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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 <linux/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 */
39void 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 */
61static 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 }
73out:
74 return rc;
75}
76
77static 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;
95out:
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 */
110int 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 }
144out:
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 */
154int 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 */
185void 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
199void 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 */
232int 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 */
274static 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);
320out:
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 */
330static loff_t lower_offset_for_page(struct ecryptfs_crypt_stat *crypt_stat,
331 struct folio *folio)
332{
333 return ecryptfs_lower_header_size(crypt_stat) +
334 (loff_t)folio->index * PAGE_SIZE;
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 * @page_index: The offset in the file (in units of PAGE_SIZE)
344 * @extent_offset: Page extent offset for use in generating IV
345 * @op: ENCRYPT or DECRYPT to indicate the desired operation
346 *
347 * Encrypts or decrypts one extent of data.
348 *
349 * Return zero on success; non-zero otherwise
350 */
351static int crypt_extent(struct ecryptfs_crypt_stat *crypt_stat,
352 struct page *dst_page,
353 struct page *src_page,
354 pgoff_t page_index,
355 unsigned long extent_offset, int op)
356{
357 loff_t extent_base;
358 char extent_iv[ECRYPTFS_MAX_IV_BYTES];
359 struct scatterlist src_sg, dst_sg;
360 size_t extent_size = crypt_stat->extent_size;
361 int rc;
362
363 extent_base = (((loff_t)page_index) * (PAGE_SIZE / extent_size));
364 rc = ecryptfs_derive_iv(extent_iv, crypt_stat,
365 (extent_base + extent_offset));
366 if (rc) {
367 ecryptfs_printk(KERN_ERR, "Error attempting to derive IV for "
368 "extent [0x%.16llx]; rc = [%d]\n",
369 (unsigned long long)(extent_base + extent_offset), rc);
370 goto out;
371 }
372
373 sg_init_table(&src_sg, 1);
374 sg_init_table(&dst_sg, 1);
375
376 sg_set_page(&src_sg, src_page, extent_size,
377 extent_offset * extent_size);
378 sg_set_page(&dst_sg, dst_page, extent_size,
379 extent_offset * extent_size);
380
381 rc = crypt_scatterlist(crypt_stat, &dst_sg, &src_sg, extent_size,
382 extent_iv, op);
383 if (rc < 0) {
384 printk(KERN_ERR "%s: Error attempting to crypt page with "
385 "page_index = [%ld], extent_offset = [%ld]; "
386 "rc = [%d]\n", __func__, page_index, extent_offset, rc);
387 goto out;
388 }
389 rc = 0;
390out:
391 return rc;
392}
393
394/**
395 * ecryptfs_encrypt_page
396 * @folio: Folio mapped from the eCryptfs inode for the file; contains
397 * decrypted content that needs to be encrypted (to a temporary
398 * page; not in place) and written out to the lower file
399 *
400 * Encrypt an eCryptfs page. This is done on a per-extent basis. Note
401 * that eCryptfs pages may straddle the lower pages -- for instance,
402 * if the file was created on a machine with an 8K page size
403 * (resulting in an 8K header), and then the file is copied onto a
404 * host with a 32K page size, then when reading page 0 of the eCryptfs
405 * file, 24K of page 0 of the lower file will be read and decrypted,
406 * and then 8K of page 1 of the lower file will be read and decrypted.
407 *
408 * Returns zero on success; negative on error
409 */
410int ecryptfs_encrypt_page(struct folio *folio)
411{
412 struct inode *ecryptfs_inode;
413 struct ecryptfs_crypt_stat *crypt_stat;
414 char *enc_extent_virt;
415 struct page *enc_extent_page = NULL;
416 loff_t extent_offset;
417 loff_t lower_offset;
418 int rc = 0;
419
420 ecryptfs_inode = folio->mapping->host;
421 crypt_stat =
422 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
423 BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
424 enc_extent_page = alloc_page(GFP_USER);
425 if (!enc_extent_page) {
426 rc = -ENOMEM;
427 ecryptfs_printk(KERN_ERR, "Error allocating memory for "
428 "encrypted extent\n");
429 goto out;
430 }
431
432 for (extent_offset = 0;
433 extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
434 extent_offset++) {
435 rc = crypt_extent(crypt_stat, enc_extent_page,
436 folio_page(folio, 0), folio->index,
437 extent_offset, ENCRYPT);
438 if (rc) {
439 printk(KERN_ERR "%s: Error encrypting extent; "
440 "rc = [%d]\n", __func__, rc);
441 goto out;
442 }
443 }
444
445 lower_offset = lower_offset_for_page(crypt_stat, folio);
446 enc_extent_virt = kmap_local_page(enc_extent_page);
447 rc = ecryptfs_write_lower(ecryptfs_inode, enc_extent_virt, lower_offset,
448 PAGE_SIZE);
449 kunmap_local(enc_extent_virt);
450 if (rc < 0) {
451 ecryptfs_printk(KERN_ERR,
452 "Error attempting to write lower page; rc = [%d]\n",
453 rc);
454 goto out;
455 }
456 rc = 0;
457out:
458 if (enc_extent_page) {
459 __free_page(enc_extent_page);
460 }
461 return rc;
462}
463
464/**
465 * ecryptfs_decrypt_page
466 * @folio: Folio mapped from the eCryptfs inode for the file; data read
467 * and decrypted from the lower file will be written into this
468 * page
469 *
470 * Decrypt an eCryptfs page. This is done on a per-extent basis. Note
471 * that eCryptfs pages may straddle the lower pages -- for instance,
472 * if the file was created on a machine with an 8K page size
473 * (resulting in an 8K header), and then the file is copied onto a
474 * host with a 32K page size, then when reading page 0 of the eCryptfs
475 * file, 24K of page 0 of the lower file will be read and decrypted,
476 * and then 8K of page 1 of the lower file will be read and decrypted.
