1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * eCryptfs: Linux filesystem encryption layer
4 *
5 * Copyright (C) 1997-2004 Erez Zadok
6 * Copyright (C) 2001-2004 Stony Brook University
7 * Copyright (C) 2004-2007 International Business Machines Corp.
8 * Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
9 * Michael C. Thompson <mcthomps@us.ibm.com>
10 */
11
12 #include <crypto/hash.h>
13 #include <crypto/skcipher.h>
14 #include <linux/fs.h>
15 #include <linux/mount.h>
16 #include <linux/pagemap.h>
17 #include <linux/random.h>
18 #include <linux/compiler.h>
19 #include <linux/key.h>
20 #include <linux/namei.h>
21 #include <linux/file.h>
22 #include <linux/scatterlist.h>
23 #include <linux/slab.h>
24 #include <asm/unaligned.h>
25 #include <linux/kernel.h>
26 #include <linux/xattr.h>
27 #include "ecryptfs_kernel.h"
28
29 #define DECRYPT 0
30 #define ENCRYPT 1
31
32 /**
33 * ecryptfs_from_hex
34 * @dst: Buffer to take the bytes from src hex; must be at least of
35 * size (src_size / 2)
36 * @src: Buffer to be converted from a hex string representation to raw value
37 * @dst_size: size of dst buffer, or number of hex characters pairs to convert
38 */
39 void ecryptfs_from_hex(char *dst, char *src, int dst_size)
40 {
41 int x;
42 char tmp[3] = { 0, };
43
44 for (x = 0; x < dst_size; x++) {
45 tmp[0] = src[x * 2];
46 tmp[1] = src[x * 2 + 1];
47 dst[x] = (unsigned char)simple_strtol(tmp, NULL, 16);
48 }
49 }
50
51 /**
52 * ecryptfs_calculate_md5 - calculates the md5 of @src
53 * @dst: Pointer to 16 bytes of allocated memory
54 * @crypt_stat: Pointer to crypt_stat struct for the current inode
55 * @src: Data to be md5'd
56 * @len: Length of @src
57 *
58 * Uses the allocated crypto context that crypt_stat references to
59 * generate the MD5 sum of the contents of src.
60 */
61 static int ecryptfs_calculate_md5(char *dst,
62 struct ecryptfs_crypt_stat *crypt_stat,
63 char *src, int len)
64 {
65 int rc = crypto_shash_tfm_digest(crypt_stat->hash_tfm, src, len, dst);
66
67 if (rc) {
68 printk(KERN_ERR
69 "%s: Error computing crypto hash; rc = [%d]\n",
70 __func__, rc);
71 goto out;
72 }
73 out:
74 return rc;
75 }
76
77 static int ecryptfs_crypto_api_algify_cipher_name(char **algified_name,
78 char *cipher_name,
79 char *chaining_modifier)
80 {
81 int cipher_name_len = strlen(cipher_name);
82 int chaining_modifier_len = strlen(chaining_modifier);
83 int algified_name_len;
84 int rc;
85
86 algified_name_len = (chaining_modifier_len + cipher_name_len + 3);
87 (*algified_name) = kmalloc(algified_name_len, GFP_KERNEL);
88 if (!(*algified_name)) {
89 rc = -ENOMEM;
90 goto out;
91 }
92 snprintf((*algified_name), algified_name_len, "%s(%s)",
93 chaining_modifier, cipher_name);
94 rc = 0;
95 out:
96 return rc;
97 }
98
99 /**
100 * ecryptfs_derive_iv
101 * @iv: destination for the derived iv vale
102 * @crypt_stat: Pointer to crypt_stat struct for the current inode
103 * @offset: Offset of the extent whose IV we are to derive
104 *
105 * Generate the initialization vector from the given root IV and page
106 * offset.
107 *
108 * Returns zero on success; non-zero on error.
109 */
110 int ecryptfs_derive_iv(char *iv, struct ecryptfs_crypt_stat *crypt_stat,
111 loff_t offset)
112 {
113 int rc = 0;
114 char dst[MD5_DIGEST_SIZE];
115 char src[ECRYPTFS_MAX_IV_BYTES + 16];
116
117 if (unlikely(ecryptfs_verbosity > 0)) {
118 ecryptfs_printk(KERN_DEBUG, "root iv:\n");
119 ecryptfs_dump_hex(crypt_stat->root_iv, crypt_stat->iv_bytes);
120 }
121 /* TODO: It is probably secure to just cast the least
122 * significant bits of the root IV into an unsigned long and
123 * add the offset to that rather than go through all this
124 * hashing business. -Halcrow */
125 memcpy(src, crypt_stat->root_iv, crypt_stat->iv_bytes);
126 memset((src + crypt_stat->iv_bytes), 0, 16);
127 snprintf((src + crypt_stat->iv_bytes), 16, "%lld", offset);
128 if (unlikely(ecryptfs_verbosity > 0)) {
129 ecryptfs_printk(KERN_DEBUG, "source:\n");
130 ecryptfs_dump_hex(src, (crypt_stat->iv_bytes + 16));
131 }
132 rc = ecryptfs_calculate_md5(dst, crypt_stat, src,
133 (crypt_stat->iv_bytes + 16));
134 if (rc) {
135 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
136 "MD5 while generating IV for a page\n");
137 goto out;
138 }
139 memcpy(iv, dst, crypt_stat->iv_bytes);
140 if (unlikely(ecryptfs_verbosity > 0)) {
141 ecryptfs_printk(KERN_DEBUG, "derived iv:\n");
142 ecryptfs_dump_hex(iv, crypt_stat->iv_bytes);
143 }
144 out:
145 return rc;
146 }
147
148 /**
149 * ecryptfs_init_crypt_stat
150 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
151 *
152 * Initialize the crypt_stat structure.
153 */
154 int ecryptfs_init_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
155 {
156 struct crypto_shash *tfm;
157 int rc;
158
159 tfm = crypto_alloc_shash(ECRYPTFS_DEFAULT_HASH, 0, 0);
160 if (IS_ERR(tfm)) {
161 rc = PTR_ERR(tfm);
162 ecryptfs_printk(KERN_ERR, "Error attempting to "
163 "allocate crypto context; rc = [%d]\n",
164 rc);
165 return rc;
166 }
167
168 memset((void *)crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
169 INIT_LIST_HEAD(&crypt_stat->keysig_list);
170 mutex_init(&crypt_stat->keysig_list_mutex);
171 mutex_init(&crypt_stat->cs_mutex);
172 mutex_init(&crypt_stat->cs_tfm_mutex);
173 crypt_stat->hash_tfm = tfm;
174 crypt_stat->flags |= ECRYPTFS_STRUCT_INITIALIZED;
175
176 return 0;
177 }
178
179 /**
180 * ecryptfs_destroy_crypt_stat
181 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
182 *
183 * Releases all memory associated with a crypt_stat struct.
184 */
185 void ecryptfs_destroy_crypt_stat(struct ecryptfs_crypt_stat *crypt_stat)
186 {
187 struct ecryptfs_key_sig *key_sig, *key_sig_tmp;
188
189 crypto_free_skcipher(crypt_stat->tfm);
190 crypto_free_shash(crypt_stat->hash_tfm);
191 list_for_each_entry_safe(key_sig, key_sig_tmp,
192 &crypt_stat->keysig_list, crypt_stat_list) {
193 list_del(&key_sig->crypt_stat_list);
194 kmem_cache_free(ecryptfs_key_sig_cache, key_sig);
195 }
196 memset(crypt_stat, 0, sizeof(struct ecryptfs_crypt_stat));
197 }
198
199 void ecryptfs_destroy_mount_crypt_stat(
200 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
201 {
202 struct ecryptfs_global_auth_tok *auth_tok, *auth_tok_tmp;
203
204 if (!(mount_crypt_stat->flags & ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED))
205 return;
206 mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
207 list_for_each_entry_safe(auth_tok, auth_tok_tmp,
208 &mount_crypt_stat->global_auth_tok_list,
209 mount_crypt_stat_list) {
210 list_del(&auth_tok->mount_crypt_stat_list);
211 if (!(auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID))
212 key_put(auth_tok->global_auth_tok_key);
213 kmem_cache_free(ecryptfs_global_auth_tok_cache, auth_tok);
214 }
215 mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
216 memset(mount_crypt_stat, 0, sizeof(struct ecryptfs_mount_crypt_stat));
217 }
218
219 /**
220 * virt_to_scatterlist
221 * @addr: Virtual address
222 * @size: Size of data; should be an even multiple of the block size
223 * @sg: Pointer to scatterlist array; set to NULL to obtain only
224 * the number of scatterlist structs required in array
225 * @sg_size: Max array size
226 *
227 * Fills in a scatterlist array with page references for a passed
228 * virtual address.
