2 * eCryptfs: Linux filesystem encryption layer
4 * Copyright (C) 1997-2004 Erez Zadok
5 * Copyright (C) 2001-2004 Stony Brook University
6 * Copyright (C) 2004-2007 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 (IS_ERR(crypt_stat->tfm)) {
824 rc = PTR_ERR(crypt_stat->tfm);
825 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
826 "Error initializing cipher [%s]\n",
828 mutex_unlock(&crypt_stat->cs_tfm_mutex);
831 crypto_blkcipher_set_flags(crypt_stat->tfm, CRYPTO_TFM_REQ_WEAK_KEY);
832 mutex_unlock(&crypt_stat->cs_tfm_mutex);
838 static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
842 crypt_stat->extent_mask = 0xFFFFFFFF;
843 crypt_stat->extent_shift = 0;
844 if (crypt_stat->extent_size == 0)
846 extent_size_tmp = crypt_stat->extent_size;
847 while ((extent_size_tmp & 0x01) == 0) {
848 extent_size_tmp >>= 1;
849 crypt_stat->extent_mask <<= 1;
850 crypt_stat->extent_shift++;
854 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
856 /* Default values; may be overwritten as we are parsing the
858 crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
859 set_extent_mask_and_shift(crypt_stat);
860 crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
861 if (PAGE_CACHE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) {
862 crypt_stat->header_extent_size =
863 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
865 crypt_stat->header_extent_size = PAGE_CACHE_SIZE;
866 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
867 crypt_stat->num_header_extents_at_front = 0;
869 crypt_stat->num_header_extents_at_front = 1;
873 * ecryptfs_compute_root_iv
876 * On error, sets the root IV to all 0's.
878 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
881 char dst[MD5_DIGEST_SIZE];
883 BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
884 BUG_ON(crypt_stat->iv_bytes <= 0);
885 if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID)) {
887 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
888 "cannot generate root IV\n");
891 rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
892 crypt_stat->key_size);
894 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
895 "MD5 while generating root IV\n");
898 memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
901 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
902 ECRYPTFS_SET_FLAG(crypt_stat->flags,
903 ECRYPTFS_SECURITY_WARNING);
908 static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
910 get_random_bytes(crypt_stat->key, crypt_stat->key_size);
911 ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
912 ecryptfs_compute_root_iv(crypt_stat);
913 if (unlikely(ecryptfs_verbosity > 0)) {
914 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
915 ecryptfs_dump_hex(crypt_stat->key,
916 crypt_stat->key_size);
921 * ecryptfs_copy_mount_wide_flags_to_inode_flags
923 * This function propagates the mount-wide flags to individual inode
926 static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
927 struct ecryptfs_crypt_stat *crypt_stat,
928 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
930 if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
931 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
932 if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
933 crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
937 * ecryptfs_set_default_crypt_stat_vals
940 * Default values in the event that policy does not override them.
942 static void ecryptfs_set_default_crypt_stat_vals(
943 struct ecryptfs_crypt_stat *crypt_stat,
944 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
946 ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
948 ecryptfs_set_default_sizes(crypt_stat);
949 strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
950 crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
951 ECRYPTFS_CLEAR_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
952 crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
953 crypt_stat->mount_crypt_stat = mount_crypt_stat;
957 * ecryptfs_new_file_context
960 * If the crypto context for the file has not yet been established,
961 * this is where we do that. Establishing a new crypto context
962 * involves the following decisions:
963 * - What cipher to use?
964 * - What set of authentication tokens to use?
965 * Here we just worry about getting enough information into the
966 * authentication tokens so that we know that they are available.
967 * We associate the available authentication tokens with the new file
968 * via the set of signatures in the crypt_stat struct. Later, when
969 * the headers are actually written out, we may again defer to
970 * userspace to perform the encryption of the session key; for the
971 * foreseeable future, this will be the case with public key packets.
