2 * eCryptfs: Linux filesystem encryption layer
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>
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.
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.
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
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"
39 ecryptfs_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,
44 ecryptfs_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,
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
56 void ecryptfs_to_hex(char *dst, char *src, size_t src_size)
60 for (x = 0; x < src_size; x++)
61 sprintf(&dst[x * 2], "%.2x", (unsigned char)src[x]);
66 * @dst: Buffer to take the bytes from src hex; must be at least of
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
71 void ecryptfs_from_hex(char *dst, char *src, int dst_size)
76 for (x = 0; x < dst_size; x++) {
78 tmp[1] = src[x * 2 + 1];
79 dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
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
90 * Uses the allocated crypto context that crypt_stat references to
91 * generate the MD5 sum of the contents of src.
93 static int ecryptfs_calculate_md5(char *dst,
94 struct ecryptfs_crypt_stat *crypt_stat,
97 struct scatterlist sg;
98 struct hash_desc desc = {
99 .tfm = crypt_stat->hash_tfm,
100 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
104 mutex_lock(&crypt_stat->cs_hash_tfm_mutex);
105 sg_init_one(&sg, (u8 *)src, len);
107 desc.tfm = crypto_alloc_hash(ECRYPTFS_DEFAULT_HASH, 0,
109 if (IS_ERR(desc.tfm)) {
110 rc = PTR_ERR(desc.tfm);
111 ecryptfs_printk(KERN_ERR, "Error attempting to "
112 "allocate crypto context; rc = [%d]\n",
116 crypt_stat->hash_tfm = desc.tfm;
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);
126 int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
128 char *chaining_modifier)
130 int cipher_name_len = strlen(cipher_name);
131 int chaining_modifier_len = strlen(chaining_modifier);
132 int algified_name_len;
135 algified_name_len = (chaining_modifier_len + cipher_name_len + 3);
136 (*algified_name) = kmalloc(algified_name_len, GFP_KERNEL);
137 if (!(*algified_name)) {
141 snprintf((*algified_name), algified_name_len, "%s(%s)",
142 chaining_modifier, cipher_name);
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
154 * Generate the initialization vector from the given root IV and page
157 * Returns zero on success; non-zero on error.
159 static int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
163 char dst[MD5_DIGEST_SIZE];
164 char src[ECRYPTFS_MAX_IV_BYTES + 16];
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);
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));
181 rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
182 (crypt_stat->iv_bytes + 16));
184 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
185 "MD5 while generating IV for a page\n");
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);
198 * ecryptfs_init_crypt_stat
199 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
201 * Initialize the crypt_stat structure.
204 ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
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);
209 mutex_init(&crypt_stat->cs_hash_tfm_mutex);
210 ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_STRUCT_INITIALIZED);
214 * ecryptfs_destruct_crypt_stat
215 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
217 * Releases all memory associated with a crypt_stat struct.
219 void ecryptfs_destruct_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
222 crypto_free_blkcipher(crypt_stat->tfm);
223 if (crypt_stat->hash_tfm)
224 crypto_free_hash(crypt_stat->hash_tfm);
225 memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
228 void ecryptfs_destruct_mount_crypt_stat(
229 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
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)
234 crypto_free_blkcipher(mount_crypt_stat->global_key_tfm);
235 memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
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
246 * Fills in a scatterlist array with page references for a passed
249 * Returns the number of scatterlist structs in array used
251 int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
257 int remainder_of_page;
259 while (size > 0 && i < sg_size) {
260 pg = virt_to_page(addr);
261 offset = offset_in_page(addr);
264 sg[i].offset = offset;
266 remainder_of_page = PAGE_CACHE_SIZE - offset;
267 if (size >= remainder_of_page) {
269 sg[i].length = remainder_of_page;
270 addr += remainder_of_page;
271 size -= remainder_of_page;
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
293 * Returns the number of bytes encrypted; negative value on error