477 *
478 * Returns zero on success; negative on error
479 */
480int ecryptfs_decrypt_page(struct folio *folio)
481{
482 struct inode *ecryptfs_inode;
483 struct ecryptfs_crypt_stat *crypt_stat;
484 char *page_virt;
485 unsigned long extent_offset;
486 loff_t lower_offset;
487 int rc = 0;
488
489 ecryptfs_inode = folio->mapping->host;
490 crypt_stat =
491 &(ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat);
492 BUG_ON(!(crypt_stat->flags & ECRYPTFS_ENCRYPTED));
493
494 lower_offset = lower_offset_for_page(crypt_stat, folio);
495 page_virt = kmap_local_folio(folio, 0);
496 rc = ecryptfs_read_lower(page_virt, lower_offset, PAGE_SIZE,
497 ecryptfs_inode);
498 kunmap_local(page_virt);
499 if (rc < 0) {
500 ecryptfs_printk(KERN_ERR,
501 "Error attempting to read lower page; rc = [%d]\n",
502 rc);
503 goto out;
504 }
505
506 for (extent_offset = 0;
507 extent_offset < (PAGE_SIZE / crypt_stat->extent_size);
508 extent_offset++) {
509 struct page *page = folio_page(folio, 0);
510 rc = crypt_extent(crypt_stat, page, page, folio->index,
511 extent_offset, DECRYPT);
512 if (rc) {
513 printk(KERN_ERR "%s: Error decrypting extent; "
514 "rc = [%d]\n", __func__, rc);
515 goto out;
516 }
517 }
518out:
519 return rc;
520}
521
522#define ECRYPTFS_MAX_SCATTERLIST_LEN 4
523
524/**
525 * ecryptfs_init_crypt_ctx
526 * @crypt_stat: Uninitialized crypt stats structure
527 *
528 * Initialize the crypto context.
529 *
530 * TODO: Performance: Keep a cache of initialized cipher contexts;
531 * only init if needed
532 */
533int ecryptfs_init_crypt_ctx(struct ecryptfs_crypt_stat *crypt_stat)
534{
535 char *full_alg_name;
536 int rc = -EINVAL;
537
538 ecryptfs_printk(KERN_DEBUG,
539 "Initializing cipher [%s]; strlen = [%d]; "
540 "key_size_bits = [%zd]\n",
541 crypt_stat->cipher, (int)strlen(crypt_stat->cipher),
542 crypt_stat->key_size << 3);
543 mutex_lock(&crypt_stat->cs_tfm_mutex);
544 if (crypt_stat->tfm) {
545 rc = 0;
546 goto out_unlock;
547 }
548 rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
549 crypt_stat->cipher, "cbc");
550 if (rc)
551 goto out_unlock;
552 crypt_stat->tfm = crypto_alloc_skcipher(full_alg_name, 0, 0);
553 if (IS_ERR(crypt_stat->tfm)) {
554 rc = PTR_ERR(crypt_stat->tfm);
555 crypt_stat->tfm = NULL;
556 ecryptfs_printk(KERN_ERR, "cryptfs: init_crypt_ctx(): "
557 "Error initializing cipher [%s]\n",
558 full_alg_name);
559 goto out_free;
560 }
561 crypto_skcipher_set_flags(crypt_stat->tfm,
562 CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
563 rc = 0;
564out_free:
565 kfree(full_alg_name);
566out_unlock:
567 mutex_unlock(&crypt_stat->cs_tfm_mutex);
568 return rc;
569}
570
571static void set_extent_mask_and_shift(struct ecryptfs_crypt_stat *crypt_stat)
572{
573 int extent_size_tmp;
574
575 crypt_stat->extent_mask = 0xFFFFFFFF;
576 crypt_stat->extent_shift = 0;
577 if (crypt_stat->extent_size == 0)
578 return;
579 extent_size_tmp = crypt_stat->extent_size;
580 while ((extent_size_tmp & 0x01) == 0) {
581 extent_size_tmp >>= 1;
582 crypt_stat->extent_mask <<= 1;
583 crypt_stat->extent_shift++;
584 }
585}
586
587void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat)
588{
589 /* Default values; may be overwritten as we are parsing the
590 * packets. */
591 crypt_stat->extent_size = ECRYPTFS_DEFAULT_EXTENT_SIZE;
592 set_extent_mask_and_shift(crypt_stat);
593 crypt_stat->iv_bytes = ECRYPTFS_DEFAULT_IV_BYTES;
594 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
595 crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
596 else {
597 if (PAGE_SIZE <= ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)
598 crypt_stat->metadata_size =
599 ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
600 else
601 crypt_stat->metadata_size = PAGE_SIZE;
602 }
603}
604
605/*
606 * ecryptfs_compute_root_iv
607 *
608 * On error, sets the root IV to all 0's.