973 * Returns zero on success; non-zero otherwise
975 /* Associate an authentication token(s) with the file */
976 int ecryptfs_new_file_context(struct dentry *ecryptfs_dentry)
979 struct ecryptfs_crypt_stat *crypt_stat =
980 &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
981 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
982 &ecryptfs_superblock_to_private(
983 ecryptfs_dentry->d_sb)->mount_crypt_stat;
986 ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
987 /* See if there are mount crypt options */
988 if (mount_crypt_stat->global_auth_tok) {
989 ecryptfs_printk(KERN_DEBUG, "Initializing context for new "
990 "file using mount_crypt_stat\n");
991 ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED);
992 ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
993 ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
995 memcpy(crypt_stat->keysigs[crypt_stat->num_keysigs++],
996 mount_crypt_stat->global_auth_tok_sig,
997 ECRYPTFS_SIG_SIZE_HEX);
999 strlen(mount_crypt_stat->global_default_cipher_name);
1000 memcpy(crypt_stat->cipher,
1001 mount_crypt_stat->global_default_cipher_name,
1003 crypt_stat->cipher[cipher_name_len] = '\0';
1004 crypt_stat->key_size =
1005 mount_crypt_stat->global_default_cipher_key_size;
1006 ecryptfs_generate_new_key(crypt_stat);
1008 /* We should not encounter this scenario since we
1009 * should detect lack of global_auth_tok at mount time
1010 * TODO: Applies to 0.1 release only; remove in future
1013 rc = ecryptfs_init_crypt_ctx(crypt_stat);
1015 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
1016 "context for cipher [%s]: rc = [%d]\n",
1017 crypt_stat->cipher, rc);
1022 * contains_ecryptfs_marker - check for the ecryptfs marker
1023 * @data: The data block in which to check
1025 * Returns one if marker found; zero if not found
1027 static int contains_ecryptfs_marker(char *data)
1031 memcpy(&m_1, data, 4);
1032 m_1 = be32_to_cpu(m_1);
1033 memcpy(&m_2, (data + 4), 4);
1034 m_2 = be32_to_cpu(m_2);
1035 if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
1037 ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
1038 "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
1039 MAGIC_ECRYPTFS_MARKER);
1040 ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
1041 "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
1045 struct ecryptfs_flag_map_elem {
1050 /* Add support for additional flags by adding elements here. */
1051 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
1052 {0x00000001, ECRYPTFS_ENABLE_HMAC},
1053 {0x00000002, ECRYPTFS_ENCRYPTED},
1054 {0x00000004, ECRYPTFS_METADATA_IN_XATTR}
1058 * ecryptfs_process_flags
1060 * @page_virt: Source data to be parsed
1061 * @bytes_read: Updated with the number of bytes read
1063 * Returns zero on success; non-zero if the flag set is invalid
1065 static int ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
1066 char *page_virt, int *bytes_read)
1072 memcpy(&flags, page_virt, 4);
1073 flags = be32_to_cpu(flags);
1074 for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1075 / sizeof(struct ecryptfs_flag_map_elem))); i++)
1076 if (flags & ecryptfs_flag_map[i].file_flag) {
1077 ECRYPTFS_SET_FLAG(crypt_stat->flags,
1078 ecryptfs_flag_map[i].local_flag);
1080 ECRYPTFS_CLEAR_FLAG(crypt_stat->flags,
1081 ecryptfs_flag_map[i].local_flag);
1082 /* Version is in top 8 bits of the 32-bit flag vector */
1083 crypt_stat->file_version = ((flags >> 24) & 0xFF);
1089 * write_ecryptfs_marker
1090 * @page_virt: The pointer to in a page to begin writing the marker
1091 * @written: Number of bytes written