295 static int encrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
296 struct scatterlist *dest_sg,
297 struct scatterlist *src_sg, int size,
300 struct blkcipher_desc desc = {
301 .tfm = crypt_stat->tfm,
303 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
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);
316 /* Consider doing this once, when the file is opened */
317 mutex_lock(&crypt_stat->cs_tfm_mutex);
318 rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
319 crypt_stat->key_size);
321 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
323 mutex_unlock(&crypt_stat->cs_tfm_mutex);
327 ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes.\n", size);
328 crypto_blkcipher_encrypt_iv(&desc, dest_sg, src_sg, size);
329 mutex_unlock(&crypt_stat->cs_tfm_mutex);
335 ecryptfs_extent_to_lwr_pg_idx_and_offset(unsigned long *lower_page_idx,
337 struct ecryptfs_crypt_stat *crypt_stat,
338 unsigned long extent_num)
340 unsigned long lower_extent_num;
341 int extents_occupied_by_headers_at_front;
342 int bytes_occupied_by_headers_at_front;
344 int extents_per_page;
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",
366 ecryptfs_printk(KERN_DEBUG, " * extents_per_page = [%d]\n",
368 ecryptfs_printk(KERN_DEBUG, " * (*lower_page_idx) = [0x%.16x]\n",
370 ecryptfs_printk(KERN_DEBUG, " * extent_offset = [%d]\n",
372 ecryptfs_printk(KERN_DEBUG, " * (*byte_offset) = [%d]\n",
376 static 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)
383 if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) {
384 rc = ecryptfs_commit_lower_page(lower_page, lower_inode,
385 ctx->param.lower_file,
389 ecryptfs_printk(KERN_ERR, "Error calling lower "
390 "commit; rc = [%d]\n", rc);
394 rc = ecryptfs_writepage_and_release_lower_page(lower_page,
398 ecryptfs_printk(KERN_ERR, "Error calling lower "
399 "writepage(); rc = [%d]\n", rc);
407 static 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)
415 if (ctx->mode == ECRYPTFS_PREPARE_COMMIT_MODE) {
416 /* TODO: Limit this to only the data extents that are
418 rc = ecryptfs_get_lower_page(lower_page, lower_inode,
419 ctx->param.lower_file,
423 - byte_offset_in_page));
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);
432 rc = ecryptfs_grab_and_map_lower_page(lower_page, NULL,
437 KERN_ERR, "Error attempting to grab and map "
438 "lower page with index [0x%.16x]; rc = [%d]\n",
448 * ecryptfs_encrypt_page
449 * @ctx: The context of the page
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.
459 * The actual operations performed on each page depends on the
460 * contents of the ecryptfs_page_crypt_context struct.
462 * Returns zero on success; negative on error
464 int ecryptfs_encrypt_page(struct ecryptfs_page_crypt_context *ctx)
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;
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
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);
492 ecryptfs_printk(KERN_ERR, "Error attempting to copy "
493 "page at index [0x%.16x]\n",
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,
510 - orig_byte_offset));
512 ecryptfs_printk(KERN_ERR, "Error attempting "
513 "to write out page; rc = [%d]"
517 page_state = ECRYPTFS_PAGE_STATE_WRITTEN;
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,
525 ecryptfs_printk(KERN_ERR, "Error attempting "
526 "to read in lower page with "
527 "index [0x%.16x]; rc = [%d]\n",
531 orig_byte_offset = lower_byte_offset;
532 prior_lower_page_idx = lower_page_idx;
533 page_state = ECRYPTFS_PAGE_STATE_READ;
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));
540 ecryptfs_printk(KERN_ERR, "Error attempting to "
541 "derive IV for extent [0x%.16x]; "
543 (base_extent + extent_offset), rc);
546 if (unlikely(ecryptfs_verbosity > 0)) {
547 ecryptfs_printk(KERN_DEBUG, "Encrypting extent "
549 ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
550 ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
552 ecryptfs_dump_hex((char *)
553 (page_address(ctx->page)
555 * crypt_stat->extent_size)), 8);
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]; "
563 (base_extent + extent_offset), rc);
564 if (unlikely(ecryptfs_verbosity > 0)) {
565 ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
567 ecryptfs_dump_hex((char *)(page_address(lower_page)
568 + lower_byte_offset), 8);
570 page_state = ECRYPTFS_PAGE_STATE_MODIFIED;
573 BUG_ON(orig_byte_offset != 0);
574 rc = ecryptfs_write_out_page(ctx, lower_page, lower_inode, 0,
576 + crypt_stat->extent_size));
578 ecryptfs_printk(KERN_ERR, "Error attempting to write out "
579 "page; rc = [%d]\n", rc);
587 * ecryptfs_decrypt_page
588 * @file: The ecryptfs file
589 * @page: The page in ecryptfs to decrypt
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.