609 */
610int ecryptfs_compute_root_iv(struct ecryptfs_crypt_stat *crypt_stat)
611{
612 int rc = 0;
613 char dst[MD5_DIGEST_SIZE];
614
615 BUG_ON(crypt_stat->iv_bytes > MD5_DIGEST_SIZE);
616 BUG_ON(crypt_stat->iv_bytes <= 0);
617 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
618 rc = -EINVAL;
619 ecryptfs_printk(KERN_WARNING, "Session key not valid; "
620 "cannot generate root IV\n");
621 goto out;
622 }
623 rc = ecryptfs_calculate_md5(dst, crypt_stat, crypt_stat->key,
624 crypt_stat->key_size);
625 if (rc) {
626 ecryptfs_printk(KERN_WARNING, "Error attempting to compute "
627 "MD5 while generating root IV\n");
628 goto out;
629 }
630 memcpy(crypt_stat->root_iv, dst, crypt_stat->iv_bytes);
631out:
632 if (rc) {
633 memset(crypt_stat->root_iv, 0, crypt_stat->iv_bytes);
634 crypt_stat->flags |= ECRYPTFS_SECURITY_WARNING;
635 }
636 return rc;
637}
638
639static void ecryptfs_generate_new_key(struct ecryptfs_crypt_stat *crypt_stat)
640{
641 get_random_bytes(crypt_stat->key, crypt_stat->key_size);
642 crypt_stat->flags |= ECRYPTFS_KEY_VALID;
643 ecryptfs_compute_root_iv(crypt_stat);
644 if (unlikely(ecryptfs_verbosity > 0)) {
645 ecryptfs_printk(KERN_DEBUG, "Generated new session key:\n");
646 ecryptfs_dump_hex(crypt_stat->key,
647 crypt_stat->key_size);
648 }
649}
650
651/**
652 * ecryptfs_copy_mount_wide_flags_to_inode_flags
653 * @crypt_stat: The inode's cryptographic context
654 * @mount_crypt_stat: The mount point's cryptographic context
655 *
656 * This function propagates the mount-wide flags to individual inode
657 * flags.
658 */
659static void ecryptfs_copy_mount_wide_flags_to_inode_flags(
660 struct ecryptfs_crypt_stat *crypt_stat,
661 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
662{
663 if (mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED)
664 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
665 if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
666 crypt_stat->flags |= ECRYPTFS_VIEW_AS_ENCRYPTED;
667 if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
668 crypt_stat->flags |= ECRYPTFS_ENCRYPT_FILENAMES;
669 if (mount_crypt_stat->flags
670 & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)
671 crypt_stat->flags |= ECRYPTFS_ENCFN_USE_MOUNT_FNEK;
672 else if (mount_crypt_stat->flags
673 & ECRYPTFS_GLOBAL_ENCFN_USE_FEK)
674 crypt_stat->flags |= ECRYPTFS_ENCFN_USE_FEK;
675 }
676}
677
678static int ecryptfs_copy_mount_wide_sigs_to_inode_sigs(
679 struct ecryptfs_crypt_stat *crypt_stat,
680 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
681{
682 struct ecryptfs_global_auth_tok *global_auth_tok;
683 int rc = 0;
684
685 mutex_lock(&crypt_stat->keysig_list_mutex);
686 mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
687
688 list_for_each_entry(global_auth_tok,
689 &mount_crypt_stat->global_auth_tok_list,
690 mount_crypt_stat_list) {
691 if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_FNEK)
692 continue;
693 rc = ecryptfs_add_keysig(crypt_stat, global_auth_tok->sig);
694 if (rc) {
695 printk(KERN_ERR "Error adding keysig; rc = [%d]\n", rc);
696 goto out;
697 }
698 }
699
700out:
701 mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
702 mutex_unlock(&crypt_stat->keysig_list_mutex);
703 return rc;
704}
705
706/**
707 * ecryptfs_set_default_crypt_stat_vals
708 * @crypt_stat: The inode's cryptographic context
709 * @mount_crypt_stat: The mount point's cryptographic context
710 *
711 * Default values in the event that policy does not override them.
712 */
713static void ecryptfs_set_default_crypt_stat_vals(
714 struct ecryptfs_crypt_stat *crypt_stat,
715 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
716{
717 ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
718 mount_crypt_stat);
719 ecryptfs_set_default_sizes(crypt_stat);
720 strcpy(crypt_stat->cipher, ECRYPTFS_DEFAULT_CIPHER);
721 crypt_stat->key_size = ECRYPTFS_DEFAULT_KEY_BYTES;
722 crypt_stat->flags &= ~(ECRYPTFS_KEY_VALID);
723 crypt_stat->file_version = ECRYPTFS_FILE_VERSION;
724 crypt_stat->mount_crypt_stat = mount_crypt_stat;
725}
726
727/**
728 * ecryptfs_new_file_context
729 * @ecryptfs_inode: The eCryptfs inode
730 *
731 * If the crypto context for the file has not yet been established,
732 * this is where we do that. Establishing a new crypto context
733 * involves the following decisions:
734 * - What cipher to use?
735 * - What set of authentication tokens to use?
736 * Here we just worry about getting enough information into the
737 * authentication tokens so that we know that they are available.
738 * We associate the available authentication tokens with the new file
739 * via the set of signatures in the crypt_stat struct. Later, when
740 * the headers are actually written out, we may again defer to
741 * userspace to perform the encryption of the session key; for the
742 * foreseeable future, this will be the case with public key packets.