229 *
230 * Returns the number of scatterlist structs in array used
231 */
232 int virt_to_scatterlist(const void *addr, int size, struct scatterlist *sg,
233 int sg_size)
234 {
235 int i = 0;
236 struct page *pg;
237 int offset;
238 int remainder_of_page;
239
240 sg_init_table(sg, sg_size);
241
242 while (size > 0 && i < sg_size) {
243 pg = virt_to_page(addr);
244 offset = offset_in_page(addr);
245 sg_set_page(&sg[i], pg, 0, offset);
246 remainder_of_page = PAGE_SIZE - offset;
247 if (size >= remainder_of_page) {
248 sg[i].length = remainder_of_page;
249 addr += remainder_of_page;
250 size -= remainder_of_page;
251 } else {
252 sg[i].length = size;
253 addr += size;
254 size = 0;
255 }
256 i++;
257 }
258 if (size > 0)
259 return -ENOMEM;
260 return i;
261 }
262
263 /**
264 * crypt_scatterlist
265 * @crypt_stat: Pointer to the crypt_stat struct to initialize.
266 * @dst_sg: Destination of the data after performing the crypto operation
267 * @src_sg: Data to be encrypted or decrypted
268 * @size: Length of data
269 * @iv: IV to use
270 * @op: ENCRYPT or DECRYPT to indicate the desired operation
271 *
272 * Returns the number of bytes encrypted or decrypted; negative value on error
273 */
274 static int crypt_scatterlist(struct ecryptfs_crypt_stat *crypt_stat,
275 struct scatterlist *dst_sg,
276 struct scatterlist *src_sg, int size,
277 unsigned char *iv, int op)
278 {
279 struct skcipher_request *req = NULL;
280 DECLARE_CRYPTO_WAIT(ecr);
281 int rc = 0;
282
283 if (unlikely(ecryptfs_verbosity > 0)) {
284 ecryptfs_printk(KERN_DEBUG, "Key size [%zd]; key:\n",
285 crypt_stat->key_size);
286 ecryptfs_dump_hex(crypt_stat->key,
287 crypt_stat->key_size);
288 }
289
290 mutex_lock(&crypt_stat->cs_tfm_mutex);
291 req = skcipher_request_alloc(crypt_stat->tfm, GFP_NOFS);
292 if (!req) {
293 mutex_unlock(&crypt_stat->cs_tfm_mutex);
294 rc = -ENOMEM;
295 goto out;
296 }
297
298 skcipher_request_set_callback(req,
299 CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
300 crypto_req_done, &ecr);
301 /* Consider doing this once, when the file is opened */
302 if (!(crypt_stat->flags & ECRYPTFS_KEY_SET)) {
303 rc = crypto_skcipher_setkey(crypt_stat->tfm, crypt_stat->key,
304 crypt_stat->key_size);
305 if (rc) {
306 ecryptfs_printk(KERN_ERR,
307 "Error setting key; rc = [%d]\n",
308 rc);
309 mutex_unlock(&crypt_stat->cs_tfm_mutex);
310 rc = -EINVAL;
311 goto out;
312 }
313 crypt_stat->flags |= ECRYPTFS_KEY_SET;
314 }
315 mutex_unlock(&crypt_stat->cs_tfm_mutex);
316 skcipher_request_set_crypt(req, src_sg, dst_sg, size, iv);
317 rc = op == ENCRYPT ? crypto_skcipher_encrypt(req) :
318 crypto_skcipher_decrypt(req);
319 rc = crypto_wait_req(rc, &ecr);
320 out:
321 skcipher_request_free(req);
322 return rc;
323 }
324
325 /*
326 * lower_offset_for_page
327 *
328 * Convert an eCryptfs page index into a lower byte offset
329 */
330 static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
331 struct page *page)
332 {
333 return ecryptfs_lower_header_size(crypt_stat) +
334 ((loff_t)page->index << PAGE_SHIFT);
335 }
336
337 /**
338 * crypt_extent
339 * @crypt_stat: crypt_stat containing cryptographic context for the
340 * encryption operation
341 * @dst_page: The page to write the result into
342 * @src_page: The page to read from
343 * @extent_offset: Page extent offset for use in generating IV
344 * @op: ENCRYPT or DECRYPT to indicate the desired operation
345 *
346 * Encrypts or decrypts one extent of data.
347 *
348 * Return zero on success; non-zero otherwise
349 */
350 static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
351 struct page *dst_page,
352 struct page *src_page,
353 unsigned long extent_offset, int op)
354 {
355 pgoff_t page_index = op == ENCRYPT ? src_page->index : dst_page->index;
356 loff_t extent_base;
357 char extent_iv[ECRYPTFS_MAX_IV_BYTES];
358 struct scatterlist src_sg, dst_sg;
359 size_t extent_size = crypt_stat->extent_size;
360 int rc;
361
362 extent_base = (((loff_t)page_index) * (PAGE_SIZE / extent_size));
363 rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
364 (extent_base + extent_offset));
365 if (rc) {
366 ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
367 "extent [0x%.16llx]; rc = [%d]\n",
368 (unsigned long long)(extent_base + extent_offset), rc);
369 goto out;
370 }
371
372 sg_init_table(&src_sg, 1);
373 sg_init_table(&dst_sg, 1);
374
375 sg_set_page(&src_sg, src_page, extent_size,
376 extent_offset * extent_size);
377 sg_set_page(&dst_sg, dst_page, extent_size,
378 extent_offset * extent_size);
379
380 rc = crypt_scatterlist(crypt_stat, &dst_sg, &src_sg, extent_size,
381 extent_iv, op);
382 if (rc < 0) {
383 printk(KERN_ERR "%s: Error attempting to crypt page with "
384 "page_index = [%ld], extent_offset = [%ld]; "
385 "rc = [%d]\n", __func__, page_index, extent_offset, rc);
386 goto out;
387 }
388 rc = 0;
389 out:
390 return rc;
391 }
392
393 /**
394 * ecryptfs_encrypt_page
395 * @page: Page mapped from the eCryptfs inode for the file; contains
396 * decrypted content that needs to be encrypted (to a temporary
397 * page; not in place) and written out to the lower file
398 *
399 * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
400 * that eCryptfs pages may straddle the lower pages -- for instance,
401 * if the file was created on a machine with an 8K page size
402 * (resulting in an 8K header), and then the file is copied onto a
403 * host with a 32K page size, then when reading page 0 of the eCryptfs
404 * file, 24K of page 0 of the lower file will be read and decrypted,
405 * and then 8K of page 1 of the lower file will be read and decrypted.
406 *
407 * Returns zero on success; negative on error
408 */
409 int ecryptfs_encrypt_page(struct page *page)
410 {
411 struct inode *ecryptfs_inode;
412 struct ecryptfs_crypt_stat *crypt_stat;
413 char *enc_extent_virt;
414 struct page *enc_extent_page = NULL;
415 loff_t extent_offset;
416 loff_t lower_offset;
417 int rc = 0;
418
419 ecryptfs_inode = page->mapping->host;
420 crypt_stat =
421 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
422 BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
423 enc_extent_page = alloc_page(GFP_USER);
424 if (!enc_extent_page) {
425 rc = -ENOMEM;
426 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
427 "encrypted extent\n");
428 goto out;
429 }
430
431 for (extent_offset = 0;
432 extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
433 extent_offset++) {
434 rc = crypt_extent(crypt_stat, enc_extent_page, page,
435 extent_offset, ENCRYPT);
436 if (rc) {
437 printk(KERN_ERR "%s: Error encrypting extent; "
438 "rc = [%d]\n", __func__, rc);
439 goto out;
440 }
441 }
442
443 lower_offset = lower_offset_for_page(crypt_stat, page);
444 enc_extent_virt = kmap_local_page(enc_extent_page);
445 rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset,
446 PAGE_SIZE);
447 kunmap_local(enc_extent_virt);
448 if (rc < 0) {
449 ecryptfs_printk(KERN_ERR,
450 "Error attempting to write lower page; rc = [%d]\n",
451 rc);
452 goto out;
453 }
454 rc = 0;
455 out:
456 if (enc_extent_page) {
457 __free_page(enc_extent_page);
458 }
459 return rc;
460 }
461
462 /**
463 * ecryptfs_decrypt_page
464 * @page: Page mapped from the eCryptfs inode for the file; data read
465 * and decrypted from the lower file will be written into this
466 * page
467 *
468 * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
469 * that eCryptfs pages may straddle the lower pages -- for instance,
470 * if the file was created on a machine with an 8K page size
471 * (resulting in an 8K header), and then the file is copied onto a
472 * host with a 32K page size, then when reading page 0 of the eCryptfs
473 * file, 24K of page 0 of the lower file will be read and decrypted,
474 * and then 8K of page 1 of the lower file will be read and decrypted.