599 * Returns zero on success; negative on error
601 int ecryptfs_decrypt_page(struct file *file, struct page *page)
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;
614 int num_extents_per_page;
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);
623 ecryptfs_printk(KERN_ERR, "Error attempting to copy "
624 "page at index [0x%.16x]\n",
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,
632 if (!lower_page_virt) {
634 ecryptfs_printk(KERN_ERR, "Error getting page for encrypted "
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,
649 ecryptfs_printk(KERN_ERR, "Error reading "
650 "lower encrypted page; rc = "
654 prior_lower_page_idx = lower_page_idx;
655 page_state = ECRYPTFS_PAGE_STATE_READ;
657 rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
658 (base_extent + extent_offset));
660 ecryptfs_printk(KERN_ERR, "Error attempting to "
661 "derive IV for extent [0x%.16x]; rc = "
663 (base_extent + extent_offset), rc);
666 if (unlikely(ecryptfs_verbosity > 0)) {
667 ecryptfs_printk(KERN_DEBUG, "Decrypting extent "
669 ecryptfs_dump_hex(extent_iv, crypt_stat->iv_bytes);
670 ecryptfs_printk(KERN_DEBUG, "First 8 bytes before "
672 ecryptfs_dump_hex((lower_page_virt + byte_offset), 8);
674 rc = ecryptfs_decrypt_page_offset(crypt_stat, page,
676 * crypt_stat->extent_size),
677 lower_page, byte_offset,
678 crypt_stat->extent_size,
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));
687 if (unlikely(ecryptfs_verbosity > 0)) {
688 ecryptfs_printk(KERN_DEBUG, "First 8 bytes after "
690 ecryptfs_dump_hex((char *)(page_address(page)
697 kmem_cache_free(ecryptfs_lower_page_cache, lower_page_virt);
702 * decrypt_scatterlist
704 * Returns the number of bytes decrypted; negative value on error
706 static int decrypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
707 struct scatterlist *dest_sg,
708 struct scatterlist *src_sg, int size,
711 struct blkcipher_desc desc = {
712 .tfm = crypt_stat->tfm,
714 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
718 /* Consider doing this once, when the file is opened */
719 mutex_lock(&crypt_stat->cs_tfm_mutex);
720 rc = crypto_blkcipher_setkey(crypt_stat->tfm, crypt_stat->key,
721 crypt_stat->key_size);
723 ecryptfs_printk(KERN_ERR, "Error setting key; rc = [%d]\n",
725 mutex_unlock(&crypt_stat->cs_tfm_mutex);
729 ecryptfs_printk(KERN_DEBUG, "Decrypting [%d] bytes.\n", size);
730 rc = crypto_blkcipher_decrypt_iv(&desc, dest_sg, src_sg, size);
731 mutex_unlock(&crypt_stat->cs_tfm_mutex);
733 ecryptfs_printk(KERN_ERR, "Error decrypting; rc = [%d]\n",
743 * ecryptfs_encrypt_page_offset
745 * Returns the number of bytes encrypted
748 ecryptfs_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,
753 struct scatterlist src_sg, dst_sg;
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);
765 * ecryptfs_decrypt_page_offset
767 * Returns the number of bytes decrypted
770 ecryptfs_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,
775 struct scatterlist src_sg, dst_sg;
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);
786 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4
789 * ecryptfs_init_crypt_ctx
790 * @crypt_stat: Uninitilized crypt stats structure
792 * Initialize the crypto context.