743 *
744 * Returns zero on success; non-zero otherwise
745 */
746int ecryptfs_new_file_context(struct inode *ecryptfs_inode)
747{
748 struct ecryptfs_crypt_stat *crypt_stat =
749 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
750 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
751 &ecryptfs_superblock_to_private(
752 ecryptfs_inode->i_sb)->mount_crypt_stat;
753 int cipher_name_len;
754 int rc = 0;
755
756 ecryptfs_set_default_crypt_stat_vals(crypt_stat, mount_crypt_stat);
757 crypt_stat->flags |= (ECRYPTFS_ENCRYPTED | ECRYPTFS_KEY_VALID);
758 ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
759 mount_crypt_stat);
760 rc = ecryptfs_copy_mount_wide_sigs_to_inode_sigs(crypt_stat,
761 mount_crypt_stat);
762 if (rc) {
763 printk(KERN_ERR "Error attempting to copy mount-wide key sigs "
764 "to the inode key sigs; rc = [%d]\n", rc);
765 goto out;
766 }
767 cipher_name_len =
768 strlen(mount_crypt_stat->global_default_cipher_name);
769 memcpy(crypt_stat->cipher,
770 mount_crypt_stat->global_default_cipher_name,
771 cipher_name_len);
772 crypt_stat->cipher[cipher_name_len] = '\0';
773 crypt_stat->key_size =
774 mount_crypt_stat->global_default_cipher_key_size;
775 ecryptfs_generate_new_key(crypt_stat);
776 rc = ecryptfs_init_crypt_ctx(crypt_stat);
777 if (rc)
778 ecryptfs_printk(KERN_ERR, "Error initializing cryptographic "
779 "context for cipher [%s]: rc = [%d]\n",
780 crypt_stat->cipher, rc);
781out:
782 return rc;
783}
784
785/**
786 * ecryptfs_validate_marker - check for the ecryptfs marker
787 * @data: The data block in which to check
788 *
789 * Returns zero if marker found; -EINVAL if not found
790 */
791static int ecryptfs_validate_marker(char *data)
792{
793 u32 m_1, m_2;
794
795 m_1 = get_unaligned_be32(data);
796 m_2 = get_unaligned_be32(data + 4);
797 if ((m_1 ^ MAGIC_ECRYPTFS_MARKER) == m_2)
798 return 0;
799 ecryptfs_printk(KERN_DEBUG, "m_1 = [0x%.8x]; m_2 = [0x%.8x]; "
800 "MAGIC_ECRYPTFS_MARKER = [0x%.8x]\n", m_1, m_2,
801 MAGIC_ECRYPTFS_MARKER);
802 ecryptfs_printk(KERN_DEBUG, "(m_1 ^ MAGIC_ECRYPTFS_MARKER) = "
803 "[0x%.8x]\n", (m_1 ^ MAGIC_ECRYPTFS_MARKER));
804 return -EINVAL;
805}
806
807struct ecryptfs_flag_map_elem {
808 u32 file_flag;
809 u32 local_flag;
810};
811
812/* Add support for additional flags by adding elements here. */
813static struct ecryptfs_flag_map_elem ecryptfs_flag_map[] = {
814 {0x00000001, ECRYPTFS_ENABLE_HMAC},
815 {0x00000002, ECRYPTFS_ENCRYPTED},
816 {0x00000004, ECRYPTFS_METADATA_IN_XATTR},
817 {0x00000008, ECRYPTFS_ENCRYPT_FILENAMES}
818};
819
820/**
821 * ecryptfs_process_flags
822 * @crypt_stat: The cryptographic context
823 * @page_virt: Source data to be parsed
824 * @bytes_read: Updated with the number of bytes read
825 */
826static void ecryptfs_process_flags(struct ecryptfs_crypt_stat *crypt_stat,
827 char *page_virt, int *bytes_read)
828{
829 int i;
830 u32 flags;
831
832 flags = get_unaligned_be32(page_virt);
833 for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++)
834 if (flags & ecryptfs_flag_map[i].file_flag) {
835 crypt_stat->flags |= ecryptfs_flag_map[i].local_flag;
836 } else
837 crypt_stat->flags &= ~(ecryptfs_flag_map[i].local_flag);
838 /* Version is in top 8 bits of the 32-bit flag vector */
839 crypt_stat->file_version = ((flags >> 24) & 0xFF);
840 (*bytes_read) = 4;
841}
842
843/**
844 * write_ecryptfs_marker
845 * @page_virt: The pointer to in a page to begin writing the marker
846 * @written: Number of bytes written
847 *
848 * Marker = 0x3c81b7f5
849 */
850static void write_ecryptfs_marker(char *page_virt, size_t *written)
851{
852 u32 m_1, m_2;
853
854 get_random_bytes(&m_1, (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2));
855 m_2 = (m_1 ^ MAGIC_ECRYPTFS_MARKER);
856 put_unaligned_be32(m_1, page_virt);
857 page_virt += (MAGIC_ECRYPTFS_MARKER_SIZE_BYTES / 2);
858 put_unaligned_be32(m_2, page_virt);
859 (*written) = MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
860}
861
862void ecryptfs_write_crypt_stat_flags(char *page_virt,
863 struct ecryptfs_crypt_stat *crypt_stat,
864 size_t *written)
865{
866 u32 flags = 0;
867 int i;
868
869 for (i = 0; i < ARRAY_SIZE(ecryptfs_flag_map); i++)
870 if (crypt_stat->flags & ecryptfs_flag_map[i].local_flag)
871 flags |= ecryptfs_flag_map[i].file_flag;
872 /* Version is in top 8 bits of the 32-bit flag vector */
873 flags |= ((((u8)crypt_stat->file_version) << 24) & 0xFF000000);
