if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) {
384 rc = ecryptfs_commit_lower_page(lower_page, lower_inode,
385 ctx->param.lower_file,
386 byte_offset_in_page,
387 bytes_to_write);
388 if (rc) {
389 ecryptfs_printk(KERN_ERR, "Error calling lower "
390 "commit; rc = [%d]\n", rc);
391 goto out;
392 }
393 } else {
394 rc = ecryptfs_writepage_and_release_lower_page(lower_page,
395 lower_inode,
396 ctx->param.wbc);
397 if (rc) {
398 ecryptfs_printk(KERN_ERR, "Error calling lower "
399 "writepage(); rc = [%d]\n", rc);
400 goto out;
401 }
402 }
403out:
404 return rc;
405}
406
407static int ecryptfs_read_in_page(struct ecryptfs_page_crypt_context *ctx,
408 struct page **lower_page,
409 struct inode *lower_inode,
410 unsigned long lower_page_idx,
411 int byte_offset_in_page)
412{
413 int rc = 0;
414
415 if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) {
416 /* TODO: Limit this to only the data extents that are
417 * needed */
418 rc = ecryptfs_get_lower_page(lower_page, lower_inode,
419 ctx->param.lower_file,
420 lower_page_idx,
421 byte_offset_in_page,
422 (PAGE_CACHE_SIZE
423 - byte_offset_in_page));
424 if (rc) {
425 ecryptfs_printk(
426 KERN_ERR, "Error attempting to grab, map, "
427 "and prepare_write lower page with index "
428 "[0x%.16x]; rc = [%d]\n", lower_page_idx, rc);
429 goto out;
430 }
431 } else {
432 rc = ecryptfs_grab_and_map_lower_page(lower_page, NULL,
433 lower_inode,
434 lower_page_idx);
435 if (rc) {
436 ecryptfs_printk(
437 KERN_ERR, "Error attempting to grab and map "
438 "lower page with index [0x%.16x]; rc = [%d]\n",
439 lower_page_idx, rc);
440 goto out;
441 }
442 }
443out:
444 return rc;
445}
446
447/**
448 * ecryptfs_encrypt_page
449 * @ctx: The context of the page
450 *
451 * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
452 * that eCryptfs pages may straddle the lower pages -- for instance,
453 * if the file was created on a machine with an 8K page size
454 * (resulting in an 8K header), and then the file is copied onto a
455 * host with a 32K page size, then when reading page 0 of the eCryptfs
456 * file, 24K of page 0 of the lower file will be read and decrypted,
457 * and then 8K of page 1 of the lower file will be read and decrypted.
458 *
459 * The actual operations performed on each page depends on the
460 * contents of the ecryptfs_page_crypt_context struct.
461 *
462 * Returns zero on success; negative on error
463 */
464int ecryptfs_encrypt_page(struct ecryptfs_page_crypt_context *ctx)
465{
466 char extent_iv[ECRYPTFS_MAX_IV_BYTES];
467 unsigned long base_extent;
468 unsigned long extent_offset = 0;
469 unsigned long lower_page_idx = 0;
470 unsigned long prior_lower_page_idx = 0;
471 struct page *lower_page;
472 struct inode *lower_inode;
473 struct ecryptfs_inode_info *inode_info;
474 struct ecryptfs_crypt_stat *crypt_stat;
475 int rc = 0;
476 int lower_byte_offset = 0;
477 int orig_byte_offset = 0;
478 int num_extents_per_page;
479#define ECRYPTFS_PAGE_STATE_UNREAD 0
480#define ECRYPTFS_PAGE_STATE_READ 1
481#define ECRYPTFS_PAGE_STATE_MODIFIED 2
482#define ECRYPTFS_PAGE_STATE_WRITTEN 3
483 int page_state;
484
485 lower_inode = ecryptfs_inode_to_lower(ctx->page->mapping->host);
486 inode_info = ecryptfs_inode_to_private(ctx->page->mapping->host);
487 crypt_stat = &inode_info->crypt_stat;
488 if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED)) {
489 rc = ecryptfs_copy_page_to_lower(ctx->page, lower_inode,
490 ctx->param.lower_file);
491 if (rc)
492 ecryptfs_printk(KERN_ERR, "Error attempting to copy "
493 "page at index [0x%.16x]\n",
494 ctx->page->index);
495 goto out;
496 }
497 num_extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size;
498 base_extent = (ctx->page->index * num_extents_per_page);
499 page_state = ECRYPTFS_PAGE_STATE_UNREAD;
500 while (extent_offset < num_extents_per_page) {
501 ecryptfs_extent_to_lwr_pg_idx_and_offset(
502 &lower_page_idx, &lower_byte_offset, crypt_stat,
503 (base_extent + extent_offset));
504 if (prior_lower_page_idx != lower_page_idx
505 && page_state == ECRYPTFS_PAGE_STATE_MODIFIED) {
506 rc = ecryptfs_write_out_page(ctx, lower_page,
507 lower_inode,
508 orig_byte_offset,
509 (PAGE_CACHE_SIZE
510 - orig_byte_offset));
511 if (rc) {
512 ecryptfs_printk(KERN_ERR, "Error attempting "
513 "to write out page; rc = [%d]"
514 "\n", rc);
515 goto out;
516 }
517 page_state = ECRYPTFS_PAGE_STATE_WRITTEN;
518 }
519 if (page_state == ECRYPTFS_PAGE_STATE_UNREAD
520 || page_state == ECRYPTFS_PAGE_STATE_WRITTEN) {
521 rc = ecryptfs_read_in_page(ctx, &lower_page,
522 lower_inode, lower_page_idx,
523 lower_byte_offset);
524 if (rc) {
525 ecryptfs_printk(KERN_ERR, "Error attempting "
526 "to read in lower page with "
527 "index [0x%.16x]; rc = [%d]\n",
528 lower_page_idx, rc);
529 goto out;
530 }
531 orig_byte_offset = lower_byte_offset;
532 prior_lower_page_idx = lower_page_idx;
533 page_state = ECRYPTFS_PAGE_STATE_READ;
534 }
535 BUG_ON(!(page_state == ECRYPTFS_PAGE_STATE_MODIFIED
536 || page_state == ECRYPTFS_PAGE_STATE_READ));
537 rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
538 (base_extent + extent_offset));
539 if (rc) {
540 ecryptfs_printk(KERN_ERR, "Error attempting to "
541 "derive IV for extent [0x%.16x]; "