794 * TODO: Performance: Keep a cache of initialized cipher contexts;
795 * only init if needed
797 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
802 if (!crypt_stat->cipher) {
803 ecryptfs_printk(KERN_ERR, "No cipher specified\n");
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) {
815 mutex_lock(&crypt_stat->cs_tfm_mutex);
816 rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
817 crypt_stat->cipher, "cbc");
820 crypt_stat->tfm = crypto_alloc_blkcipher(full_alg_name, 0,
822 kfree(full_alg_name);
823 if (!crypt_stat->tfm) {
824 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
825 "Error initializing cipher [%s]\n",
827 mutex_unlock(&crypt_stat->cs_tfm_mutex);
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);
839 static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
843 crypt_stat->extent_mask = 0xFFFFFFFF;
844 crypt_stat->extent_shift = 0;
845 if (crypt_stat->extent_size == 0)
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++;
855 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
857 /* Default values; may be overwritten as we are parsing the
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;
866 crypt_stat->header_extent_size = PAGE_CACHE_SIZE;
867 crypt_stat->num_header_extents_at_front = 1;
871 * ecryptfs_compute_root_iv
874 * On error, sets the root IV to all 0's.
876 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
879 char dst[MD5_DIGEST_SIZE];
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)) {
885 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
886 "cannot generate root IV\n");
889 rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
890 crypt_stat->key_size);
892 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
893 "MD5 while generating root IV\n");
896 memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
899 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
900 ECRYPTFS_SET_FLAG(crypt_stat->flags,
901 ECRYPTFS_SECURITY_WARNING);
906 static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
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);
919 * ecryptfs_set_default_crypt_stat_vals
922 * Default values in the event that policy does not override them.
924 static void ecryptfs_set_default_crypt_stat_vals(
925 struct ecryptfs_crypt_stat *crypt_stat,
926 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
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;
937 * ecryptfs_new_file_context
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.
953 * Returns zero on success; non-zero otherwise
955 /* Associate an authentication token(s) with the file */
956 int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry)
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;
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);
977 strlen(mount_crypt_stat->global_default_cipher_name);
978 memcpy(crypt_stat->cipher,
979 mount_crypt_stat->global_default_cipher_name,
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);
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
991 rc = ecryptfs_init_crypt_ctx(crypt_stat);
993 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
994 "context for cipher [%s]: rc = [%d]\n",
995 crypt_stat->cipher, rc);
1000 * contains_ecryptfs_marker - check for the ecryptfs marker
1001 * @data: The data block in which to check
1003 * Returns one if marker found; zero if not found
1005 int contains_ecryptfs_marker(char *data)
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)
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));
1023 struct ecryptfs_flag_map_elem {
1028 /* Add support for additional flags by adding elements here. */
1029 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
1030 {0x00000001, ECRYPTFS_ENABLE_HMAC},
1031 {0x00000002, ECRYPTFS_ENCRYPTED}
1035 * ecryptfs_process_flags
1037 * @page_virt: Source data to be parsed
1038 * @bytes_read: Updated with the number of bytes read
1040 * Returns zero on success; non-zero if the flag set is invalid
1042 static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
1043 char *page_virt, int *bytes_read)
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);
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);
1066 * write_ecryptfs_marker
1067 * @page_virt: The pointer to in a page to begin writing the marker
1068 * @written: Number of bytes written
1070 * Marker = 0x3c81b7f5
1072 static void write_ecryptfs_marker(char *page_virt, size_t *written)
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;
1087 write_ecryptfs_flags(char *page_virt, struct ecryptfs_crypt_stat *crypt_stat,
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);
1105 struct ecryptfs_cipher_code_str_map_elem {
1106 char cipher_str[16];
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. */
1113 static struct ecryptfs_cipher_code_str_map_elem
1114 ecryptfs_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}
1126 * ecryptfs_code_for_cipher_string
1127 * @str: The string representing the cipher name
1129 * Returns zero on no match, or the cipher code on match