475 *
476 * Returns zero on success; negative on error
477 */
478 int ecryptfs_decrypt_page(struct page *page)
479 {
480 struct inode *ecryptfs_inode;
481 struct ecryptfs_crypt_stat *crypt_stat;
482 char *page_virt;
483 unsigned long extent_offset;
484 loff_t lower_offset;
485 int rc = 0;
486
487 ecryptfs_inode = page->mapping->host;
488 crypt_stat =
489 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
490 BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
491
492 lower_offset = lower_offset_for_page(crypt_stat, page);
493 page_virt = kmap_local_page(page);
494 rc = ecryptfs_read_lower(page_virt, lower_offset, PAGE_SIZE,
495 ecryptfs_inode);
496 kunmap_local(page_virt);
497 if (rc < 0) {
498 ecryptfs_printk(KERN_ERR,
499 "Error attempting to read lower page; rc = [%d]\n",
500 rc);
501 goto out;
502 }
503
504 for (extent_offset = 0;
505 extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
506 extent_offset++) {
507 rc = crypt_extent(crypt_stat, page, page,
508 extent_offset, DECRYPT);
509 if (rc) {
510 printk(KERN_ERR "%s: Error decrypting extent; "
511 "rc = [%d]\n", __func__, rc);
512 goto out;
513 }
514 }
515 out:
516 return rc;
517 }
518
519 #define ECRYPTFS_MAX_SCATTERLIST_LEN 4
520
521 /**
522 * ecryptfs_init_crypt_ctx
523 * @crypt_stat: Uninitialized crypt stats structure
524 *
525 * Initialize the crypto context.
526 *
527 * TODO: Performance: Keep a cache of initialized cipher contexts;
528 * only init if needed
529 */
530 int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
531 {
532 char *full_alg_name;
533 int rc = -EINVAL;
534
535 ecryptfs_printk(KERN_DEBUG,
536 "Initializing cipher [%s]; strlen = [%d]; "
537 "key_size_bits = [%zd]\n",
538 crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
539 crypt_stat->key_size << 3);
540 mutex_lock(&crypt_stat->cs_tfm_mutex);
541 if (crypt_stat->tfm) {
542 rc = 0;
543 goto out_unlock;
544 }
545 rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
546 crypt_stat->cipher, "cbc");
547 if (rc)
548 goto out_unlock;
549 crypt_stat->tfm = crypto_alloc_skcipher(full_alg_name, 0, 0);
550 if (IS_ERR(crypt_stat->tfm)) {
551 rc = PTR_ERR(crypt_stat->tfm);
552 crypt_stat->tfm = NULL;
553 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
554 "Error initializing cipher [%s]\n",
555 full_alg_name);
556 goto out_free;
557 }
558 crypto_skcipher_set_flags(crypt_stat->tfm,
559 CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
560 rc = 0;
561 out_free:
562 kfree(full_alg_name);
563 out_unlock:
564 mutex_unlock(&crypt_stat->cs_tfm_mutex);
565 return rc;
566 }
567
568 static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
569 {
570 int extent_size_tmp;
571
572 crypt_stat->extent_mask = 0xFFFFFFFF;
573 crypt_stat->extent_shift = 0;
574 if (crypt_stat->extent_size == 0)
575 return;
576 extent_size_tmp = crypt_stat->extent_size;
577 while ((extent_size_tmp & 0x01) == 0) {
578 extent_size_tmp >>= 1;
579 crypt_stat->extent_mask <<= 1;
580 crypt_stat->extent_shift++;
581 }
582 }
583
584 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
585 {
586 /* Default values; may be overwritten as we are parsing the
587 * packets. */
588 crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
589 set_extent_mask_and_shift(crypt_stat);
590 crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
591 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
592 crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
593 else {
594 if (PAGE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
595 crypt_stat->metadata_size =
596 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
597 else
598 crypt_stat->metadata_size = PAGE_SIZE;
599 }
600 }
601
602 /*
603 * ecryptfs_compute_root_iv
604 *
605 * On error, sets the root IV to all 0's.
606 */
607 int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
608 {
609 int rc = 0;
610 char dst[MD5_DIGEST_SIZE];
611
612 BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
613 BUG_ON(crypt_stat->iv_bytes <= 0);
614 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
615 rc = -EINVAL;
616 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
617 "cannot generate root IV\n");
618 goto out;
619 }
620 rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
621 crypt_stat->key_size);
622 if (rc) {
623 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
624 "MD5 while generating root IV\n");
625 goto out;
626 }
627 memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
628 out:
629 if (rc) {
630 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
631 crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
632 }
633 return rc;
634 }
635
636 static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
637 {
638 get_random_bytes(crypt_stat->key, crypt_stat->key_size);
639 crypt_stat->flags |= ECRYPTFS_KEY_VALID;
640 ecryptfs_compute_root_iv(crypt_stat);
641 if (unlikely(ecryptfs_verbosity > 0)) {
642 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
643 ecryptfs_dump_hex(crypt_stat->key,
644 crypt_stat->key_size);
645 }
646 }
647
648 /**
649 * ecryptfs_copy_mount_wide_flags_to_inode_flags
650 * @crypt_stat: The inode's cryptographic context
651 * @mount_crypt_stat: The mount point's cryptographic context
652 *
653 * This function propagates the mount-wide flags to individual inode
654 * flags.
655 */
656 static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
657 struct ecryptfs_crypt_stat *crypt_stat,
658 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
659 {
660 if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
661 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
662 if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
663 crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
664 if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
665 crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
666 if (mount_crypt_stat->flags
667 & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
668 crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
669 else if (mount_crypt_stat->flags
670 & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
671 crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
672 }
673 }
674
675 static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
676 struct ecryptfs_crypt_stat *crypt_stat,
677 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
678 {
679 struct ecryptfs_global_auth_tok *global_auth_tok;
680 int rc = 0;
681
682 mutex_lock(&crypt_stat->keysig_list_mutex);
683 mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
684
685 list_for_each_entry(global_auth_tok,
686 &mount_crypt_stat->global_auth_tok_list,
687 mount_crypt_stat_list) {
688 if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
689 continue;
690 rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
691 if (rc) {
692 printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
693 goto out;
694 }
695 }
696
697 out:
698 mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
699 mutex_unlock(&crypt_stat->keysig_list_mutex);
700 return rc;
701 }
702
703 /**
704 * ecryptfs_set_default_crypt_stat_vals
705 * @crypt_stat: The inode's cryptographic context
706 * @mount_crypt_stat: The mount point's cryptographic context
707 *
708 * Default values in the event that policy does not override them.
709 */
710 static void ecryptfs_set_default_crypt_stat_vals(
711 struct ecryptfs_crypt_stat *crypt_stat,
712 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
713 {
714 ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
715 mount_crypt_stat);
716 ecryptfs_set_default_sizes(crypt_stat);
717 strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
718 crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
719 crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
720 crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
721 crypt_stat->mount_crypt_stat = mount_crypt_stat;
722 }
723
724 /**
725 * ecryptfs_new_file_context
726 * @ecryptfs_inode: The eCryptfs inode
727 *
728 * If the crypto context for the file has not yet been established,
729 * this is where we do that. Establishing a new crypto context
730 * involves the following decisions:
731 * - What cipher to use?
732 * - What set of authentication tokens to use?
733 * Here we just worry about getting enough information into the
734 * authentication tokens so that we know that they are available.
735 * We associate the available authentication tokens with the new file
736 * via the set of signatures in the crypt_stat struct. Later, when
737 * the headers are actually written out, we may again defer to
738 * userspace to perform the encryption of the session key; for the
739 * foreseeable future, this will be the case with public key packets.