1093 * Marker = 0x3c81b7f5
1095 static void write_ecryptfs_marker(char *page_virt, size_t *written)
1099 get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1100 m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
1101 m_1 = cpu_to_be32(m_1);
1102 memcpy(page_virt, &m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1103 m_2 = cpu_to_be32(m_2);
1104 memcpy(page_virt + (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2), &m_2,
1105 (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
1106 (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1110 write_ecryptfs_flags(char *page_virt, struct ecryptfs_crypt_stat *crypt_stat,
1116 for (i = 0; i < ((sizeof(ecryptfs_flag_map)
1117 / sizeof(struct ecryptfs_flag_map_elem))); i++)
1118 if (ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
1119 ecryptfs_flag_map[i].local_flag))
1120 flags |= ecryptfs_flag_map[i].file_flag;
1121 /* Version is in top 8 bits of the 32-bit flag vector */
1122 flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
1123 flags = cpu_to_be32(flags);
1124 memcpy(page_virt, &flags, 4);
1128 struct ecryptfs_cipher_code_str_map_elem {
1129 char cipher_str[16];
1133 /* Add support for additional ciphers by adding elements here. The
1134 * cipher_code is whatever OpenPGP applicatoins use to identify the
1135 * ciphers. List in order of probability. */
1136 static struct ecryptfs_cipher_code_str_map_elem
1137 ecryptfs_cipher_code_str_map[] = {
1138 {"aes",RFC2440_CIPHER_AES_128 },
1139 {"blowfish", RFC2440_CIPHER_BLOWFISH},
1140 {"des3_ede", RFC2440_CIPHER_DES3_EDE},
1141 {"cast5", RFC2440_CIPHER_CAST_5},
1142 {"twofish", RFC2440_CIPHER_TWOFISH},
1143 {"cast6", RFC2440_CIPHER_CAST_6},
1144 {"aes", RFC2440_CIPHER_AES_192},
1145 {"aes", RFC2440_CIPHER_AES_256}
1149 * ecryptfs_code_for_cipher_string
1150 * @str: The string representing the cipher name
1152 * Returns zero on no match, or the cipher code on match
1154 u16 ecryptfs_code_for_cipher_string(struct ecryptfs_crypt_stat *crypt_stat)
1158 struct ecryptfs_cipher_code_str_map_elem *map =
1159 ecryptfs_cipher_code_str_map;
1161 if (strcmp(crypt_stat->cipher, "aes") == 0) {
1162 switch (crypt_stat->key_size) {
1164 code = RFC2440_CIPHER_AES_128;
1167 code = RFC2440_CIPHER_AES_192;
1170 code = RFC2440_CIPHER_AES_256;
1173 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1174 if (strcmp(crypt_stat->cipher, map[i].cipher_str) == 0){
1175 code = map[i].cipher_code;
1183 * ecryptfs_cipher_code_to_string
1184 * @str: Destination to write out the cipher name
1185 * @cipher_code: The code to convert to cipher name string
1187 * Returns zero on success
1189 int ecryptfs_cipher_code_to_string(char *str, u16 cipher_code)
1195 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
1196 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
1197 strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
1198 if (str[0] == '\0') {
1199 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
1200 "[%d]\n", cipher_code);
1207 * ecryptfs_read_header_region
1212 * Returns zero on success; non-zero otherwise
1214 static int ecryptfs_read_header_region(char *data, struct dentry *dentry,
1215 struct vfsmount *mnt)
1217 struct file *lower_file;
1221 if ((rc = ecryptfs_open_lower_file(&lower_file, dentry, mnt,
1224 "Error opening lower_file to read header region\n");
1227 lower_file->f_pos = 0;
1230 /* For releases 0.1 and 0.2, all of the header information
1231 * fits in the first data extent-sized region. */
1232 rc = lower_file->f_op->read(lower_file, (char __user *)data,
1233 ECRYPTFS_DEFAULT_EXTENT_SIZE, &lower_file->f_pos);