1131 u16 ecryptfs_code_for_cipher_string(struct ecryptfs_crypt_stat *crypt_stat)
1135 struct ecryptfs_cipher_code_str_map_elem *map =
1136 ecryptfs_cipher_code_str_map;
1138 if (strcmp(crypt_stat->cipher, "aes") == 0) {
1139 switch (crypt_stat->key_size) {
1141 code = RFC2440_CIPHER_AES_128;
1144 code = RFC2440_CIPHER_AES_192;
1147 code = RFC2440_CIPHER_AES_256;
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;
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
1164 * Returns zero on success
1166 int ecryptfs_cipher_code_to_string(char *str, u16 cipher_code)
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);
1184 * ecryptfs_read_header_region
1189 * Returns zero on success; non-zero otherwise
1191 int ecryptfs_read_header_region(char *data, struct dentry *dentry,
1192 struct vfsmount *mnt)
1194 struct file *lower_file;
1198 if ((rc = ecryptfs_open_lower_file(&lower_file, dentry, mnt,
1201 "Error opening lower_file to read header region\n");
1204 lower_file->f_pos = 0;
1207 /* For releases 0.1 and 0.2, all of the header information
1208 * fits in the first data extent-sized region. */
1209 rc = lower_file->f_op->read(lower_file, (char __user *)data,
1210 ECRYPTFS_DEFAULT_EXTENT_SIZE, &lower_file->f_pos);
1212 if ((rc = ecryptfs_close_lower_file(lower_file))) {
1213 printk(KERN_ERR "Error closing lower_file\n");
1222 write_header_metadata(char *virt, struct ecryptfs_crypt_stat *crypt_stat,
1225 u32 header_extent_size;
1226 u16 num_header_extents_at_front;
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);
1234 num_header_extents_at_front = cpu_to_be16(num_header_extents_at_front);
1235 memcpy(virt, &num_header_extents_at_front, 2);
1239 struct kmem_cache *ecryptfs_header_cache_0;
1240 struct kmem_cache *ecryptfs_header_cache_1;
1241 struct kmem_cache *ecryptfs_header_cache_2;
1244 * ecryptfs_write_headers_virt
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
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
1263 * Octet 26: Begin RFC 2440 authentication token packet set
1265 * Lower data (CBC encrypted)
1267 * Lower data (CBC encrypted)
1270 * Returns zero on success
1272 int ecryptfs_write_headers_virt(char *page_virt,
1273 struct ecryptfs_crypt_stat *crypt_stat,
1274 struct dentry *ecryptfs_dentry)
1280 offset = ECRYPTFS_FILE_SIZE_BYTES;
1281 write_ecryptfs_marker((page_virt + offset), &written);
1283 write_ecryptfs_flags((page_virt + offset), crypt_stat, &written);
1285 write_header_metadata((page_virt + offset), crypt_stat, &written);
1287 rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1288 ecryptfs_dentry, &written,
1289 PAGE_CACHE_SIZE - offset);
1291 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1292 "set; rc = [%d]\n", rc);
1297 * ecryptfs_write_headers
1298 * @lower_file: The lower file struct, which was returned from dentry_open
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.
1306 * Returns zero on success; non-zero on error
1308 int ecryptfs_write_headers(struct dentry *ecryptfs_dentry,
1309 struct file *lower_file)
1312 struct ecryptfs_crypt_stat *crypt_stat;
1314 int current_header_page;
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");
1331 ecryptfs_printk(KERN_WARNING,
1332 "Called with crypt_stat->encrypted == 0\n");
1335 /* Released in this function */
1336 page_virt = kmem_cache_alloc(ecryptfs_header_cache_0, SLAB_USER);
1338 ecryptfs_printk(KERN_ERR, "Out of memory\n");
1342 memset(page_virt, 0, PAGE_CACHE_SIZE);
1343 rc = ecryptfs_write_headers_virt(page_virt, crypt_stat,
1346 ecryptfs_printk(KERN_ERR, "Error whilst writing headers\n");
1347 memset(page_virt, 0, PAGE_CACHE_SIZE);
1350 ecryptfs_printk(KERN_DEBUG,
1351 "Writing key packet set to underlying file\n");
1352 lower_file->f_pos = 0;
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)
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++;
1374 ecryptfs_printk(KERN_DEBUG,
1375 "Done writing key packet set to underlying file.\n");
1377 kmem_cache_free(ecryptfs_header_cache_0, page_virt);
1382 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1383 char *virt, int *bytes_read)
1386 u32 header_extent_size;
1387 u16 num_header_extents_at_front;
1389 memcpy(&header_extent_size, virt, 4);
1390 header_extent_size = be32_to_cpu(header_extent_size);
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;
1398 if ((crypt_stat->header_extent_size
1399 * crypt_stat->num_header_extents_at_front)
1400 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) {
1402 ecryptfs_printk(KERN_WARNING, "Invalid header extent size: "
1403 "[%d]\n", crypt_stat->header_extent_size);
1409 * set_default_header_data
1411 * For version 0 file format; this function is only for backwards
1412 * compatibility for files created with the prior versions of
1415 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1417 crypt_stat->header_extent_size = 4096;
1418 crypt_stat->num_header_extents_at_front = 1;
1422 * ecryptfs_read_headers_virt
1424 * Read/parse the header data. The header format is detailed in the
1425 * comment block for the ecryptfs_write_headers_virt() function.