740 *
741 * Returns zero on success; non-zero otherwise
742 */
743 int ecryptfs_new_file_context(struct inode *ecryptfs_inode)
744 {
745 struct ecryptfs_crypt_stat *crypt_stat =
746 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
747 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
748 &ecryptfs_superblock_to_private(
749 ecryptfs_inode->i_sb)->mount_crypt_stat;
750 int cipher_name_len;
751 int rc = 0;
752
753 ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
754 crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
755 ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
756 mount_crypt_stat);
757 rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
758 mount_crypt_stat);
759 if (rc) {
760 printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
761 "to the inode key sigs; rc = [%d]\n", rc);
762 goto out;
763 }
764 cipher_name_len =
765 strlen(mount_crypt_stat->global_default_cipher_name);
766 memcpy(crypt_stat->cipher,
767 mount_crypt_stat->global_default_cipher_name,
768 cipher_name_len);
769 crypt_stat->cipher[cipher_name_len] = '\0';
770 crypt_stat->key_size =
771 mount_crypt_stat->global_default_cipher_key_size;
772 ecryptfs_generate_new_key(crypt_stat);
773 rc = ecryptfs_init_crypt_ctx(crypt_stat);
774 if (rc)
775 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
776 "context for cipher [%s]: rc = [%d]\n",
777 crypt_stat->cipher, rc);
778 out:
779 return rc;
780 }
781
782 /**
783 * ecryptfs_validate_marker - check for the ecryptfs marker
784 * @data: The data block in which to check
785 *
786 * Returns zero if marker found; -EINVAL if not found
787 */
788 static int ecryptfs_validate_marker(char *data)
789 {
790 u32 m_1, m_2;
791
792 m_1 = get_unaligned_be32(data);
793 m_2 = get_unaligned_be32(data + 4);
794 if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
795 return 0;
796 ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
797 "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
798 MAGIC_ECRYPTFS_MARKER);
799 ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
800 "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
801 return -EINVAL;
802 }
803
804 struct ecryptfs_flag_map_elem {
805 u32 file_flag;
806 u32 local_flag;
807 };
808
809 /* Add support for additional flags by adding elements here. */
810 static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
811 {0x00000001, ECRYPTFS_ENABLE_HMAC},
812 {0x00000002, ECRYPTFS_ENCRYPTED},
813 {0x00000004, ECRYPTFS_METADATA_IN_XATTR},
814 {0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
815 };
816
817 /**
818 * ecryptfs_process_flags
819 * @crypt_stat: The cryptographic context
820 * @page_virt: Source data to be parsed
821 * @bytes_read: Updated with the number of bytes read
822 */
823 static void ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
824 char *page_virt, int *bytes_read)
825 {
826 int i;
827 u32 flags;
828
829 flags = get_unaligned_be32(page_virt);
830 for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++)
831 if (flags & ecryptfs_flag_map[i].file_flag) {
832 crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
833 } else
834 crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
835 /* Version is in top 8 bits of the 32-bit flag vector */
836 crypt_stat->file_version = ((flags >> 24) & 0xFF);
837 (*bytes_read) = 4;
838 }
839
840 /**
841 * write_ecryptfs_marker
842 * @page_virt: The pointer to in a page to begin writing the marker
843 * @written: Number of bytes written
844 *
845 * Marker = 0x3c81b7f5
846 */
847 static void write_ecryptfs_marker(char *page_virt, size_t *written)
848 {
849 u32 m_1, m_2;
850
851 get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
852 m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
853 put_unaligned_be32(m_1, page_virt);
854 page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
855 put_unaligned_be32(m_2, page_virt);
856 (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
857 }
858
859 void ecryptfs_write_crypt_stat_flags(char *page_virt,
860 struct ecryptfs_crypt_stat *crypt_stat,
861 size_t *written)
862 {
863 u32 flags = 0;
864 int i;
865
866 for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++)
867 if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
868 flags |= ecryptfs_flag_map[i].file_flag;
869 /* Version is in top 8 bits of the 32-bit flag vector */
870 flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
871 put_unaligned_be32(flags, page_virt);
872 (*written) = 4;
873 }
874
875 struct ecryptfs_cipher_code_str_map_elem {
876 char cipher_str[16];
877 u8 cipher_code;
878 };
879
880 /* Add support for additional ciphers by adding elements here. The
881 * cipher_code is whatever OpenPGP applications use to identify the
882 * ciphers. List in order of probability. */
883 static struct ecryptfs_cipher_code_str_map_elem
884 ecryptfs_cipher_code_str_map[] = {
885 {"aes",RFC2440_CIPHER_AES_128 },
886 {"blowfish", RFC2440_CIPHER_BLOWFISH},
887 {"des3_ede", RFC2440_CIPHER_DES3_EDE},
888 {"cast5", RFC2440_CIPHER_CAST_5},
889 {"twofish", RFC2440_CIPHER_TWOFISH},
890 {"cast6", RFC2440_CIPHER_CAST_6},
891 {"aes", RFC2440_CIPHER_AES_192},
892 {"aes", RFC2440_CIPHER_AES_256}
893 };
894
895 /**
896 * ecryptfs_code_for_cipher_string
897 * @cipher_name: The string alias for the cipher
898 * @key_bytes: Length of key in bytes; used for AES code selection
899 *
900 * Returns zero on no match, or the cipher code on match
901 */
902 u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
903 {
904 int i;
905 u8 code = 0;
906 struct ecryptfs_cipher_code_str_map_elem *map =
907 ecryptfs_cipher_code_str_map;
908
909 if (strcmp(cipher_name, "aes") == 0) {
910 switch (key_bytes) {
911 case 16:
912 code = RFC2440_CIPHER_AES_128;
913 break;
914 case 24:
915 code = RFC2440_CIPHER_AES_192;
916 break;
917 case 32:
918 code = RFC2440_CIPHER_AES_256;
919 }
920 } else {
921 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
922 if (strcmp(cipher_name, map[i].cipher_str) == 0) {
923 code = map[i].cipher_code;
924 break;
925 }
926 }
927 return code;
928 }
929
930 /**
931 * ecryptfs_cipher_code_to_string
932 * @str: Destination to write out the cipher name
933 * @cipher_code: The code to convert to cipher name string
934 *
935 * Returns zero on success
936 */
937 int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
938 {
939 int rc = 0;
940 int i;
941
942 str[0] = '\0';
943 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
944 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
945 strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
946 if (str[0] == '\0') {
947 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
948 "[%d]\n", cipher_code);
949 rc = -EINVAL;
950 }
951 return rc;
952 }
953
954 int ecryptfs_read_and_validate_header_region(struct inode *inode)
955 {
956 u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
957 u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
958 int rc;
959
960 rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
961 inode);
962 if (rc < 0)
963 return rc;
964 else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
965 return -EINVAL;
966 rc = ecryptfs_validate_marker(marker);
967 if (!rc)
968 ecryptfs_i_size_init(file_size, inode);
969 return rc;
970 }
971
972 void
973 ecryptfs_write_header_metadata(char *virt,
974 struct ecryptfs_crypt_stat *crypt_stat,
975 size_t *written)
976 {
977 u32 header_extent_size;
978 u16 num_header_extents_at_front;
979
980 header_extent_size = (u32)crypt_stat->extent_size;
981 num_header_extents_at_front =
982 (u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
983 put_unaligned_be32(header_extent_size, virt);
984 virt += 4;
985 put_unaligned_be16(num_header_extents_at_front, virt);
986 (*written) = 6;
987 }
988
989 struct kmem_cache *ecryptfs_header_cache;
990
991 /**
992 * ecryptfs_write_headers_virt
993 * @page_virt: The virtual address to write the headers to
994 * @max: The size of memory allocated at page_virt
995 * @size: Set to the number of bytes written by this function
996 * @crypt_stat: The cryptographic context
997 * @ecryptfs_dentry: The eCryptfs dentry
998 *
999 * Format version: 1
1000 *
1001 * Header Extent:
1002 * Octets 0-7: Unencrypted file size (big-endian)
1003 * Octets 8-15: eCryptfs special marker
1004 * Octets 16-19: Flags
1005 * Octet 16: File format version number (between 0 and 255)
1006 * Octets 17-18: Reserved
1007 * Octet 19: Bit 1 (lsb): Reserved
1008 * Bit 2: Encrypted?
1009 * Bits 3-8: Reserved
1010 * Octets 20-23: Header extent size (big-endian)
1011 * Octets 24-25: Number of header extents at front of file
1012 * (big-endian)
1013 * Octet 26: Begin RFC 2440 authentication token packet set
1014 * Data Extent 0:
1015 * Lower data (CBC encrypted)
1016 * Data Extent 1:
1017 * Lower data (CBC encrypted)
1018 * ...