1235 if ((rc = ecryptfs_close_lower_file(lower_file))) {
1236 printk(KERN_ERR "Error closing lower_file\n");
1244 int ecryptfs_read_and_validate_header_region(char *data, struct dentry *dentry,
1245 struct vfsmount *mnt)
1249 rc = ecryptfs_read_header_region(data, dentry, mnt);
1252 if (!contains_ecryptfs_marker(data + ECRYPTFS_FILE_SIZE_BYTES))
1260 write_header_metadata(char *virt, struct ecryptfs_crypt_stat *crypt_stat,
1263 u32 header_extent_size;
1264 u16 num_header_extents_at_front;
1266 header_extent_size = (u32)crypt_stat->header_extent_size;
1267 num_header_extents_at_front =
1268 (u16)crypt_stat->num_header_extents_at_front;
1269 header_extent_size = cpu_to_be32(header_extent_size);
1270 memcpy(virt, &header_extent_size, 4);
1272 num_header_extents_at_front = cpu_to_be16(num_header_extents_at_front);
1273 memcpy(virt, &num_header_extents_at_front, 2);
1277 struct kmem_cache *ecryptfs_header_cache_0;
1278 struct kmem_cache *ecryptfs_header_cache_1;
1279 struct kmem_cache *ecryptfs_header_cache_2;
1282 * ecryptfs_write_headers_virt
1290 * Octets 0-7: Unencrypted file size (big-endian)
1291 * Octets 8-15: eCryptfs special marker
1292 * Octets 16-19: Flags
1293 * Octet 16: File format version number (between 0 and 255)
1294 * Octets 17-18: Reserved
1295 * Octet 19: Bit 1 (lsb): Reserved
1297 * Bits 3-8: Reserved
1298 * Octets 20-23: Header extent size (big-endian)
1299 * Octets 24-25: Number of header extents at front of file
1301 * Octet 26: Begin RFC 2440 authentication token packet set
1303 * Lower data (CBC encrypted)
1305 * Lower data (CBC encrypted)
1308 * Returns zero on success
1310 static int ecryptfs_write_headers_virt(char *page_virt, size_t *size,
1311 struct ecryptfs_crypt_stat *crypt_stat,
1312 struct dentry *ecryptfs_dentry)
1318 offset = ECRYPTFS_FILE_SIZE_BYTES;
1319 write_ecryptfs_marker((page_virt + offset), &written);
1321 write_ecryptfs_flags((page_virt + offset), crypt_stat, &written);
1323 write_header_metadata((page_virt + offset), crypt_stat, &written);
1325 rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1326 ecryptfs_dentry, &written,
1327 PAGE_CACHE_SIZE - offset);
1329 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1330 "set; rc = [%d]\n", rc);
1338 static int ecryptfs_write_metadata_to_contents(struct ecryptfs_crypt_stat *crypt_stat,
1339 struct file *lower_file,
1343 int current_header_page;
1346 lower_file->f_pos = 0;
1349 lower_file->f_op->write(lower_file, (char __user *)page_virt,
1350 PAGE_CACHE_SIZE, &lower_file->f_pos);
1351 header_pages = ((crypt_stat->header_extent_size
1352 * crypt_stat->num_header_extents_at_front)
1354 memset(page_virt, 0, PAGE_CACHE_SIZE);
1355 current_header_page = 1;
1356 while (current_header_page < header_pages) {
1357 lower_file->f_op->write(lower_file, (char __user *)page_virt,
1358 PAGE_CACHE_SIZE, &lower_file->f_pos);
1359 current_header_page++;
1365 static int ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1366 struct ecryptfs_crypt_stat *crypt_stat,
1367 char *page_virt, size_t size)
1371 rc = ecryptfs_setxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME, page_virt,
1377 * ecryptfs_write_metadata
1378 * @lower_file: The lower file struct, which was returned from dentry_open
1380 * Write the file headers out. This will likely involve a userspace
1381 * callout, in which the session key is encrypted with one or more
1382 * public keys and/or the passphrase necessary to do the encryption is
1383 * retrieved via a prompt. Exactly what happens at this point should
1384 * be policy-dependent.