542 "rc = [%d]\n",
543 (base_extent + extent_offset), rc);
544 goto out;
545 }
546 if (unlikely(ecryptfs_verbosity > 0)) {
547 ecryptfs_printk(KERN_DEBUG, "Encrypting extent "
548 "with iv:\n");
549 ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
550 ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
551 "encryption:\n");
552 ecryptfs_dump_hex((char *)
553 (page_address(ctx->page)
554 + (extent_offset
555 * crypt_stat->extent_size)), 8);
556 }
557 rc = ecryptfs_encrypt_page_offset(
558 crypt_stat, lower_page, lower_byte_offset, ctx->page,
559 (extent_offset * crypt_stat->extent_size),
560 crypt_stat->extent_size, extent_iv);
561 ecryptfs_printk(KERN_DEBUG, "Encrypt extent [0x%.16x]; "
562 "rc = [%d]\n",
563 (base_extent + extent_offset), rc);
564 if (unlikely(ecryptfs_verbosity > 0)) {
565 ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
566 "encryption:\n");
567 ecryptfs_dump_hex((char *)(page_address(lower_page)
568 + lower_byte_offset), 8);
569 }
570 page_state = ECRYPTFS_PAGE_STATE_MODIFIED;
571 extent_offset++;
572 }
573 BUG_ON(orig_byte_offset != 0);
574 rc = ecryptfs_write_out_page(ctx, lower_page, lower_inode, 0,
575 (lower_byte_offset
576 + crypt_stat->extent_size));
577 if (rc) {
578 ecryptfs_printk(KERN_ERR, "Error attempting to write out "
579 "page; rc = [%d]\n", rc);
580 goto out;
581 }
582out:
583 return rc;
584}
585
586/**
587 * ecryptfs_decrypt_page
588 * @file: The ecryptfs file
589 * @page: The page in ecryptfs to decrypt
590 *
591 * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
592 * that eCryptfs pages may straddle the lower pages -- for instance,
593 * if the file was created on a machine with an 8K page size
594 * (resulting in an 8K header), and then the file is copied onto a
595 * host with a 32K page size, then when reading page 0 of the eCryptfs
596 * file, 24K of page 0 of the lower file will be read and decrypted,
597 * and then 8K of page 1 of the lower file will be read and decrypted.
598 *
599 * Returns zero on success; negative on error
600 */
601int ecryptfs_decrypt_page(struct file *file, struct page *page)
602{
603 char extent_iv[ECRYPTFS_MAX_IV_BYTES];
604 unsigned long base_extent;
605 unsigned long extent_offset = 0;
606 unsigned long lower_page_idx = 0;
607 unsigned long prior_lower_page_idx = 0;
608 struct page *lower_page;
609 char *lower_page_virt = NULL;
610 struct inode *lower_inode;
611 struct ecryptfs_crypt_stat *crypt_stat;
612 int rc = 0;
613 int byte_offset;
614 int num_extents_per_page;
615 int page_state;
616
617 crypt_stat = &(ecryptfs_inode_to_private(
618 page->mapping->host)->crypt_stat);
619 lower_inode = ecryptfs_inode_to_lower(page->mapping->host);
620 if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED)) {
621 rc = ecryptfs_do_readpage(file, page, page->index);
622 if (rc)
623 ecryptfs_printk(KERN_ERR, "Error attempting to copy "
624 "page at index [0x%.16x]\n",
625 page->index);
626 goto out;
627 }
628 num_extents_per_page = PAGE_CACHE_SIZE / crypt_stat->extent_size;
629 base_extent = (page->index * num_extents_per_page);
630 lower_page_virt = kmem_cache_alloc(ecryptfs_lower_page_cache,
631 SLAB_KERNEL);
632 if (!lower_page_virt) {
633 rc = -ENOMEM;
634 ecryptfs_printk(KERN_ERR, "Error getting page for encrypted "
635 "lower page(s)\n");
636 goto out;
637 }
638 lower_page = virt_to_page(lower_page_virt);
639 page_state = ECRYPTFS_PAGE_STATE_UNREAD;
640 while (extent_offset < num_extents_per_page) {
641 ecryptfs_extent_to_lwr_pg_idx_and_offset(
642 &lower_page_idx, &byte_offset, crypt_stat,
643 (base_extent + extent_offset));
644 if (prior_lower_page_idx != lower_page_idx
645 || page_state == ECRYPTFS_PAGE_STATE_UNREAD) {
646 rc = ecryptfs_do_readpage(file, lower_page,
647 lower_page_idx);
648 if (rc) {
649 ecryptfs_printk(KERN_ERR, "Error reading "
650 "lower encrypted page; rc = "
651 "[%d]\n", rc);
652 goto out;
653 }
654 prior_lower_page_idx = lower_page_idx;
655 page_state = ECRYPTFS_PAGE_STATE_READ;
656 }
657 rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
658 (base_extent + extent_offset));
659 if (rc) {
660 ecryptfs_printk(KERN_ERR, "Error attempting to "
661 "derive IV for extent [0x%.16x]; rc = "
662 "[%d]\n",
663 (base_extent + extent_offset), rc);
664 goto out;
665 }
666 if (unlikely(ecryptfs_verbosity > 0)) {
667 ecryptfs_printk(KERN_DEBUG, "Decrypting extent "
668 "with iv:\n");
669 ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
670 ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
671 "decryption:\n");
672 ecryptfs_dump_hex((lower_page_virt + byte_offset), 8);
673 }
674 rc = ecryptfs_decrypt_page_offset(crypt_stat, page,
675 (extent_offset
676 * crypt_stat->extent_size),
677 lower_page, byte_offset,
678 crypt_stat->extent_size,
679 extent_iv);
680 if (rc != crypt_stat->extent_size) {
681 ecryptfs_printk(KERN_ERR, "Error attempting to "
682 "decrypt extent [0x%.16x]\n",
683 (base_extent + extent_offset));
684 goto out;
685 }
686 rc = 0;
687 if (unlikely(ecryptfs_verbosity > 0)) {
688 ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
689 "decryption:\n");
690 ecryptfs_dump_hex((char *)(page_address(page)
691 + byte_offset), 8);
692 }
693 extent_offset++;
694 }
695out:
696 if (lower_page_virt)
697 kmem_cache_free(ecryptfs_lower_page_cache, lower_page_virt);
698 return rc;
699}
700
701/**
702 * decrypt_scatterlist
703 *
704 * Returns the number of bytes decrypted; negative value on error
705 */
706static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
707 struct scatterlist *dest_sg,
708 struct scatterlist *src_sg, int size,
709 unsigned char *iv)
710{
8bba066f
MH		 711 struct blkcipher_desc desc = {
712 .tfm = crypt_stat->tfm,
713 .info = iv,
714 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
715 };
237fead6
MH		 716 int rc = 0;
717
718 /* Consider doing this once, when the file is opened */
719 mutex_lock(&crypt_stat->cs_tfm_mutex);
8bba066f
MH		 720 rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
721 crypt_stat->key_size);
237fead6
MH		 722 if (rc) {
723 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
724 rc);
725 mutex_unlock(&crypt_stat->cs_tfm_mutex);
726 rc = -EINVAL;
727 goto out;
728 }
729 ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size);
8bba066f 730 rc = crypto_blkcipher_decrypt_iv(&desc, dest_sg, src_sg, size);
237fead6
MH		 731 mutex_unlock(&crypt_stat->cs_tfm_mutex);
732 if (rc) {
733 ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n",
734 rc);
735 goto out;
736 }
737 rc = size;
738out:
739 return rc;
740}
741
742/**
743 * ecryptfs_encrypt_page_offset
744 *
745 * Returns the number of bytes encrypted
746 */
747static int
748ecryptfs_encrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
749 struct page *dst_page, int dst_offset,
750 struct page *src_page, int src_offset, int size,
751 unsigned char *iv)
752{
753 struct scatterlist src_sg, dst_sg;
754
755 src_sg.page = src_page;
756 src_sg.offset = src_offset;
757 src_sg.length = size;
758 dst_sg.page = dst_page;
759 dst_sg.offset = dst_offset;
760 dst_sg.length = size;
761 return encrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
762}
763
764/**
765 * ecryptfs_decrypt_page_offset
766 *
767 * Returns the number of bytes decrypted
768 */
769static int
770ecryptfs_decrypt_page_offset(struct ecryptfs_crypt_stat *crypt_stat,
771 struct page *dst_page, int dst_offset,
772 struct page *src_page, int src_offset, int size,
773 unsigned char *iv)
774{
775 struct scatterlist src_sg, dst_sg;
776
777 src_sg.page = src_page;
778 src_sg.offset = src_offset;
779 src_sg.length = size;
780 dst_sg.page = dst_page;
781 dst_sg.offset = dst_offset;
782 dst_sg.length = size;
783 return decrypt_scatterlist(crypt_stat, &dst_sg, &src_sg, size, iv);
784}
785
786#define ECRYPTFS_MAX_SCATTERLIST_LEN 4
787
788/**
789 * ecryptfs_init_crypt_ctx
790 * @crypt_stat: Uninitilized crypt stats structure
791 *
792 * Initialize the crypto context.
793 *
794 * TODO: Performance: Keep a cache of initialized cipher contexts;
795 * only init if needed
796 */
797int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
798{
8bba066f 799 char *full_alg_name;
237fead6
MH		 800 int rc = -EINVAL;
801
802 if (!crypt_stat->cipher) {
803 ecryptfs_printk(KERN_ERR, "No cipher specified\n");
804 goto out;
805 }
806 ecryptfs_printk(KERN_DEBUG,
807 "Initializing cipher [%s]; strlen = [%d]; "
808 "key_size_bits = [%d]\n",
809 crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
810 crypt_stat->key_size << 3);
811 if (crypt_stat->tfm) {
812 rc = 0;
813 goto out;
814 }
815 mutex_lock(&crypt_stat->cs_tfm_mutex);
8bba066f
MH		 816 rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
817 crypt_stat->cipher, "cbc");
818 if (rc)
819 goto out;
820 crypt_stat->tfm = crypto_alloc_blkcipher(full_alg_name, 0,
821 CRYPTO_ALG_ASYNC);
822 kfree(full_alg_name);
237fead6
MH		 823 if (!crypt_stat->tfm) {
824 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
825 "Error initializing cipher [%s]\n",
826 crypt_stat->cipher);
8bba066f 827 mutex_unlock(&crypt_stat->cs_tfm_mutex);
237fead6
MH		 828 goto out;
829 }
8bba066f
MH		 830 crypto_blkcipher_set_flags(crypt_stat->tfm,
831 (ECRYPTFS_DEFAULT_CHAINING_MODE
832 | CRYPTO_TFM_REQ_WEAK_KEY));
833 mutex_unlock(&crypt_stat->cs_tfm_mutex);
237fead6
MH		 834 rc = 0;
835out:
836 return rc;
837}
838
839static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
840{
841 int extent_size_tmp;
842
843 crypt_stat->extent_mask = 0xFFFFFFFF;
844 crypt_stat->extent_shift = 0;
845 if (crypt_stat->extent_size == 0)
846 return;
847 extent_size_tmp = crypt_stat->extent_size;
848 while ((extent_size_tmp & 0x01) == 0) {
849 extent_size_tmp >>= 1;
850 crypt_stat->extent_mask <<= 1;
851 crypt_stat->extent_shift++;
852 }
853}
854
855void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
856{
857 /* Default values; may be overwritten as we are parsing the
858 * packets. */
859 crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
860 set_extent_mask_and_shift(crypt_stat);
861 crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
862 if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) {
863 crypt_stat->header_extent_size =
864 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
865 } else
866 crypt_stat->header_extent_size = PAGE_CACHE_SIZE;
867 crypt_stat->num_header_extents_at_front = 1;
868}
869
870/**
871 * ecryptfs_compute_root_iv
872 * @crypt_stats
873 *
874 * On error, sets the root IV to all 0's.