1019 *
1020 * Returns zero on success
1021 */
1022 static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
1023 size_t *size,
1024 struct ecryptfs_crypt_stat *crypt_stat,
1025 struct dentry *ecryptfs_dentry)
1026 {
1027 int rc;
1028 size_t written;
1029 size_t offset;
1030
1031 offset = ECRYPTFS_FILE_SIZE_BYTES;
1032 write_ecryptfs_marker((page_virt + offset), &written);
1033 offset += written;
1034 ecryptfs_write_crypt_stat_flags((page_virt + offset), crypt_stat,
1035 &written);
1036 offset += written;
1037 ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1038 &written);
1039 offset += written;
1040 rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1041 ecryptfs_dentry, &written,
1042 max - offset);
1043 if (rc)
1044 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1045 "set; rc = [%d]\n", rc);
1046 if (size) {
1047 offset += written;
1048 *size = offset;
1049 }
1050 return rc;
1051 }
1052
1053 static int
1054 ecryptfs_write_metadata_to_contents(struct inode *ecryptfs_inode,
1055 char *virt, size_t virt_len)
1056 {
1057 int rc;
1058
1059 rc = ecryptfs_write_lower(ecryptfs_inode, virt,
1060 0, virt_len);
1061 if (rc < 0)
1062 printk(KERN_ERR "%s: Error attempting to write header "
1063 "information to lower file; rc = [%d]\n", __func__, rc);
1064 else
1065 rc = 0;
1066 return rc;
1067 }
1068
1069 static int
1070 ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1071 struct inode *ecryptfs_inode,
1072 char *page_virt, size_t size)
1073 {
1074 int rc;
1075 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
1076 struct inode *lower_inode = d_inode(lower_dentry);
1077
1078 if (!(lower_inode->i_opflags & IOP_XATTR)) {
1079 rc = -EOPNOTSUPP;
1080 goto out;
1081 }
1082
1083 inode_lock(lower_inode);
1084 rc = __vfs_setxattr(&nop_mnt_idmap, lower_dentry, lower_inode,
1085 ECRYPTFS_XATTR_NAME, page_virt, size, 0);
1086 if (!rc && ecryptfs_inode)
1087 fsstack_copy_attr_all(ecryptfs_inode, lower_inode);
1088 inode_unlock(lower_inode);
1089 out:
1090 return rc;
1091 }
1092
1093 static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
1094 unsigned int order)
1095 {
1096 struct page *page;
1097
1098 page = alloc_pages(gfp_mask | __GFP_ZERO, order);
1099 if (page)
1100 return (unsigned long) page_address(page);
1101 return 0;
1102 }
1103
1104 /**
1105 * ecryptfs_write_metadata
1106 * @ecryptfs_dentry: The eCryptfs dentry, which should be negative
1107 * @ecryptfs_inode: The newly created eCryptfs inode
1108 *
1109 * Write the file headers out. This will likely involve a userspace
1110 * callout, in which the session key is encrypted with one or more
1111 * public keys and/or the passphrase necessary to do the encryption is
1112 * retrieved via a prompt. Exactly what happens at this point should
1113 * be policy-dependent.
1114 *
1115 * Returns zero on success; non-zero on error
1116 */
1117 int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1118 struct inode *ecryptfs_inode)
1119 {
1120 struct ecryptfs_crypt_stat *crypt_stat =
1121 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1122 unsigned int order;
1123 char *virt;
1124 size_t virt_len;
1125 size_t size = 0;
1126 int rc = 0;
1127
1128 if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1129 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1130 printk(KERN_ERR "Key is invalid; bailing out\n");
1131 rc = -EINVAL;
1132 goto out;
1133 }
1134 } else {
1135 printk(KERN_WARNING "%s: Encrypted flag not set\n",
1136 __func__);
1137 rc = -EINVAL;
1138 goto out;
1139 }
1140 virt_len = crypt_stat->metadata_size;
1141 order = get_order(virt_len);
1142 /* Released in this function */
1143 virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
1144 if (!virt) {
1145 printk(KERN_ERR "%s: Out of memory\n", __func__);
1146 rc = -ENOMEM;
1147 goto out;
1148 }
1149 /* Zeroed page ensures the in-header unencrypted i_size is set to 0 */
1150 rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
1151 ecryptfs_dentry);
1152 if (unlikely(rc)) {
1153 printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
1154 __func__, rc);
1155 goto out_free;
1156 }
1157 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1158 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, ecryptfs_inode,
1159 virt, size);
1160 else
1161 rc = ecryptfs_write_metadata_to_contents(ecryptfs_inode, virt,
1162 virt_len);
1163 if (rc) {
1164 printk(KERN_ERR "%s: Error writing metadata out to lower file; "
1165 "rc = [%d]\n", __func__, rc);
1166 goto out_free;
1167 }
1168 out_free:
1169 free_pages((unsigned long)virt, order);
1170 out:
1171 return rc;
1172 }
1173
1174 #define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1175 #define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1176 static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1177 char *virt, int *bytes_read,
1178 int validate_header_size)
1179 {
1180 int rc = 0;
1181 u32 header_extent_size;
1182 u16 num_header_extents_at_front;
1183
1184 header_extent_size = get_unaligned_be32(virt);
1185 virt += sizeof(__be32);
1186 num_header_extents_at_front = get_unaligned_be16(virt);
1187 crypt_stat->metadata_size = (((size_t)num_header_extents_at_front
1188 * (size_t)header_extent_size));
1189 (*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1190 if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1191 && (crypt_stat->metadata_size
1192 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1193 rc = -EINVAL;
1194 printk(KERN_WARNING "Invalid header size: [%zd]\n",
1195 crypt_stat->metadata_size);
1196 }
1197 return rc;
1198 }
1199
1200 /**
1201 * set_default_header_data
1202 * @crypt_stat: The cryptographic context
1203 *
1204 * For version 0 file format; this function is only for backwards
1205 * compatibility for files created with the prior versions of
1206 * eCryptfs.
1207 */
1208 static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1209 {
1210 crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1211 }
1212
1213 void ecryptfs_i_size_init(const char *page_virt, struct inode *inode)
1214 {
1215 struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
1216 struct ecryptfs_crypt_stat *crypt_stat;
1217 u64 file_size;
1218
1219 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
1220 mount_crypt_stat =
1221 &ecryptfs_superblock_to_private(inode->i_sb)->mount_crypt_stat;
1222 if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
1223 file_size = i_size_read(ecryptfs_inode_to_lower(inode));
1224 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1225 file_size += crypt_stat->metadata_size;
1226 } else
1227 file_size = get_unaligned_be64(page_virt);
1228 i_size_write(inode, (loff_t)file_size);
1229 crypt_stat->flags |= ECRYPTFS_I_SIZE_INITIALIZED;
1230 }
1231
1232 /**
1233 * ecryptfs_read_headers_virt
1234 * @page_virt: The virtual address into which to read the headers
1235 * @crypt_stat: The cryptographic context
1236 * @ecryptfs_dentry: The eCryptfs dentry
1237 * @validate_header_size: Whether to validate the header size while reading
1238 *
1239 * Read/parse the header data. The header format is detailed in the
1240 * comment block for the ecryptfs_write_headers_virt() function.
1241 *
1242 * Returns zero on success
1243 */
1244 static int ecryptfs_read_headers_virt(char *page_virt,
1245 struct ecryptfs_crypt_stat *crypt_stat,
1246 struct dentry *ecryptfs_dentry,
1247 int validate_header_size)
1248 {
1249 int rc = 0;
1250 int offset;
1251 int bytes_read;
1252
1253 ecryptfs_set_default_sizes(crypt_stat);
1254 crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1255 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1256 offset = ECRYPTFS_FILE_SIZE_BYTES;
1257 rc = ecryptfs_validate_marker(page_virt + offset);
1258 if (rc)
1259 goto out;
1260 if (!(crypt_stat->flags & ECRYPTFS_I_SIZE_INITIALIZED))
1261 ecryptfs_i_size_init(page_virt, d_inode(ecryptfs_dentry));
1262 offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1263 ecryptfs_process_flags(crypt_stat, (page_virt + offset), &bytes_read);
1264 if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1265 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1266 "file version [%d] is supported by this "
1267 "version of eCryptfs\n",
1268 crypt_stat->file_version,
1269 ECRYPTFS_SUPPORTED_FILE_VERSION);
1270 rc = -EINVAL;
1271 goto out;
1272 }
1273 offset += bytes_read;
1274 if (crypt_stat->file_version >= 1) {
1275 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1276 &bytes_read, validate_header_size);
1277 if (rc) {
1278 ecryptfs_printk(KERN_WARNING, "Error reading header "
1279 "metadata; rc = [%d]\n", rc);
1280 }
1281 offset += bytes_read;
1282 } else
1283 set_default_header_data(crypt_stat);
1284 rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1285 ecryptfs_dentry);
1286 out:
1287 return rc;
1288 }
1289
1290 /**
1291 * ecryptfs_read_xattr_region
1292 * @page_virt: The vitual address into which to read the xattr data
1293 * @ecryptfs_inode: The eCryptfs inode
1294 *
1295 * Attempts to read the crypto metadata from the extended attribute
1296 * region of the lower file.