874 put_unaligned_be32(flags, page_virt);
875 (*written) = 4;
876}
877
878struct ecryptfs_cipher_code_str_map_elem {
879 char cipher_str[16];
880 u8 cipher_code;
881};
882
883/* Add support for additional ciphers by adding elements here. The
884 * cipher_code is whatever OpenPGP applications use to identify the
885 * ciphers. List in order of probability. */
886static struct ecryptfs_cipher_code_str_map_elem
887ecryptfs_cipher_code_str_map[] = {
888 {"aes",RFC2440_CIPHER_AES_128 },
889 {"blowfish", RFC2440_CIPHER_BLOWFISH},
890 {"des3_ede", RFC2440_CIPHER_DES3_EDE},
891 {"cast5", RFC2440_CIPHER_CAST_5},
892 {"twofish", RFC2440_CIPHER_TWOFISH},
893 {"cast6", RFC2440_CIPHER_CAST_6},
894 {"aes", RFC2440_CIPHER_AES_192},
895 {"aes", RFC2440_CIPHER_AES_256}
896};
897
898/**
899 * ecryptfs_code_for_cipher_string
900 * @cipher_name: The string alias for the cipher
901 * @key_bytes: Length of key in bytes; used for AES code selection
902 *
903 * Returns zero on no match, or the cipher code on match
904 */
905u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
906{
907 int i;
908 u8 code = 0;
909 struct ecryptfs_cipher_code_str_map_elem *map =
910 ecryptfs_cipher_code_str_map;
911
912 if (strcmp(cipher_name, "aes") == 0) {
913 switch (key_bytes) {
914 case 16:
915 code = RFC2440_CIPHER_AES_128;
916 break;
917 case 24:
918 code = RFC2440_CIPHER_AES_192;
919 break;
920 case 32:
921 code = RFC2440_CIPHER_AES_256;
922 }
923 } else {
924 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
925 if (strcmp(cipher_name, map[i].cipher_str) == 0) {
926 code = map[i].cipher_code;
927 break;
928 }
929 }
930 return code;
931}
932
933/**
934 * ecryptfs_cipher_code_to_string
935 * @str: Destination to write out the cipher name
936 * @cipher_code: The code to convert to cipher name string
937 *
938 * Returns zero on success
939 */
940int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code)
941{
942 int rc = 0;
943 int i;
944
945 str[0] = '\0';
946 for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
947 if (cipher_code == ecryptfs_cipher_code_str_map[i].cipher_code)
948 strcpy(str, ecryptfs_cipher_code_str_map[i].cipher_str);
949 if (str[0] == '\0') {
950 ecryptfs_printk(KERN_WARNING, "Cipher code not recognized: "
951 "[%d]\n", cipher_code);
952 rc = -EINVAL;
953 }
954 return rc;
955}
956
957int ecryptfs_read_and_validate_header_region(struct inode *inode)
958{
959 u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
960 u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
961 int rc;
962
963 rc = ecryptfs_read_lower(file_size, 0, ECRYPTFS_SIZE_AND_MARKER_BYTES,
964 inode);
965 if (rc < 0)
966 return rc;
967 else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
968 return -EINVAL;
969 rc = ecryptfs_validate_marker(marker);
970 if (!rc)
971 ecryptfs_i_size_init(file_size, inode);
972 return rc;
973}
974
975void
976ecryptfs_write_header_metadata(char *virt,
977 struct ecryptfs_crypt_stat *crypt_stat,
978 size_t *written)
979{
980 u32 header_extent_size;
981 u16 num_header_extents_at_front;
982
983 header_extent_size = (u32)crypt_stat->extent_size;
984 num_header_extents_at_front =
985 (u16)(crypt_stat->metadata_size / crypt_stat->extent_size);
986 put_unaligned_be32(header_extent_size, virt);
987 virt += 4;
988 put_unaligned_be16(num_header_extents_at_front, virt);
989 (*written) = 6;
990}
991
992struct kmem_cache *ecryptfs_header_cache;
993
994/**
995 * ecryptfs_write_headers_virt
996 * @page_virt: The virtual address to write the headers to
997 * @max: The size of memory allocated at page_virt
998 * @size: Set to the number of bytes written by this function
999 * @crypt_stat: The cryptographic context
1000 * @ecryptfs_dentry: The eCryptfs dentry
1001 *
1002 * Format version: 1
1003 *
1004 * Header Extent:
1005 * Octets 0-7: Unencrypted file size (big-endian)
1006 * Octets 8-15: eCryptfs special marker
1007 * Octets 16-19: Flags
1008 * Octet 16: File format version number (between 0 and 255)
1009 * Octets 17-18: Reserved
1010 * Octet 19: Bit 1 (lsb): Reserved
1011 * Bit 2: Encrypted?
1012 * Bits 3-8: Reserved
1013 * Octets 20-23: Header extent size (big-endian)
1014 * Octets 24-25: Number of header extents at front of file
1015 * (big-endian)
1016 * Octet 26: Begin RFC 2440 authentication token packet set
1017 * Data Extent 0:
1018 * Lower data (CBC encrypted)
1019 * Data Extent 1:
1020 * Lower data (CBC encrypted)
1021 * ...