875 */
876int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
877{
878 int rc = 0;
879 char dst[MD5_DIGEST_SIZE];
880
881 BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
882 BUG_ON(crypt_stat->iv_bytes <= 0);
883 if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID)) {
884 rc = -EINVAL;
885 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
886 "cannot generate root IV\n");
887 goto out;
888 }
889 rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
890 crypt_stat->key_size);
891 if (rc) {
892 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
893 "MD5 while generating root IV\n");
894 goto out;
895 }
896 memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
897out:
898 if (rc) {
899 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
900 ECRYPTFS_SET_FLAG(crypt_stat->flags,
901 ECRYPTFS_SECURITY_WARNING);
902 }
903 return rc;
904}
905
906static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
907{
908 get_random_bytes(crypt_stat->key, crypt_stat->key_size);
909 ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
910 ecryptfs_compute_root_iv(crypt_stat);
911 if (unlikely(ecryptfs_verbosity > 0)) {
912 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
913 ecryptfs_dump_hex(crypt_stat->key,
914 crypt_stat->key_size);
915 }
916}
917
918/**
919 * ecryptfs_set_default_crypt_stat_vals
920 * @crypt_stat
921 *
922 * Default values in the event that policy does not override them.
923 */
924static void ecryptfs_set_default_crypt_stat_vals(
925 struct ecryptfs_crypt_stat *crypt_stat,
926 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
927{
928 ecryptfs_set_default_sizes(crypt_stat);
929 strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
930 crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
931 ECRYPTFS_CLEAR_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
932 crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
933 crypt_stat->mount_crypt_stat = mount_crypt_stat;
934}
935
936/**
937 * ecryptfs_new_file_context
938 * @ecryptfs_dentry
939 *
940 * If the crypto context for the file has not yet been established,
941 * this is where we do that. Establishing a new crypto context
942 * involves the following decisions:
943 * - What cipher to use?
944 * - What set of authentication tokens to use?
945 * Here we just worry about getting enough information into the
946 * authentication tokens so that we know that they are available.
947 * We associate the available authentication tokens with the new file
948 * via the set of signatures in the crypt_stat struct. Later, when
949 * the headers are actually written out, we may again defer to
950 * userspace to perform the encryption of the session key; for the
951 * foreseeable future, this will be the case with public key packets.
952 *
953 * Returns zero on success; non-zero otherwise
954 */
955/* Associate an authentication token(s) with the file */
956int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry)
957{
958 int rc = 0;
959 struct ecryptfs_crypt_stat *crypt_stat =
960 &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
961 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
962 &ecryptfs_superblock_to_private(
963 ecryptfs_dentry->d_sb)->mount_crypt_stat;
964 int cipher_name_len;
965
966 ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
967 /* See if there are mount crypt options */
968 if (mount_crypt_stat->global_auth_tok) {
969 ecryptfs_printk(KERN_DEBUG, "Initializing context for new "
970 "file using mount_crypt_stat\n");
971 ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED);
972 ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
973 memcpy(crypt_stat->keysigs[crypt_stat->num_keysigs++],
974 mount_crypt_stat->global_auth_tok_sig,
975 ECRYPTFS_SIG_SIZE_HEX);
976 cipher_name_len =
977 strlen(mount_crypt_stat->global_default_cipher_name);
978 memcpy(crypt_stat->cipher,
979 mount_crypt_stat->global_default_cipher_name,
980 cipher_name_len);
981 crypt_stat->cipher[cipher_name_len] = '\0';
982 crypt_stat->key_size =
983 mount_crypt_stat->global_default_cipher_key_size;
984 ecryptfs_generate_new_key(crypt_stat);
985 } else
986 /* We should not encounter this scenario since we
987 * should detect lack of global_auth_tok at mount time
988 * TODO: Applies to 0.1 release only; remove in future
989 * release */
990 BUG();
991 rc = ecryptfs_init_crypt_ctx(crypt_stat);
992 if (rc)
993 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
994 "context for cipher [%s]: rc = [%d]\n",
995 crypt_stat->cipher, rc);
996 return rc;
997}
998
999/**
1000 * contains_ecryptfs_marker - check for the ecryptfs marker
1001 * @data: The data block in which to check
1002 *
1003 * Returns one if marker found; zero if not found
1004 */
1005int contains_ecryptfs_marker(char *data)
1006{
1007 u32 m_1, m_2;
1008
1009 memcpy(&m_1, data, 4);
1010 m_1 = be32_to_cpu(m_1);
1011 memcpy(&m_2, (data + 4), 4);
1012 m_2 = be32_to_cpu(m_2);
1013 if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
1014 return 1;
1015 ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
1016 "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
1017 MAGIC_ECRYPTFS_MARKER);
1018 ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
1019 "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
1020 return 0;
1021}
1022
1023struct ecryptfs_flag_map_elem {
1024 u32 file_flag;
1025 u32 local_flag;
1026};
1027
1028/* Add support for additional flags by adding elements here. */
1029static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
1030 {0x00000001, ECRYPTFS_ENABLE_HMAC},
1031 {0x00000002, ECRYPTFS_ENCRYPTED}
1032};
1033
1034/**
1035 * ecryptfs_process_flags
1036 * @crypt_stat
1037 * @page_virt: Source data to be parsed
1038 * @bytes_read: Updated with the number of bytes read
1039 *
1040 * Returns zero on success; non-zero if the flag set is invalid
1041 */
1042static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
1043 char *page_virt, int *bytes_read)
1044{
1045 int rc = 0;
1046 int i;
1047 u32 flags;
1048
1049 memcpy(&flags, page_virt, 4);
1050 flags = be32_to_cpu(flags);
1051 for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1052 / sizeof(struct ecryptfs_flag_map_elem))); i++)
1053 if (flags & ecryptfs_flag_map[i].file_flag) {
1054 ECRYPTFS_SET_FLAG(crypt_stat->flags,
1055 ecryptfs_flag_map[i].local_flag);
1056 } else