1297 *
1298 * Returns zero on success; non-zero on error
1299 */
1300 int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1301 {
1302 struct dentry *lower_dentry =
1303 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_path.dentry;
1304 ssize_t size;
1305 int rc = 0;
1306
1307 size = ecryptfs_getxattr_lower(lower_dentry,
1308 ecryptfs_inode_to_lower(ecryptfs_inode),
1309 ECRYPTFS_XATTR_NAME,
1310 page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1311 if (size < 0) {
1312 if (unlikely(ecryptfs_verbosity > 0))
1313 printk(KERN_INFO "Error attempting to read the [%s] "
1314 "xattr from the lower file; return value = "
1315 "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1316 rc = -EINVAL;
1317 goto out;
1318 }
1319 out:
1320 return rc;
1321 }
1322
1323 int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
1324 struct inode *inode)
1325 {
1326 u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1327 u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1328 int rc;
1329
1330 rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
1331 ecryptfs_inode_to_lower(inode),
1332 ECRYPTFS_XATTR_NAME, file_size,
1333 ECRYPTFS_SIZE_AND_MARKER_BYTES);
1334 if (rc < 0)
1335 return rc;
1336 else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1337 return -EINVAL;
1338 rc = ecryptfs_validate_marker(marker);
1339 if (!rc)
1340 ecryptfs_i_size_init(file_size, inode);
1341 return rc;
1342 }
1343
1344 /*
1345 * ecryptfs_read_metadata
1346 *
1347 * Common entry point for reading file metadata. From here, we could
1348 * retrieve the header information from the header region of the file,
1349 * the xattr region of the file, or some other repository that is
1350 * stored separately from the file itself. The current implementation
1351 * supports retrieving the metadata information from the file contents
1352 * and from the xattr region.
1353 *
1354 * Returns zero if valid headers found and parsed; non-zero otherwise
1355 */
1356 int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1357 {
1358 int rc;
1359 char *page_virt;
1360 struct inode *ecryptfs_inode = d_inode(ecryptfs_dentry);
1361 struct ecryptfs_crypt_stat *crypt_stat =
1362 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1363 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1364 &ecryptfs_superblock_to_private(
1365 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1366
1367 ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1368 mount_crypt_stat);
1369 /* Read the first page from the underlying file */
1370 page_virt = kmem_cache_alloc(ecryptfs_header_cache, GFP_USER);
1371 if (!page_virt) {
1372 rc = -ENOMEM;
1373 goto out;
1374 }
1375 rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
1376 ecryptfs_inode);
1377 if (rc >= 0)
1378 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1379 ecryptfs_dentry,
1380 ECRYPTFS_VALIDATE_HEADER_SIZE);
1381 if (rc) {
1382 /* metadata is not in the file header, so try xattrs */
1383 memset(page_virt, 0, PAGE_SIZE);
1384 rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1385 if (rc) {
1386 printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1387 "file header region or xattr region, inode %lu\n",
1388 ecryptfs_inode->i_ino);
1389 rc = -EINVAL;
1390 goto out;
1391 }
1392 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1393 ecryptfs_dentry,
1394 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1395 if (rc) {
1396 printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1397 "file xattr region either, inode %lu\n",
1398 ecryptfs_inode->i_ino);
1399 rc = -EINVAL;
1400 }
1401 if (crypt_stat->mount_crypt_stat->flags
1402 & ECRYPTFS_XATTR_METADATA_ENABLED) {
1403 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1404 } else {
1405 printk(KERN_WARNING "Attempt to access file with "
1406 "crypto metadata only in the extended attribute "
1407 "region, but eCryptfs was mounted without "
1408 "xattr support enabled. eCryptfs will not treat "
1409 "this like an encrypted file, inode %lu\n",
1410 ecryptfs_inode->i_ino);
1411 rc = -EINVAL;
1412 }
1413 }
1414 out:
1415 if (page_virt) {
1416 memset(page_virt, 0, PAGE_SIZE);
1417 kmem_cache_free(ecryptfs_header_cache, page_virt);
1418 }
1419 return rc;
1420 }
1421
1422 /*
1423 * ecryptfs_encrypt_filename - encrypt filename
1424 *
1425 * CBC-encrypts the filename. We do not want to encrypt the same
1426 * filename with the same key and IV, which may happen with hard
1427 * links, so we prepend random bits to each filename.
1428 *
1429 * Returns zero on success; non-zero otherwise
1430 */
1431 static int
1432 ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1433 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1434 {
1435 int rc = 0;
1436
1437 filename->encrypted_filename = NULL;
1438 filename->encrypted_filename_size = 0;
1439 if (mount_crypt_stat && (mount_crypt_stat->flags
1440 & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
1441 size_t packet_size;
1442 size_t remaining_bytes;
1443
1444 rc = ecryptfs_write_tag_70_packet(
1445 NULL, NULL,
1446 &filename->encrypted_filename_size,
1447 mount_crypt_stat, NULL,
1448 filename->filename_size);
1449 if (rc) {
1450 printk(KERN_ERR "%s: Error attempting to get packet "
1451 "size for tag 72; rc = [%d]\n", __func__,
1452 rc);
1453 filename->encrypted_filename_size = 0;
1454 goto out;
1455 }
1456 filename->encrypted_filename =
1457 kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1458 if (!filename->encrypted_filename) {
1459 rc = -ENOMEM;
1460 goto out;
1461 }
1462 remaining_bytes = filename->encrypted_filename_size;
1463 rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
1464 &remaining_bytes,
1465 &packet_size,
1466 mount_crypt_stat,
1467 filename->filename,
1468 filename->filename_size);
1469 if (rc) {
1470 printk(KERN_ERR "%s: Error attempting to generate "
1471 "tag 70 packet; rc = [%d]\n", __func__,
1472 rc);
1473 kfree(filename->encrypted_filename);
1474 filename->encrypted_filename = NULL;
1475 filename->encrypted_filename_size = 0;
1476 goto out;
1477 }
1478 filename->encrypted_filename_size = packet_size;
1479 } else {
1480 printk(KERN_ERR "%s: No support for requested filename "
1481 "encryption method in this release\n", __func__);
1482 rc = -EOPNOTSUPP;
1483 goto out;
1484 }
1485 out:
1486 return rc;
1487 }
1488
1489 static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1490 const char *name, size_t name_size)
1491 {
1492 int rc = 0;
1493
1494 (*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1495 if (!(*copied_name)) {
1496 rc = -ENOMEM;
1497 goto out;
1498 }
1499 memcpy((void *)(*copied_name), (void *)name, name_size);
1500 (*copied_name)[(name_size)] = '\0'; /* Only for convenience
1501 * in printing out the
1502 * string in debug
1503 * messages */
1504 (*copied_name_size) = name_size;
1505 out:
1506 return rc;
1507 }
1508
1509 /**
1510 * ecryptfs_process_key_cipher - Perform key cipher initialization.
1511 * @key_tfm: Crypto context for key material, set by this function
1512 * @cipher_name: Name of the cipher
1513 * @key_size: Size of the key in bytes
1514 *
1515 * Returns zero on success. Any crypto_tfm structs allocated here
1516 * should be released by other functions, such as on a superblock put
1517 * event, regardless of whether this function succeeds for fails.