1386 * Returns zero on success; non-zero on error
1388 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1389 struct file *lower_file)
1391 struct ecryptfs_crypt_stat *crypt_stat;
1396 crypt_stat = &ecryptfs_inode_to_private(
1397 ecryptfs_dentry->d_inode)->crypt_stat;
1398 if (likely(ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
1399 ECRYPTFS_ENCRYPTED))) {
1400 if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
1401 ECRYPTFS_KEY_VALID)) {
1402 ecryptfs_printk(KERN_DEBUG, "Key is "
1403 "invalid; bailing out\n");
1409 ecryptfs_printk(KERN_WARNING,
1410 "Called with crypt_stat->encrypted == 0\n");
1413 /* Released in this function */
1414 page_virt = kmem_cache_zalloc(ecryptfs_header_cache_0, GFP_USER);
1416 ecryptfs_printk(KERN_ERR, "Out of memory\n");
1420 rc = ecryptfs_write_headers_virt(page_virt, &size, crypt_stat,
1423 ecryptfs_printk(KERN_ERR, "Error whilst writing headers\n");
1424 memset(page_virt, 0, PAGE_CACHE_SIZE);
1427 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1428 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry,
1429 crypt_stat, page_virt,
1432 rc = ecryptfs_write_metadata_to_contents(crypt_stat, lower_file,
1435 printk(KERN_ERR "Error writing metadata out to lower file; "
1440 kmem_cache_free(ecryptfs_header_cache_0, page_virt);
1445 #define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1446 #define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1447 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1448 char *virt, int *bytes_read,
1449 int validate_header_size)
1452 u32 header_extent_size;
1453 u16 num_header_extents_at_front;
1455 memcpy(&header_extent_size, virt, 4);
1456 header_extent_size = be32_to_cpu(header_extent_size);
1458 memcpy(&num_header_extents_at_front, virt, 2);
1459 num_header_extents_at_front = be16_to_cpu(num_header_extents_at_front);
1460 crypt_stat->header_extent_size = (int)header_extent_size;
1461 crypt_stat->num_header_extents_at_front =
1462 (int)num_header_extents_at_front;
1464 if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1465 && ((crypt_stat->header_extent_size
1466 * crypt_stat->num_header_extents_at_front)
1467 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1469 ecryptfs_printk(KERN_WARNING, "Invalid header extent size: "
1470 "[%d]\n", crypt_stat->header_extent_size);
1476 * set_default_header_data
1478 * For version 0 file format; this function is only for backwards
1479 * compatibility for files created with the prior versions of
1482 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1484 crypt_stat->header_extent_size = 4096;
1485 crypt_stat->num_header_extents_at_front = 1;
1489 * ecryptfs_read_headers_virt
1491 * Read/parse the header data. The header format is detailed in the
1492 * comment block for the ecryptfs_write_headers_virt() function.
1494 * Returns zero on success
1496 static int ecryptfs_read_headers_virt(char *page_virt,
1497 struct ecryptfs_crypt_stat *crypt_stat,
1498 struct dentry *ecryptfs_dentry,
1499 int validate_header_size)
1505 ecryptfs_set_default_sizes(crypt_stat);
1506 crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1507 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1508 offset = ECRYPTFS_FILE_SIZE_BYTES;
1509 rc = contains_ecryptfs_marker(page_virt + offset);
1514 offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1515 rc = ecryptfs_process_flags(crypt_stat, (page_virt + offset),
1518 ecryptfs_printk(KERN_WARNING, "Error processing flags\n");
1521 if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1522 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1523 "file version [%d] is supported by this "
1524 "version of eCryptfs\n",
1525 crypt_stat->file_version,
1526 ECRYPTFS_SUPPORTED_FILE_VERSION);
1530 offset += bytes_read;
1531 if (crypt_stat->file_version >= 1) {
1532 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1533 &bytes_read, validate_header_size);
1535 ecryptfs_printk(KERN_WARNING, "Error reading header "
1536 "metadata; rc = [%d]\n", rc);
1538 offset += bytes_read;
1540 set_default_header_data(crypt_stat);
1541 rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1548 * ecryptfs_read_xattr_region
1550 * Attempts to read the crypto metadata from the extended attribute
1551 * region of the lower file.