1057 ECRYPTFS_CLEAR_FLAG(crypt_stat->flags,
1058 ecryptfs_flag_map[i].local_flag);
1059 /* Version is in top 8 bits of the 32-bit flag vector */
1060 crypt_stat->file_version = ((flags >> 24) & 0xFF);
1061 (*bytes_read) = 4;
1062 return rc;
1063}
1064
1065/**
1066 * write_ecryptfs_marker
1067 * @page_virt: The pointer to in a page to begin writing the marker
1068 * @written: Number of bytes written
1069 *
1070 * Marker = 0x3c81b7f5
1071 */
1072static void write_ecryptfs_marker(char *page_virt, size_t *written)
1073{
1074 u32 m_1, m_2;
1075
1076 get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1077 m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
1078 m_1 = cpu_to_be32(m_1);
1079 memcpy(page_virt, &m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1080 m_2 = cpu_to_be32(m_2);
1081 memcpy(page_virt + (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2), &m_2,
1082 (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1083 (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1084}
1085
1086static void
1087write_ecryptfs_flags(char *page_virt, struct ecryptfs_crypt_stat *crypt_stat,
1088 size_t *written)
1089{
1090 u32 flags = 0;
1091 int i;
1092
1093 for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1094 / sizeof(struct ecryptfs_flag_map_elem))); i++)
1095 if (ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
1096 ecryptfs_flag_map[i].local_flag))
1097 flags |= ecryptfs_flag_map[i].file_flag;
1098 /* Version is in top 8 bits of the 32-bit flag vector */
1099 flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
1100 flags = cpu_to_be32(flags);
1101 memcpy(page_virt, &flags, 4);
1102 (*written) = 4;
1103}
1104
1105struct ecryptfs_cipher_code_str_map_elem {
1106 char cipher_str[16];
1107 u16 cipher_code;
1108};
1109
1110/* Add support for additional ciphers by adding elements here. The
1111 * cipher_code is whatever OpenPGP applicatoins use to identify the
1112 * ciphers. List in order of probability. */
1113static struct ecryptfs_cipher_code_str_map_elem
1114ecryptfs_cipher_code_str_map[] = {
1115 {"aes",RFC2440_CIPHER_AES_128 },
1116 {"blowfish", RFC2440_CIPHER_BLOWFISH},
1117 {"des3_ede", RFC2440_CIPHER_DES3_EDE},
1118 {"cast5", RFC2440_CIPHER_CAST_5},
1119 {"twofish", RFC2440_CIPHER_TWOFISH},
1120 {"cast6", RFC2440_CIPHER_CAST_6},
1121 {"aes", RFC2440_CIPHER_AES_192},
1122 {"aes", RFC2440_CIPHER_AES_256}
1123};
1124
1125/**
1126 * ecryptfs_code_for_cipher_string
1127 * @str: The string representing the cipher name
1128 *
1129 * Returns zero on no match, or the cipher code on match
1130 */
1131u16 ecryptfs_code_for_cipher_string(struct ecryptfs_crypt_stat *crypt_stat)
1132{
1133 int i;
1134 u16 code = 0;
1135 struct ecryptfs_cipher_code_str_map_elem *map =
1136 ecryptfs_cipher_code_str_map;
1137
1138 if (strcmp(crypt_stat->cipher, "aes") == 0) {
1139 switch (crypt_stat->key_size) {
1140 case 16:
1141 code = RFC2440_CIPHER_AES_128;
1142 break;
1143 case 24:
1144 code = RFC2440_CIPHER_AES_192;
1145 break;
1146 case 32:
1147 code = RFC2440_CIPHER_AES_256;
1148 }
1149 } else {
1150 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1151 if (strcmp(crypt_stat->cipher, map[i].cipher_str) == 0){
1152 code = map[i].cipher_code;
1153 break;
1154 }
1155 }
1156 return code;
1157}
1158
1159/**
1160 * ecryptfs_cipher_code_to_string
1161 * @str: Destination to write out the cipher name
1162 * @cipher_code: The code to convert to cipher name string
1163 *
1164 * Returns zero on success
1165 */
1166int ecryptfs_cipher_code_to_string(char *str, u16 cipher_code)
1167{
1168 int rc = 0;
1169 int i;
1170
1171 str[0] = '\0';
1172 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1173 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
1174 strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
1175 if (str[0] == '\0') {
1176 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
1177 "[%d]\n", cipher_code);
1178 rc = -EINVAL;
1179 }
1180 return rc;
1181}
1182
1183/**
1184 * ecryptfs_read_header_region
1185 * @data
1186 * @dentry
1187 * @nd
1188 *
1189 * Returns zero on success; non-zero otherwise
1190 */
1191int ecryptfs_read_header_region(char *data, struct dentry *dentry,
1192 struct vfsmount *mnt)
1193{
7ff1d74f 1194 struct file *lower_file;
237fead6
MH		 1195 mm_segment_t oldfs;
1196 int rc;
1197
7ff1d74f
MH		 1198 if ((rc = ecryptfs_open_lower_file(&lower_file, dentry, mnt,
1199 O_RDONLY))) {
1200 printk(KERN_ERR
1201 "Error opening lower_file to read header region\n");
237fead6
MH		 1202 goto out;
1203 }
7ff1d74f 1204 lower_file->f_pos = 0;
237fead6
MH		 1205 oldfs = get_fs();
1206 set_fs(get_ds());
1207 /* For releases 0.1 and 0.2, all of the header information
1208 * fits in the first data extent-sized region. */
7ff1d74f
MH		 1209 rc = lower_file->f_op->read(lower_file, (char __user *)data,
1210 ECRYPTFS_DEFAULT_EXTENT_SIZE, &lower_file->f_pos);
237fead6 1211 set_fs(oldfs);
7ff1d74f
MH		 1212 if ((rc = ecryptfs_close_lower_file(lower_file))) {
1213 printk(KERN_ERR "Error closing lower_file\n");
1214 goto out;
1215 }
237fead6
MH		 1216 rc = 0;
1217out:
1218 return rc;
1219}
1220
1221static void
1222write_header_metadata(char *virt, struct ecryptfs_crypt_stat *crypt_stat,
1223 size_t *written)
1224{
1225 u32 header_extent_size;
1226 u16 num_header_extents_at_front;
1227
1228 header_extent_size = (u32)crypt_stat->header_extent_size;
1229 num_header_extents_at_front =
1230 (u16)crypt_stat->num_header_extents_at_front;
1231 header_extent_size = cpu_to_be32(header_extent_size);
1232 memcpy(virt, &header_extent_size, 4);
1233 virt += 4;
1234 num_header_extents_at_front = cpu_to_be16(num_header_extents_at_front);
1235 memcpy(virt, &num_header_extents_at_front, 2);
1236 (*written) = 6;
1237}
1238
1239struct kmem_cache *ecryptfs_header_cache_0;
1240struct kmem_cache *ecryptfs_header_cache_1;
1241struct kmem_cache *ecryptfs_header_cache_2;
1242
1243/**
1244 * ecryptfs_write_headers_virt
1245 * @page_virt
1246 * @crypt_stat
1247 * @ecryptfs_dentry
1248 *
1249 * Format version: 1
1250 *
1251 * Header Extent:
1252 * Octets 0-7: Unencrypted file size (big-endian)
1253 * Octets 8-15: eCryptfs special marker
1254 * Octets 16-19: Flags
1255 * Octet 16: File format version number (between 0 and 255)
1256 * Octets 17-18: Reserved
1257 * Octet 19: Bit 1 (lsb): Reserved
1258 * Bit 2: Encrypted?