1518 */
1519 static int
1520 ecryptfs_process_key_cipher(struct crypto_skcipher **key_tfm,
1521 char *cipher_name, size_t *key_size)
1522 {
1523 char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1524 char *full_alg_name = NULL;
1525 int rc;
1526
1527 *key_tfm = NULL;
1528 if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1529 rc = -EINVAL;
1530 printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1531 "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1532 goto out;
1533 }
1534 rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1535 "ecb");
1536 if (rc)
1537 goto out;
1538 *key_tfm = crypto_alloc_skcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1539 if (IS_ERR(*key_tfm)) {
1540 rc = PTR_ERR(*key_tfm);
1541 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1542 "[%s]; rc = [%d]\n", full_alg_name, rc);
1543 goto out;
1544 }
1545 crypto_skcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
1546 if (*key_size == 0)
1547 *key_size = crypto_skcipher_max_keysize(*key_tfm);
1548 get_random_bytes(dummy_key, *key_size);
1549 rc = crypto_skcipher_setkey(*key_tfm, dummy_key, *key_size);
1550 if (rc) {
1551 printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1552 "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
1553 rc);
1554 rc = -EINVAL;
1555 goto out;
1556 }
1557 out:
1558 kfree(full_alg_name);
1559 return rc;
1560 }
1561
1562 struct kmem_cache *ecryptfs_key_tfm_cache;
1563 static struct list_head key_tfm_list;
1564 DEFINE_MUTEX(key_tfm_list_mutex);
1565
1566 int __init ecryptfs_init_crypto(void)
1567 {
1568 INIT_LIST_HEAD(&key_tfm_list);
1569 return 0;
1570 }
1571
1572 /**
1573 * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
1574 *
1575 * Called only at module unload time
1576 */
1577 int ecryptfs_destroy_crypto(void)
1578 {
1579 struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1580
1581 mutex_lock(&key_tfm_list_mutex);
1582 list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1583 key_tfm_list) {
1584 list_del(&key_tfm->key_tfm_list);
1585 crypto_free_skcipher(key_tfm->key_tfm);
1586 kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1587 }
1588 mutex_unlock(&key_tfm_list_mutex);
1589 return 0;
1590 }
1591
1592 int
1593 ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1594 size_t key_size)
1595 {
1596 struct ecryptfs_key_tfm *tmp_tfm;
1597 int rc = 0;
1598
1599 BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1600
1601 tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1602 if (key_tfm)
1603 (*key_tfm) = tmp_tfm;
1604 if (!tmp_tfm) {
1605 rc = -ENOMEM;
1606 goto out;
1607 }
1608 mutex_init(&tmp_tfm->key_tfm_mutex);
1609 strscpy(tmp_tfm->cipher_name, cipher_name);
1610 tmp_tfm->key_size = key_size;
1611 rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1612 tmp_tfm->cipher_name,
1613 &tmp_tfm->key_size);
1614 if (rc) {
1615 printk(KERN_ERR "Error attempting to initialize key TFM "
1616 "cipher with name = [%s]; rc = [%d]\n",
1617 tmp_tfm->cipher_name, rc);
1618 kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1619 if (key_tfm)
1620 (*key_tfm) = NULL;
1621 goto out;
1622 }
1623 list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1624 out:
1625 return rc;
1626 }
1627
1628 /**
1629 * ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
1630 * @cipher_name: the name of the cipher to search for
1631 * @key_tfm: set to corresponding tfm if found
1632 *
1633 * Searches for cached key_tfm matching @cipher_name
1634 * Must be called with &key_tfm_list_mutex held
1635 * Returns 1 if found, with @key_tfm set
1636 * Returns 0 if not found, with @key_tfm set to NULL
1637 */
1638 int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
1639 {
1640 struct ecryptfs_key_tfm *tmp_key_tfm;
1641
1642 BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1643
1644 list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
1645 if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
1646 if (key_tfm)
1647 (*key_tfm) = tmp_key_tfm;
1648 return 1;
1649 }
1650 }
1651 if (key_tfm)
1652 (*key_tfm) = NULL;
1653 return 0;
1654 }
1655
1656 /**
1657 * ecryptfs_get_tfm_and_mutex_for_cipher_name
1658 *
1659 * @tfm: set to cached tfm found, or new tfm created
1660 * @tfm_mutex: set to mutex for cached tfm found, or new tfm created
1661 * @cipher_name: the name of the cipher to search for and/or add
1662 *
1663 * Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
1664 * Searches for cached item first, and creates new if not found.
1665 * Returns 0 on success, non-zero if adding new cipher failed
1666 */
1667 int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_skcipher **tfm,
1668 struct mutex **tfm_mutex,
1669 char *cipher_name)
1670 {
1671 struct ecryptfs_key_tfm *key_tfm;
1672 int rc = 0;
1673
1674 (*tfm) = NULL;
1675 (*tfm_mutex) = NULL;
1676
1677 mutex_lock(&key_tfm_list_mutex);
1678 if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) {
1679 rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
1680 if (rc) {
1681 printk(KERN_ERR "Error adding new key_tfm to list; "
1682 "rc = [%d]\n", rc);
1683 goto out;
1684 }
1685 }
1686 (*tfm) = key_tfm->key_tfm;
1687 (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1688 out:
1689 mutex_unlock(&key_tfm_list_mutex);
1690 return rc;
1691 }
1692
1693 /* 64 characters forming a 6-bit target field */
1694 static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
1695 "EFGHIJKLMNOPQRST"
1696 "UVWXYZabcdefghij"
1697 "klmnopqrstuvwxyz");
1698
1699 /* We could either offset on every reverse map or just pad some 0x00's
1700 * at the front here */
1701 static const unsigned char filename_rev_map[256] = {
1702 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
1703 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
1704 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
1705 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
1706 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
1707 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
1708 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
1709 0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
1710 0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
1711 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
1712 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
1713 0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
1714 0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
1715 0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
1716 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
1717 0x3D, 0x3E, 0x3F /* 123 - 255 initialized to 0x00 */
1718 };
1719
1720 /**
1721 * ecryptfs_encode_for_filename
1722 * @dst: Destination location for encoded filename
1723 * @dst_size: Size of the encoded filename in bytes
1724 * @src: Source location for the filename to encode
1725 * @src_size: Size of the source in bytes
1726 */
1727 static void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
1728 unsigned char *src, size_t src_size)
1729 {
1730 size_t num_blocks;
1731 size_t block_num = 0;
1732 size_t dst_offset = 0;
1733 unsigned char last_block[3];
1734
1735 if (src_size == 0) {
1736 (*dst_size) = 0;
1737 goto out;
1738 }
1739 num_blocks = (src_size / 3);
1740 if ((src_size % 3) == 0) {
1741 memcpy(last_block, (&src[src_size - 3]), 3);
1742 } else {
1743 num_blocks++;
1744 last_block[2] = 0x00;
1745 switch (src_size % 3) {
1746 case 1:
1747 last_block[0] = src[src_size - 1];
1748 last_block[1] = 0x00;
1749 break;
1750 case 2:
1751 last_block[0] = src[src_size - 2];
1752 last_block[1] = src[src_size - 1];
1753 }
1754 }
1755 (*dst_size) = (num_blocks * 4);
1756 if (!dst)
1757 goto out;
1758 while (block_num < num_blocks) {
1759 unsigned char *src_block;
1760 unsigned char dst_block[4];
1761
1762 if (block_num == (num_blocks - 1))
1763 src_block = last_block;
1764 else
1765 src_block = &src[block_num * 3];
1766 dst_block[0] = ((src_block[0] >> 2) & 0x3F);
1767 dst_block[1] = (((src_block[0] << 4) & 0x30)
1768 | ((src_block[1] >> 4) & 0x0F));
1769 dst_block[2] = (((src_block[1] << 2) & 0x3C)
1770 | ((src_block[2] >> 6) & 0x03));
1771 dst_block[3] = (src_block[2] & 0x3F);
1772 dst[dst_offset++] = portable_filename_chars[dst_block[0]];
1773 dst[dst_offset++] = portable_filename_chars[dst_block[1]];
1774 dst[dst_offset++] = portable_filename_chars[dst_block[2]];
1775 dst[dst_offset++] = portable_filename_chars[dst_block[3]];
1776 block_num++;
1777 }
1778 out:
1779 return;
1780 }
1781
1782 static size_t ecryptfs_max_decoded_size(size_t encoded_size)
1783 {
1784 /* Not exact; conservatively long. Every block of 4
1785 * encoded characters decodes into a block of 3
1786 * decoded characters. This segment of code provides
1787 * the caller with the maximum amount of allocated
1788 * space that @dst will need to point to in a
1789 * subsequent call. */
1790 return ((encoded_size + 1) * 3) / 4;
1791 }
1792
1793 /**
1794 * ecryptfs_decode_from_filename
1795 * @dst: If NULL, this function only sets @dst_size and returns. If
1796 * non-NULL, this function decodes the encoded octets in @src
1797 * into the memory that @dst points to.
1798 * @dst_size: Set to the size of the decoded string.
1799 * @src: The encoded set of octets to decode.
1800 * @src_size: The size of the encoded set of octets to decode.