1427 * Returns zero on success
1429 static int ecryptfs_read_headers_virt(char *page_virt,
1430 struct ecryptfs_crypt_stat *crypt_stat,
1431 struct dentry *ecryptfs_dentry)
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);
1446 offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1447 rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1450 ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
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);
1462 offset += bytes_read;
1463 if (crypt_stat->file_version >= 1) {
1464 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1467 ecryptfs_printk(KERN_WARNING, "Error reading header "
1468 "metadata; rc = [%d]\n", rc);
1470 offset += bytes_read;
1472 set_default_header_data(crypt_stat);
1473 rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1480 * ecryptfs_read_headers
1482 * Returns zero if valid headers found and parsed; non-zero otherwise
1484 int ecryptfs_read_headers(struct dentry *ecryptfs_dentry,
1485 struct file *lower_file)
1488 char *page_virt = NULL;
1491 struct ecryptfs_crypt_stat *crypt_stat =
1492 &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
1494 /* Read the first page from the underlying file */
1495 page_virt = kmem_cache_alloc(ecryptfs_header_cache_1, SLAB_USER);
1498 ecryptfs_printk(KERN_ERR, "Unable to allocate page_virt\n");
1501 lower_file->f_pos = 0;
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);
1509 if (bytes_read != ECRYPTFS_DEFAULT_EXTENT_SIZE) {
1513 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1516 ecryptfs_printk(KERN_DEBUG, "Valid eCryptfs headers not "
1522 memset(page_virt, 0, PAGE_CACHE_SIZE);
1523 kmem_cache_free(ecryptfs_header_cache_1, page_virt);
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
1535 * Encrypts and encodes a filename into something that constitutes a
1536 * valid filename for a filesystem, with printable characters.
1538 * We assume that we have a properly initialized crypto context,
1539 * pointed to by crypt_stat->tfm.
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.
1547 * Returns the length of encoded filename; negative if error
1550 ecryptfs_encode_filename(struct ecryptfs_crypt_stat *crypt_stat,
1551 const char *name, int length, char **encoded_name)
1555 (*encoded_name) = kmalloc(length + 2, GFP_KERNEL);
1556 if (!(*encoded_name)) {
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';
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
1580 * Decodes and decrypts the filename.
1582 * We assume that we have a properly initialized crypto context,
1583 * pointed to by crypt_stat->tfm.
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.
1591 * Returns the length of decoded filename; negative if error
1594 ecryptfs_decode_filename(struct ecryptfs_crypt_stat *crypt_stat,
1595 const char *name, int length, char **decrypted_name)
1599 (*decrypted_name) = kmalloc(length + 2, GFP_KERNEL);
1600 if (!(*decrypted_name)) {
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
1621 * ecryptfs_process_cipher - Perform cipher initialization.
1622 * @key_tfm: Crypto context for key material, set by this function
1623 * @cipher_name: Name of the cipher
1624 * @key_size: Size of the key in bytes
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.
1631 ecryptfs_process_cipher(struct crypto_blkcipher **key_tfm, char *cipher_name,
1634 char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1635 char *full_alg_name;
1639 if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1641 printk(KERN_ERR "Requested key size is [%Zd] bytes; maximum "
1642 "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1645 rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
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);
1653 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1654 "[%s]; rc = [%d]\n", cipher_name, rc);
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);
1661 *key_size = alg->max_keysize;
1663 get_random_bytes(dummy_key, *key_size);
1664 rc = crypto_blkcipher_setkey(*key_tfm, dummy_key, *key_size);
1666 printk(KERN_ERR "Error attempting to set key of size [%Zd] for "
1667 "cipher [%s]; rc = [%d]\n", *key_size, cipher_name, rc);