1259 * Bits 3-8: Reserved
1260 * Octets 20-23: Header extent size (big-endian)
1261 * Octets 24-25: Number of header extents at front of file
1262 * (big-endian)
1263 * Octet 26: Begin RFC 2440 authentication token packet set
1264 * Data Extent 0:
1265 * Lower data (CBC encrypted)
1266 * Data Extent 1:
1267 * Lower data (CBC encrypted)
1268 * ...
1269 *
1270 * Returns zero on success
1271 */
1272int ecryptfs_write_headers_virt(char *page_virt,
1273 struct ecryptfs_crypt_stat *crypt_stat,
1274 struct dentry *ecryptfs_dentry)
1275{
1276 int rc;
1277 size_t written;
1278 size_t offset;
1279
1280 offset = ECRYPTFS_FILE_SIZE_BYTES;
1281 write_ecryptfs_marker((page_virt + offset), &written);
1282 offset += written;
1283 write_ecryptfs_flags((page_virt + offset), crypt_stat, &written);
1284 offset += written;
1285 write_header_metadata((page_virt + offset), crypt_stat, &written);
1286 offset += written;
1287 rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1288 ecryptfs_dentry, &written,
1289 PAGE_CACHE_SIZE - offset);
1290 if (rc)
1291 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1292 "set; rc = [%d]\n", rc);
1293 return rc;
1294}
1295
1296/**
1297 * ecryptfs_write_headers
1298 * @lower_file: The lower file struct, which was returned from dentry_open
1299 *
1300 * Write the file headers out. This will likely involve a userspace
1301 * callout, in which the session key is encrypted with one or more
1302 * public keys and/or the passphrase necessary to do the encryption is
1303 * retrieved via a prompt. Exactly what happens at this point should
1304 * be policy-dependent.
1305 *
1306 * Returns zero on success; non-zero on error
1307 */
1308int ecryptfs_write_headers(struct dentry *ecryptfs_dentry,
1309 struct file *lower_file)
1310{
1311 mm_segment_t oldfs;
1312 struct ecryptfs_crypt_stat *crypt_stat;
1313 char *page_virt;
1314 int current_header_page;
1315 int header_pages;
1316 int rc = 0;
1317
1318 crypt_stat = &ecryptfs_inode_to_private(
1319 ecryptfs_dentry->d_inode)->crypt_stat;
1320 if (likely(ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
1321 ECRYPTFS_ENCRYPTED))) {
1322 if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
1323 ECRYPTFS_KEY_VALID)) {
1324 ecryptfs_printk(KERN_DEBUG, "Key is "
1325 "invalid; bailing out\n");
1326 rc = -EINVAL;
1327 goto out;
1328 }
1329 } else {
1330 rc = -EINVAL;
1331 ecryptfs_printk(KERN_WARNING,
1332 "Called with crypt_stat->encrypted == 0\n");
1333 goto out;
1334 }
1335 /* Released in this function */
1336 page_virt = kmem_cache_alloc(ecryptfs_header_cache_0, SLAB_USER);
1337 if (!page_virt) {
1338 ecryptfs_printk(KERN_ERR, "Out of memory\n");
1339 rc = -ENOMEM;
1340 goto out;
1341 }
1342 memset(page_virt, 0, PAGE_CACHE_SIZE);
1343 rc = ecryptfs_write_headers_virt(page_virt, crypt_stat,
1344 ecryptfs_dentry);
1345 if (unlikely(rc)) {
1346 ecryptfs_printk(KERN_ERR, "Error whilst writing headers\n");
1347 memset(page_virt, 0, PAGE_CACHE_SIZE);
1348 goto out_free;
1349 }
1350 ecryptfs_printk(KERN_DEBUG,
1351 "Writing key packet set to underlying file\n");
1352 lower_file->f_pos = 0;
1353 oldfs = get_fs();
1354 set_fs(get_ds());
1355 ecryptfs_printk(KERN_DEBUG, "Calling lower_file->f_op->"
1356 "write() w/ header page; lower_file->f_pos = "
1357 "[0x%.16x]\n", lower_file->f_pos);
1358 lower_file->f_op->write(lower_file, (char __user *)page_virt,
1359 PAGE_CACHE_SIZE, &lower_file->f_pos);
1360 header_pages = ((crypt_stat->header_extent_size
1361 * crypt_stat->num_header_extents_at_front)
1362 / PAGE_CACHE_SIZE);
1363 memset(page_virt, 0, PAGE_CACHE_SIZE);
1364 current_header_page = 1;
1365 while (current_header_page < header_pages) {
1366 ecryptfs_printk(KERN_DEBUG, "Calling lower_file->f_op->"
1367 "write() w/ zero'd page; lower_file->f_pos = "
1368 "[0x%.16x]\n", lower_file->f_pos);
1369 lower_file->f_op->write(lower_file, (char __user *)page_virt,
1370 PAGE_CACHE_SIZE, &lower_file->f_pos);
1371 current_header_page++;
1372 }
1373 set_fs(oldfs);
1374 ecryptfs_printk(KERN_DEBUG,
1375 "Done writing key packet set to underlying file.\n");
1376out_free:
1377 kmem_cache_free(ecryptfs_header_cache_0, page_virt);
1378out:
1379 return rc;
1380}
1381
1382static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1383 char *virt, int *bytes_read)
1384{
1385 int rc = 0;
1386 u32 header_extent_size;
1387 u16 num_header_extents_at_front;
1388
1389 memcpy(&header_extent_size, virt, 4);
1390 header_extent_size = be32_to_cpu(header_extent_size);
1391 virt += 4;
1392 memcpy(&num_header_extents_at_front, virt, 2);