1801 */
1802 static void
1803 ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
1804 const unsigned char *src, size_t src_size)
1805 {
1806 u8 current_bit_offset = 0;
1807 size_t src_byte_offset = 0;
1808 size_t dst_byte_offset = 0;
1809
1810 if (!dst) {
1811 (*dst_size) = ecryptfs_max_decoded_size(src_size);
1812 goto out;
1813 }
1814 while (src_byte_offset < src_size) {
1815 unsigned char src_byte =
1816 filename_rev_map[(int)src[src_byte_offset]];
1817
1818 switch (current_bit_offset) {
1819 case 0:
1820 dst[dst_byte_offset] = (src_byte << 2);
1821 current_bit_offset = 6;
1822 break;
1823 case 6:
1824 dst[dst_byte_offset++] |= (src_byte >> 4);
1825 dst[dst_byte_offset] = ((src_byte & 0xF)
1826 << 4);
1827 current_bit_offset = 4;
1828 break;
1829 case 4:
1830 dst[dst_byte_offset++] |= (src_byte >> 2);
1831 dst[dst_byte_offset] = (src_byte << 6);
1832 current_bit_offset = 2;
1833 break;
1834 case 2:
1835 dst[dst_byte_offset++] |= (src_byte);
1836 current_bit_offset = 0;
1837 break;
1838 }
1839 src_byte_offset++;
1840 }
1841 (*dst_size) = dst_byte_offset;
1842 out:
1843 return;
1844 }
1845
1846 /**
1847 * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
1848 * @encoded_name: The encrypted name
1849 * @encoded_name_size: Length of the encrypted name
1850 * @mount_crypt_stat: The crypt_stat struct associated with the file name to encode
1851 * @name: The plaintext name
1852 * @name_size: The length of the plaintext name
1853 *
1854 * Encrypts and encodes a filename into something that constitutes a
1855 * valid filename for a filesystem, with printable characters.
1856 *
1857 * We assume that we have a properly initialized crypto context,
1858 * pointed to by crypt_stat->tfm.
1859 *
1860 * Returns zero on success; non-zero on otherwise
1861 */
1862 int ecryptfs_encrypt_and_encode_filename(
1863 char **encoded_name,
1864 size_t *encoded_name_size,
1865 struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
1866 const char *name, size_t name_size)
1867 {
1868 size_t encoded_name_no_prefix_size;
1869 int rc = 0;
1870
1871 (*encoded_name) = NULL;
1872 (*encoded_name_size) = 0;
1873 if (mount_crypt_stat && (mount_crypt_stat->flags
1874 & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
1875 struct ecryptfs_filename *filename;
1876
1877 filename = kzalloc(sizeof(*filename), GFP_KERNEL);
1878 if (!filename) {
1879 rc = -ENOMEM;
1880 goto out;
1881 }
1882 filename->filename = (char *)name;
1883 filename->filename_size = name_size;
1884 rc = ecryptfs_encrypt_filename(filename, mount_crypt_stat);
1885 if (rc) {
1886 printk(KERN_ERR "%s: Error attempting to encrypt "
1887 "filename; rc = [%d]\n", __func__, rc);
1888 kfree(filename);
1889 goto out;
1890 }
1891 ecryptfs_encode_for_filename(
1892 NULL, &encoded_name_no_prefix_size,
1893 filename->encrypted_filename,
1894 filename->encrypted_filename_size);
1895 if (mount_crypt_stat
1896 && (mount_crypt_stat->flags
1897 & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))
1898 (*encoded_name_size) =
1899 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1900 + encoded_name_no_prefix_size);
1901 else
1902 (*encoded_name_size) =
1903 (ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1904 + encoded_name_no_prefix_size);
1905 (*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
1906 if (!(*encoded_name)) {
1907 rc = -ENOMEM;
1908 kfree(filename->encrypted_filename);
1909 kfree(filename);
1910 goto out;
1911 }
1912 if (mount_crypt_stat
1913 && (mount_crypt_stat->flags
1914 & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
1915 memcpy((*encoded_name),
1916 ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
1917 ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
1918 ecryptfs_encode_for_filename(
1919 ((*encoded_name)
1920 + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
1921 &encoded_name_no_prefix_size,
1922 filename->encrypted_filename,
1923 filename->encrypted_filename_size);
1924 (*encoded_name_size) =
1925 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1926 + encoded_name_no_prefix_size);
1927 (*encoded_name)[(*encoded_name_size)] = '\0';
1928 } else {
1929 rc = -EOPNOTSUPP;
1930 }
1931 if (rc) {
1932 printk(KERN_ERR "%s: Error attempting to encode "
1933 "encrypted filename; rc = [%d]\n", __func__,
1934 rc);
1935 kfree((*encoded_name));
1936 (*encoded_name) = NULL;
1937 (*encoded_name_size) = 0;
1938 }
1939 kfree(filename->encrypted_filename);
1940 kfree(filename);
1941 } else {
1942 rc = ecryptfs_copy_filename(encoded_name,
1943 encoded_name_size,
1944 name, name_size);
1945 }
1946 out:
1947 return rc;
1948 }
1949
1950 /**
1951 * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
1952 * @plaintext_name: The plaintext name
1953 * @plaintext_name_size: The plaintext name size
1954 * @sb: Ecryptfs's super_block
1955 * @name: The filename in cipher text
1956 * @name_size: The cipher text name size
1957 *
1958 * Decrypts and decodes the filename.
1959 *
1960 * Returns zero on error; non-zero otherwise
1961 */
1962 int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
1963 size_t *plaintext_name_size,
1964 struct super_block *sb,
1965 const char *name, size_t name_size)
1966 {
1967 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1968 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
1969 char *decoded_name;
1970 size_t decoded_name_size;
1971 size_t packet_size;
1972 int rc = 0;
1973
1974 if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) &&
1975 !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)) {
1976 if (is_dot_dotdot(name, name_size)) {
1977 rc = ecryptfs_copy_filename(plaintext_name,
1978 plaintext_name_size,
1979 name, name_size);
1980 goto out;
1981 }
1982
1983 if (name_size <= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE ||
1984 strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
1985 ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)) {
1986 rc = -EINVAL;
1987 goto out;
1988 }
1989
1990 name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
1991 name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
1992 ecryptfs_decode_from_filename(NULL, &decoded_name_size,
1993 name, name_size);
1994 decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
1995 if (!decoded_name) {
1996 rc = -ENOMEM;
1997 goto out;
1998 }
1999 ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2000 name, name_size);
2001 rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2002 plaintext_name_size,
2003 &packet_size,
2004 mount_crypt_stat,
2005 decoded_name,
2006 decoded_name_size);
2007 if (rc) {
2008 ecryptfs_printk(KERN_DEBUG,
2009 "%s: Could not parse tag 70 packet from filename\n",
2010 __func__);
2011 goto out_free;
2012 }
2013 } else {
2014 rc = ecryptfs_copy_filename(plaintext_name,
2015 plaintext_name_size,
2016 name, name_size);
2017 goto out;
2018 }
2019 out_free:
2020 kfree(decoded_name);
2021 out:
2022 return rc;
2023 }
2024
2025 #define ENC_NAME_MAX_BLOCKLEN_8_OR_16 143
2026
2027 int ecryptfs_set_f_namelen(long *namelen, long lower_namelen,
2028 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
2029 {
2030 struct crypto_skcipher *tfm;
2031 struct mutex *tfm_mutex;
2032 size_t cipher_blocksize;
2033 int rc;
2034
2035 if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
2036 (*namelen) = lower_namelen;
2037 return 0;
2038 }
2039
2040 rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex,
2041 mount_crypt_stat->global_default_fn_cipher_name);
2042 if (unlikely(rc)) {
2043 (*namelen) = 0;
2044 return rc;
2045 }
2046
2047 mutex_lock(tfm_mutex);
2048 cipher_blocksize = crypto_skcipher_blocksize(tfm);
2049 mutex_unlock(tfm_mutex);
2050
2051 /* Return an exact amount for the common cases */
2052 if (lower_namelen == NAME_MAX
2053 && (cipher_blocksize == 8 || cipher_blocksize == 16)) {
2054 (*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16;
2055 return 0;
2056 }
2057
2058 /* Return a safe estimate for the uncommon cases */
2059 (*namelen) = lower_namelen;
2060 (*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2061 /* Since this is the max decoded size, subtract 1 "decoded block" len */
2062 (*namelen) = ecryptfs_max_decoded_size(*namelen) - 3;
2063 (*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE;
2064 (*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES;
2065 /* Worst case is that the filename is padded nearly a full block size */
2066 (*namelen) -= cipher_blocksize - 1;
2067
2068 if ((*namelen) < 0)
2069 (*namelen) = 0;
2070
2071 return 0;
2072 }
2073
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.