1022 *
1023 * Returns zero on success
1024 */
1025static int ecryptfs_write_headers_virt(char *page_virt, size_t max,
1026 size_t *size,
1027 struct ecryptfs_crypt_stat *crypt_stat,
1028 struct dentry *ecryptfs_dentry)
1029{
1030 int rc;
1031 size_t written;
1032 size_t offset;
1033
1034 offset = ECRYPTFS_FILE_SIZE_BYTES;
1035 write_ecryptfs_marker((page_virt + offset), &written);
1036 offset += written;
1037 ecryptfs_write_crypt_stat_flags((page_virt + offset), crypt_stat,
1038 &written);
1039 offset += written;
1040 ecryptfs_write_header_metadata((page_virt + offset), crypt_stat,
1041 &written);
1042 offset += written;
1043 rc = ecryptfs_generate_key_packet_set((page_virt + offset), crypt_stat,
1044 ecryptfs_dentry, &written,
1045 max - offset);
1046 if (rc)
1047 ecryptfs_printk(KERN_WARNING, "Error generating key packet "
1048 "set; rc = [%d]\n", rc);
1049 if (size) {
1050 offset += written;
1051 *size = offset;
1052 }
1053 return rc;
1054}
1055
1056static int
1057ecryptfs_write_metadata_to_contents(struct inode *ecryptfs_inode,
1058 char *virt, size_t virt_len)
1059{
1060 int rc;
1061
1062 rc = ecryptfs_write_lower(ecryptfs_inode, virt,
1063 0, virt_len);
1064 if (rc < 0)
1065 printk(KERN_ERR "%s: Error attempting to write header "
1066 "information to lower file; rc = [%d]\n", __func__, rc);
1067 else
1068 rc = 0;
1069 return rc;
1070}
1071
1072static int
1073ecryptfs_write_metadata_to_xattr(struct dentry *ecryptfs_dentry,
1074 struct inode *ecryptfs_inode,
1075 char *page_virt, size_t size)
1076{
1077 int rc;
1078 struct dentry *lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
1079 struct inode *lower_inode = d_inode(lower_dentry);
1080
1081 if (!(lower_inode->i_opflags & IOP_XATTR)) {
1082 rc = -EOPNOTSUPP;
1083 goto out;
1084 }
1085
1086 inode_lock(lower_inode);
1087 rc = __vfs_setxattr(&nop_mnt_idmap, lower_dentry, lower_inode,
1088 ECRYPTFS_XATTR_NAME, page_virt, size, 0);
1089 if (!rc && ecryptfs_inode)
1090 fsstack_copy_attr_all(ecryptfs_inode, lower_inode);
1091 inode_unlock(lower_inode);
1092out:
1093 return rc;
1094}
1095
1096static unsigned long ecryptfs_get_zeroed_pages(gfp_t gfp_mask,
1097 unsigned int order)
1098{
1099 struct page *page;
1100
1101 page = alloc_pages(gfp_mask | __GFP_ZERO, order);
1102 if (page)
1103 return (unsigned long) page_address(page);
1104 return 0;
1105}
1106
1107/**
1108 * ecryptfs_write_metadata
1109 * @ecryptfs_dentry: The eCryptfs dentry, which should be negative
1110 * @ecryptfs_inode: The newly created eCryptfs inode
1111 *
1112 * Write the file headers out. This will likely involve a userspace
1113 * callout, in which the session key is encrypted with one or more
1114 * public keys and/or the passphrase necessary to do the encryption is
1115 * retrieved via a prompt. Exactly what happens at this point should
1116 * be policy-dependent.
1117 *
1118 * Returns zero on success; non-zero on error
1119 */
1120int ecryptfs_write_metadata(struct dentry *ecryptfs_dentry,
1121 struct inode *ecryptfs_inode)
1122{
1123 struct ecryptfs_crypt_stat *crypt_stat =
1124 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1125 unsigned int order;
1126 char *virt;
1127 size_t virt_len;
1128 size_t size = 0;
1129 int rc = 0;
1130
1131 if (likely(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
1132 if (!(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
1133 printk(KERN_ERR "Key is invalid; bailing out\n");
1134 rc = -EINVAL;
1135 goto out;
1136 }
1137 } else {
1138 printk(KERN_WARNING "%s: Encrypted flag not set\n",
1139 __func__);
1140 rc = -EINVAL;
1141 goto out;
1142 }
1143 virt_len = crypt_stat->metadata_size;
1144 order = get_order(virt_len);
1145 /* Released in this function */
1146 virt = (char *)ecryptfs_get_zeroed_pages(GFP_KERNEL, order);
1147 if (!virt) {
1148 printk(KERN_ERR "%s: Out of memory\n", __func__);
1149 rc = -ENOMEM;
1150 goto out;
1151 }
1152 /* Zeroed page ensures the in-header unencrypted i_size is set to 0 */
1153 rc = ecryptfs_write_headers_virt(virt, virt_len, &size, crypt_stat,
1154 ecryptfs_dentry);
1155 if (unlikely(rc)) {
1156 printk(KERN_ERR "%s: Error whilst writing headers; rc = [%d]\n",
1157 __func__, rc);
1158 goto out_free;
1159 }
1160 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1161 rc = ecryptfs_write_metadata_to_xattr(ecryptfs_dentry, ecryptfs_inode,
1162 virt, size);
1163 else
1164 rc = ecryptfs_write_metadata_to_contents(ecryptfs_inode, virt,
1165 virt_len);
1166 if (rc) {
1167 printk(KERN_ERR "%s: Error writing metadata out to lower file; "
1168 "rc = [%d]\n", __func__, rc);
1169 goto out_free;
1170 }
1171out_free:
1172 free_pages((unsigned long)virt, order);
1173out:
1174 return rc;
1175}
1176
1177#define ECRYPTFS_DONT_VALIDATE_HEADER_SIZE 0
1178#define ECRYPTFS_VALIDATE_HEADER_SIZE 1
1179static int parse_header_metadata(struct ecryptfs_crypt_stat *crypt_stat,
1180 char *virt, int *bytes_read,
1181 int validate_header_size)
1182{
1183 int rc = 0;
1184 u32 header_extent_size;
1185 u16 num_header_extents_at_front;
1186
1187 header_extent_size = get_unaligned_be32(virt);
1188 virt += sizeof(__be32);
1189 num_header_extents_at_front = get_unaligned_be16(virt);
1190 crypt_stat->metadata_size = (((size_t)num_header_extents_at_front
1191 * (size_t)header_extent_size));
1192 (*bytes_read) = (sizeof(__be32) + sizeof(__be16));
1193 if ((validate_header_size == ECRYPTFS_VALIDATE_HEADER_SIZE)
1194 && (crypt_stat->metadata_size
1195 < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE)) {
1196 rc = -EINVAL;
1197 printk(KERN_WARNING "Invalid header size: [%zd]\n",
1198 crypt_stat->metadata_size);
1199 }
1200 return rc;
1201}
1202
1203/**
1204 * set_default_header_data
1205 * @crypt_stat: The cryptographic context
1206 *
1207 * For version 0 file format; this function is only for backwards
1208 * compatibility for files created with the prior versions of
1209 * eCryptfs.