1393 num_header_extents_at_front = be16_to_cpu(num_header_extents_at_front);
1394 crypt_stat->header_extent_size = (int)header_extent_size;
1395 crypt_stat->num_header_extents_at_front =
1396 (int)num_header_extents_at_front;
1397 (*bytes_read) = 6;
1398 if ((crypt_stat->header_extent_size
1399 * crypt_stat->num_header_extents_at_front)
1400 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) {
1401 rc = -EINVAL;
1402 ecryptfs_printk(KERN_WARNING, "Invalid header extent size: "
1403 "[%d]\n", crypt_stat->header_extent_size);
1404 }
1405 return rc;
1406}
1407
1408/**
1409 * set_default_header_data
1410 *
1411 * For version 0 file format; this function is only for backwards
1412 * compatibility for files created with the prior versions of
1413 * eCryptfs.
1414 */
1415static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1416{
1417 crypt_stat->header_extent_size = 4096;
1418 crypt_stat->num_header_extents_at_front = 1;
1419}
1420
1421/**
1422 * ecryptfs_read_headers_virt
1423 *
1424 * Read/parse the header data. The header format is detailed in the
1425 * comment block for the ecryptfs_write_headers_virt() function.
1426 *
1427 * Returns zero on success
1428 */
1429static int ecryptfs_read_headers_virt(char *page_virt,
1430 struct ecryptfs_crypt_stat *crypt_stat,
1431 struct dentry *ecryptfs_dentry)
1432{
1433 int rc = 0;
1434 int offset;
1435 int bytes_read;
1436
1437 ecryptfs_set_default_sizes(crypt_stat);
1438 crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1439 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1440 offset = ECRYPTFS_FILE_SIZE_BYTES;
1441 rc = contains_ecryptfs_marker(page_virt + offset);
1442 if (rc == 0) {
1443 rc = -EINVAL;
1444 goto out;
1445 }
1446 offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1447 rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1448 &bytes_read);
1449 if (rc) {
1450 ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1451 goto out;
1452 }
1453 if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1454 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1455 "file version [%d] is supported by this "
1456 "version of eCryptfs\n",
1457 crypt_stat->file_version,
1458 ECRYPTFS_SUPPORTED_FILE_VERSION);
1459 rc = -EINVAL;
1460 goto out;
1461 }
1462 offset += bytes_read;
1463 if (crypt_stat->file_version >= 1) {
1464 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1465 &bytes_read);
1466 if (rc) {
1467 ecryptfs_printk(KERN_WARNING, "Error reading header "
1468 "metadata; rc = [%d]\n", rc);
1469 }
1470 offset += bytes_read;
1471 } else
1472 set_default_header_data(crypt_stat);
1473 rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1474 ecryptfs_dentry);
1475out:
1476 return rc;
1477}
1478
1479/**
1480 * ecryptfs_read_headers
1481 *
1482 * Returns zero if valid headers found and parsed; non-zero otherwise
1483 */
1484int ecryptfs_read_headers(struct dentry *ecryptfs_dentry,
1485 struct file *lower_file)
1486{
1487 int rc = 0;
1488 char *page_virt = NULL;
1489 mm_segment_t oldfs;
1490 ssize_t bytes_read;
1491 struct ecryptfs_crypt_stat *crypt_stat =
1492 &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
1493
1494 /* Read the first page from the underlying file */
1495 page_virt = kmem_cache_alloc(ecryptfs_header_cache_1, SLAB_USER);
1496 if (!page_virt) {
1497 rc = -ENOMEM;
1498 ecryptfs_printk(KERN_ERR, "Unable to allocate page_virt\n");
1499 goto out;
1500 }
1501 lower_file->f_pos = 0;
1502 oldfs = get_fs();
1503 set_fs(get_ds());
1504 bytes_read = lower_file->f_op->read(lower_file,
1505 (char __user *)page_virt,
1506 ECRYPTFS_DEFAULT_EXTENT_SIZE,
1507 &lower_file->f_pos);
1508 set_fs(oldfs);
1509 if (bytes_read != ECRYPTFS_DEFAULT_EXTENT_SIZE) {
1510 rc = -EINVAL;
1511 goto out;
1512 }
1513 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1514 ecryptfs_dentry);
1515 if (rc) {
1516 ecryptfs_printk(KERN_DEBUG, "Valid eCryptfs headers not "
1517 "found\n");
1518 rc = -EINVAL;
1519 }
1520out:
1521 if (page_virt) {
1522 memset(page_virt, 0, PAGE_CACHE_SIZE);
1523 kmem_cache_free(ecryptfs_header_cache_1, page_virt);
1524 }
1525 return rc;
1526}
1527
1528/**
1529 * ecryptfs_encode_filename - converts a plaintext file name to cipher text
1530 * @crypt_stat: The crypt_stat struct associated with the file anem to encode
1531 * @name: The plaintext name
1532 * @length: The length of the plaintext
1533 * @encoded_name: The encypted name
1534 *
1535 * Encrypts and encodes a filename into something that constitutes a
1536 * valid filename for a filesystem, with printable characters.