1553 int ecryptfs_read_xattr_region(char *page_virt, struct dentry *ecryptfs_dentry)
1558 size = ecryptfs_getxattr(ecryptfs_dentry, ECRYPTFS_XATTR_NAME,
1559 page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1561 printk(KERN_DEBUG "Error attempting to read the [%s] "
1562 "xattr from the lower file; return value = [%zd]\n",
1563 ECRYPTFS_XATTR_NAME, size);
1571 int ecryptfs_read_and_validate_xattr_region(char *page_virt,
1572 struct dentry *ecryptfs_dentry)
1576 rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_dentry);
1579 if (!contains_ecryptfs_marker(page_virt + ECRYPTFS_FILE_SIZE_BYTES)) {
1580 printk(KERN_WARNING "Valid data found in [%s] xattr, but "
1581 "the marker is invalid\n", ECRYPTFS_XATTR_NAME);
1589 * ecryptfs_read_metadata
1591 * Common entry point for reading file metadata. From here, we could
1592 * retrieve the header information from the header region of the file,
1593 * the xattr region of the file, or some other repostory that is
1594 * stored separately from the file itself. The current implementation
1595 * supports retrieving the metadata information from the file contents
1596 * and from the xattr region.
1598 * Returns zero if valid headers found and parsed; non-zero otherwise
1600 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry,
1601 struct file *lower_file)
1604 char *page_virt = NULL;
1607 struct ecryptfs_crypt_stat *crypt_stat =
1608 &ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
1610 /* Read the first page from the underlying file */
1611 page_virt = kmem_cache_alloc(ecryptfs_header_cache_1, GFP_USER);
1614 ecryptfs_printk(KERN_ERR, "Unable to allocate page_virt\n");
1617 lower_file->f_pos = 0;
1620 bytes_read = lower_file->f_op->read(lower_file,
1621 (char __user *)page_virt,
1622 ECRYPTFS_DEFAULT_EXTENT_SIZE,
1623 &lower_file->f_pos);
1625 if (bytes_read != ECRYPTFS_DEFAULT_EXTENT_SIZE) {
1629 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1631 ECRYPTFS_VALIDATE_HEADER_SIZE);
1633 rc = ecryptfs_read_xattr_region(page_virt,
1636 printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1637 "file header region or xattr region\n");
1641 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1643 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1645 printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1646 "file xattr region either\n");
1649 if (crypt_stat->mount_crypt_stat->flags
1650 & ECRYPTFS_XATTR_METADATA_ENABLED) {
1651 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1653 printk(KERN_WARNING "Attempt to access file with "
1654 "crypto metadata only in the extended attribute "
1655 "region, but eCryptfs was mounted without "
1656 "xattr support enabled. eCryptfs will not treat "
1657 "this like an encrypted file.\n");
1663 memset(page_virt, 0, PAGE_CACHE_SIZE);
1664 kmem_cache_free(ecryptfs_header_cache_1, page_virt);
1670 * ecryptfs_encode_filename - converts a plaintext file name to cipher text
1671 * @crypt_stat: The crypt_stat struct associated with the file anem to encode
1672 * @name: The plaintext name
1673 * @length: The length of the plaintext
1674 * @encoded_name: The encypted name
1676 * Encrypts and encodes a filename into something that constitutes a
1677 * valid filename for a filesystem, with printable characters.
1679 * We assume that we have a properly initialized crypto context,
1680 * pointed to by crypt_stat->tfm.
1682 * TODO: Implement filename decoding and decryption here, in place of
1683 * memcpy. We are keeping the framework around for now to (1)
1684 * facilitate testing of the components needed to implement filename
1685 * encryption and (2) to provide a code base from which other
1686 * developers in the community can easily implement this feature.