1210 */
1211static void set_default_header_data(struct ecryptfs_crypt_stat *crypt_stat)
1212{
1213 crypt_stat->metadata_size = ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE;
1214}
1215
1216void ecryptfs_i_size_init(const char *page_virt, struct inode *inode)
1217{
1218 struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
1219 struct ecryptfs_crypt_stat *crypt_stat;
1220 u64 file_size;
1221
1222 crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
1223 mount_crypt_stat =
1224 &ecryptfs_superblock_to_private(inode->i_sb)->mount_crypt_stat;
1225 if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
1226 file_size = i_size_read(ecryptfs_inode_to_lower(inode));
1227 if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
1228 file_size += crypt_stat->metadata_size;
1229 } else
1230 file_size = get_unaligned_be64(page_virt);
1231 i_size_write(inode, (loff_t)file_size);
1232 crypt_stat->flags |= ECRYPTFS_I_SIZE_INITIALIZED;
1233}
1234
1235/**
1236 * ecryptfs_read_headers_virt
1237 * @page_virt: The virtual address into which to read the headers
1238 * @crypt_stat: The cryptographic context
1239 * @ecryptfs_dentry: The eCryptfs dentry
1240 * @validate_header_size: Whether to validate the header size while reading
1241 *
1242 * Read/parse the header data. The header format is detailed in the
1243 * comment block for the ecryptfs_write_headers_virt() function.
1244 *
1245 * Returns zero on success
1246 */
1247static int ecryptfs_read_headers_virt(char *page_virt,
1248 struct ecryptfs_crypt_stat *crypt_stat,
1249 struct dentry *ecryptfs_dentry,
1250 int validate_header_size)
1251{
1252 int rc = 0;
1253 int offset;
1254 int bytes_read;
1255
1256 ecryptfs_set_default_sizes(crypt_stat);
1257 crypt_stat->mount_crypt_stat = &ecryptfs_superblock_to_private(
1258 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1259 offset = ECRYPTFS_FILE_SIZE_BYTES;
1260 rc = ecryptfs_validate_marker(page_virt + offset);
1261 if (rc)
1262 goto out;
1263 if (!(crypt_stat->flags & ECRYPTFS_I_SIZE_INITIALIZED))
1264 ecryptfs_i_size_init(page_virt, d_inode(ecryptfs_dentry));
1265 offset += MAGIC_ECRYPTFS_MARKER_SIZE_BYTES;
1266 ecryptfs_process_flags(crypt_stat, (page_virt + offset), &bytes_read);
1267 if (crypt_stat->file_version > ECRYPTFS_SUPPORTED_FILE_VERSION) {
1268 ecryptfs_printk(KERN_WARNING, "File version is [%d]; only "
1269 "file version [%d] is supported by this "
1270 "version of eCryptfs\n",
1271 crypt_stat->file_version,
1272 ECRYPTFS_SUPPORTED_FILE_VERSION);
1273 rc = -EINVAL;
1274 goto out;
1275 }
1276 offset += bytes_read;
1277 if (crypt_stat->file_version >= 1) {
1278 rc = parse_header_metadata(crypt_stat, (page_virt + offset),
1279 &bytes_read, validate_header_size);
1280 if (rc) {
1281 ecryptfs_printk(KERN_WARNING, "Error reading header "
1282 "metadata; rc = [%d]\n", rc);
1283 }
1284 offset += bytes_read;
1285 } else
1286 set_default_header_data(crypt_stat);
1287 rc = ecryptfs_parse_packet_set(crypt_stat, (page_virt + offset),
1288 ecryptfs_dentry);
1289out:
1290 return rc;
1291}
1292
1293/**
1294 * ecryptfs_read_xattr_region
1295 * @page_virt: The vitual address into which to read the xattr data
1296 * @ecryptfs_inode: The eCryptfs inode
1297 *
1298 * Attempts to read the crypto metadata from the extended attribute
1299 * region of the lower file.