1537 *
1538 * We assume that we have a properly initialized crypto context,
1539 * pointed to by crypt_stat->tfm.
1540 *
1541 * TODO: Implement filename decoding and decryption here, in place of
1542 * memcpy. We are keeping the framework around for now to (1)
1543 * facilitate testing of the components needed to implement filename
1544 * encryption and (2) to provide a code base from which other
1545 * developers in the community can easily implement this feature.
1546 *
1547 * Returns the length of encoded filename; negative if error
1548 */
1549int
1550ecryptfs_encode_filename(struct ecryptfs_crypt_stat *crypt_stat,
1551 const char *name, int length, char **encoded_name)
1552{
1553 int error = 0;
1554
1555 (*encoded_name) = kmalloc(length + 2, GFP_KERNEL);
1556 if (!(*encoded_name)) {
1557 error = -ENOMEM;
1558 goto out;
1559 }
1560 /* TODO: Filename encryption is a scheduled feature for a
1561 * future version of eCryptfs. This function is here only for
1562 * the purpose of providing a framework for other developers
1563 * to easily implement filename encryption. Hint: Replace this
1564 * memcpy() with a call to encrypt and encode the
1565 * filename, the set the length accordingly. */
1566 memcpy((void *)(*encoded_name), (void *)name, length);
1567 (*encoded_name)[length] = '\0';
1568 error = length + 1;
1569out:
1570 return error;
1571}
1572
1573/**
1574 * ecryptfs_decode_filename - converts the cipher text name to plaintext
1575 * @crypt_stat: The crypt_stat struct associated with the file
1576 * @name: The filename in cipher text
1577 * @length: The length of the cipher text name
1578 * @decrypted_name: The plaintext name
1579 *
1580 * Decodes and decrypts the filename.
1581 *
1582 * We assume that we have a properly initialized crypto context,
1583 * pointed to by crypt_stat->tfm.
1584 *
1585 * TODO: Implement filename decoding and decryption here, in place of
1586 * memcpy. We are keeping the framework around for now to (1)
1587 * facilitate testing of the components needed to implement filename
1588 * encryption and (2) to provide a code base from which other
1589 * developers in the community can easily implement this feature.
1590 *
1591 * Returns the length of decoded filename; negative if error
1592 */
1593int
1594ecryptfs_decode_filename(struct ecryptfs_crypt_stat *crypt_stat,
1595 const char *name, int length, char **decrypted_name)
1596{
1597 int error = 0;
1598
1599 (*decrypted_name) = kmalloc(length + 2, GFP_KERNEL);
1600 if (!(*decrypted_name)) {
1601 error = -ENOMEM;
1602 goto out;
1603 }
1604 /* TODO: Filename encryption is a scheduled feature for a
1605 * future version of eCryptfs. This function is here only for
1606 * the purpose of providing a framework for other developers
1607 * to easily implement filename encryption. Hint: Replace this
1608 * memcpy() with a call to decode and decrypt the
1609 * filename, the set the length accordingly. */
1610 memcpy((void *)(*decrypted_name), (void *)name, length);
1611 (*decrypted_name)[length + 1] = '\0'; /* Only for convenience
1612 * in printing out the
1613 * string in debug
1614 * messages */
1615 error = length;
1616out:
1617 return error;
1618}
1619
1620/**
1621 * ecryptfs_process_cipher - Perform cipher initialization.
237fead6 1622 * @key_tfm: Crypto context for key material, set by this function
e5d9cbde
MH		 1623 * @cipher_name: Name of the cipher
1624 * @key_size: Size of the key in bytes
237fead6
MH		 1625 *
1626 * Returns zero on success. Any crypto_tfm structs allocated here
1627 * should be released by other functions, such as on a superblock put
1628 * event, regardless of whether this function succeeds for fails.
1629 */
1630int
8bba066f 1631ecryptfs_process_cipher(struct crypto_blkcipher **key_tfm, char *cipher_name,
e5d9cbde 1632 size_t *key_size)
237fead6
MH		 1633{
1634 char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
8bba066f 1635 char *full_alg_name;
237fead6
MH		 1636 int rc;
1637
e5d9cbde
MH		 1638 *key_tfm = NULL;
1639 if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
237fead6
MH		 1640 rc = -EINVAL;
1641 printk(KERN_ERR "Requested key size is [%Zd] bytes; maximum "
e5d9cbde 1642 "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
237fead6
MH		 1643 goto out;
1644 }
8bba066f
MH		 1645 rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1646 "ecb");
1647 if (rc)
1648 goto out;
1649 *key_tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1650 kfree(full_alg_name);
1651 if (IS_ERR(*key_tfm)) {
1652 rc = PTR_ERR(*key_tfm);
237fead6 1653 printk(KERN_ERR "Unable to allocate crypto cipher with name "
8bba066f 1654 "[%s]; rc = [%d]\n", cipher_name, rc);
237fead6
MH		 1655 goto out;
1656 }
8bba066f
MH		 1657 crypto_blkcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1658 if (*key_size == 0) {
1659 struct blkcipher_alg *alg = crypto_blkcipher_alg(*key_tfm);
1660
1661 *key_size = alg->max_keysize;
1662 }
e5d9cbde 1663 get_random_bytes(dummy_key, *key_size);
8bba066f 1664 rc = crypto_blkcipher_setkey(*key_tfm, dummy_key, *key_size);
237fead6
MH		 1665 if (rc) {
1666 printk(KERN_ERR "Error attempting to set key of size [%Zd] for "
e5d9cbde 1667 "cipher [%s]; rc = [%d]\n", *key_size, cipher_name, rc);
237fead6
MH		 1668 rc = -EINVAL;
1669 goto out;
1670 }
1671out:
1672 return rc;
1673}
Linux 6.x block layer and io_uring tree(s)