1688 * Returns the length of encoded filename; negative if error
1691 ecryptfs_encode_filename(struct ecryptfs_crypt_stat *crypt_stat,
1692 const char *name, int length, char **encoded_name)
1696 (*encoded_name) = kmalloc(length + 2, GFP_KERNEL);
1697 if (!(*encoded_name)) {
1701 /* TODO: Filename encryption is a scheduled feature for a
1702 * future version of eCryptfs. This function is here only for
1703 * the purpose of providing a framework for other developers
1704 * to easily implement filename encryption. Hint: Replace this
1705 * memcpy() with a call to encrypt and encode the
1706 * filename, the set the length accordingly. */
1707 memcpy((void *)(*encoded_name), (void *)name, length);
1708 (*encoded_name)[length] = '\0';
1715 * ecryptfs_decode_filename - converts the cipher text name to plaintext
1716 * @crypt_stat: The crypt_stat struct associated with the file
1717 * @name: The filename in cipher text
1718 * @length: The length of the cipher text name
1719 * @decrypted_name: The plaintext name
1721 * Decodes and decrypts the filename.
1723 * We assume that we have a properly initialized crypto context,
1724 * pointed to by crypt_stat->tfm.
1726 * TODO: Implement filename decoding and decryption here, in place of
1727 * memcpy. We are keeping the framework around for now to (1)
1728 * facilitate testing of the components needed to implement filename
1729 * encryption and (2) to provide a code base from which other
1730 * developers in the community can easily implement this feature.
1732 * Returns the length of decoded filename; negative if error
1735 ecryptfs_decode_filename(struct ecryptfs_crypt_stat *crypt_stat,
1736 const char *name, int length, char **decrypted_name)
1740 (*decrypted_name) = kmalloc(length + 2, GFP_KERNEL);
1741 if (!(*decrypted_name)) {
1745 /* TODO: Filename encryption is a scheduled feature for a
1746 * future version of eCryptfs. This function is here only for
1747 * the purpose of providing a framework for other developers
1748 * to easily implement filename encryption. Hint: Replace this
1749 * memcpy() with a call to decode and decrypt the
1750 * filename, the set the length accordingly. */
1751 memcpy((void *)(*decrypted_name), (void *)name, length);
1752 (*decrypted_name)[length + 1] = '\0'; /* Only for convenience
1753 * in printing out the
1762 * ecryptfs_process_cipher - Perform cipher initialization.
1763 * @key_tfm: Crypto context for key material, set by this function
1764 * @cipher_name: Name of the cipher
1765 * @key_size: Size of the key in bytes
1767 * Returns zero on success. Any crypto_tfm structs allocated here
1768 * should be released by other functions, such as on a superblock put
1769 * event, regardless of whether this function succeeds for fails.
1772 ecryptfs_process_cipher(struct crypto_blkcipher **key_tfm, char *cipher_name,
1775 char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1776 char *full_alg_name;
1780 if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1782 printk(KERN_ERR "Requested key size is [%Zd] bytes; maximum "
1783 "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1786 rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1790 *key_tfm = crypto_alloc_blkcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1791 kfree(full_alg_name);
1792 if (IS_ERR(*key_tfm)) {
1793 rc = PTR_ERR(*key_tfm);
1794 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1795 "[%s]; rc = [%d]\n", cipher_name, rc);
1798 crypto_blkcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1799 if (*key_size == 0) {
1800 struct blkcipher_alg *alg = crypto_blkcipher_alg(*key_tfm);
1802 *key_size = alg->max_keysize;
1804 get_random_bytes(dummy_key, *key_size);
1805 rc = crypto_blkcipher_setkey(*key_tfm, dummy_key, *key_size);
1807 printk(KERN_ERR "Error attempting to set key of size [%Zd] for "
1808 "cipher [%s]; rc = [%d]\n", *key_size, cipher_name, rc);