1300 *
1301 * Returns zero on success; non-zero on error
1302 */
1303int ecryptfs_read_xattr_region(char *page_virt, struct inode *ecryptfs_inode)
1304{
1305 struct dentry *lower_dentry =
1306 ecryptfs_inode_to_private(ecryptfs_inode)->lower_file->f_path.dentry;
1307 ssize_t size;
1308 int rc = 0;
1309
1310 size = ecryptfs_getxattr_lower(lower_dentry,
1311 ecryptfs_inode_to_lower(ecryptfs_inode),
1312 ECRYPTFS_XATTR_NAME,
1313 page_virt, ECRYPTFS_DEFAULT_EXTENT_SIZE);
1314 if (size < 0) {
1315 if (unlikely(ecryptfs_verbosity > 0))
1316 printk(KERN_INFO "Error attempting to read the [%s] "
1317 "xattr from the lower file; return value = "
1318 "[%zd]\n", ECRYPTFS_XATTR_NAME, size);
1319 rc = -EINVAL;
1320 goto out;
1321 }
1322out:
1323 return rc;
1324}
1325
1326int ecryptfs_read_and_validate_xattr_region(struct dentry *dentry,
1327 struct inode *inode)
1328{
1329 u8 file_size[ECRYPTFS_SIZE_AND_MARKER_BYTES];
1330 u8 *marker = file_size + ECRYPTFS_FILE_SIZE_BYTES;
1331 int rc;
1332
1333 rc = ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry),
1334 ecryptfs_inode_to_lower(inode),
1335 ECRYPTFS_XATTR_NAME, file_size,
1336 ECRYPTFS_SIZE_AND_MARKER_BYTES);
1337 if (rc < 0)
1338 return rc;
1339 else if (rc < ECRYPTFS_SIZE_AND_MARKER_BYTES)
1340 return -EINVAL;
1341 rc = ecryptfs_validate_marker(marker);
1342 if (!rc)
1343 ecryptfs_i_size_init(file_size, inode);
1344 return rc;
1345}
1346
1347/*
1348 * ecryptfs_read_metadata
1349 *
1350 * Common entry point for reading file metadata. From here, we could
1351 * retrieve the header information from the header region of the file,
1352 * the xattr region of the file, or some other repository that is
1353 * stored separately from the file itself. The current implementation
1354 * supports retrieving the metadata information from the file contents
1355 * and from the xattr region.
1356 *
1357 * Returns zero if valid headers found and parsed; non-zero otherwise
1358 */
1359int ecryptfs_read_metadata(struct dentry *ecryptfs_dentry)
1360{
1361 int rc;
1362 char *page_virt;
1363 struct inode *ecryptfs_inode = d_inode(ecryptfs_dentry);
1364 struct ecryptfs_crypt_stat *crypt_stat =
1365 &ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
1366 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1367 &ecryptfs_superblock_to_private(
1368 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1369
1370 ecryptfs_copy_mount_wide_flags_to_inode_flags(crypt_stat,
1371 mount_crypt_stat);
1372 /* Read the first page from the underlying file */
1373 page_virt = kmem_cache_alloc(ecryptfs_header_cache, GFP_USER);
1374 if (!page_virt) {
1375 rc = -ENOMEM;
1376 goto out;
1377 }
1378 rc = ecryptfs_read_lower(page_virt, 0, crypt_stat->extent_size,
1379 ecryptfs_inode);
1380 if (rc >= 0)
1381 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1382 ecryptfs_dentry,
1383 ECRYPTFS_VALIDATE_HEADER_SIZE);
1384 if (rc) {
1385 /* metadata is not in the file header, so try xattrs */
1386 memset(page_virt, 0, PAGE_SIZE);
1387 rc = ecryptfs_read_xattr_region(page_virt, ecryptfs_inode);
1388 if (rc) {
1389 printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1390 "file header region or xattr region, inode %lu\n",
1391 ecryptfs_inode->i_ino);
1392 rc = -EINVAL;
1393 goto out;
1394 }
1395 rc = ecryptfs_read_headers_virt(page_virt, crypt_stat,
1396 ecryptfs_dentry,
1397 ECRYPTFS_DONT_VALIDATE_HEADER_SIZE);
1398 if (rc) {
1399 printk(KERN_DEBUG "Valid eCryptfs headers not found in "
1400 "file xattr region either, inode %lu\n",
1401 ecryptfs_inode->i_ino);
1402 rc = -EINVAL;
1403 }
1404 if (crypt_stat->mount_crypt_stat->flags
1405 & ECRYPTFS_XATTR_METADATA_ENABLED) {
1406 crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
1407 } else {
1408 printk(KERN_WARNING "Attempt to access file with "
1409 "crypto metadata only in the extended attribute "
1410 "region, but eCryptfs was mounted without "
1411 "xattr support enabled. eCryptfs will not treat "
1412 "this like an encrypted file, inode %lu\n",
1413 ecryptfs_inode->i_ino);
1414 rc = -EINVAL;
1415 }
1416 }
1417out:
1418 if (page_virt) {
1419 memset(page_virt, 0, PAGE_SIZE);
1420 kmem_cache_free(ecryptfs_header_cache, page_virt);
1421 }
1422 return rc;
1423}
1424
1425/*
1426 * ecryptfs_encrypt_filename - encrypt filename
1427 *
1428 * CBC-encrypts the filename. We do not want to encrypt the same
1429 * filename with the same key and IV, which may happen with hard
1430 * links, so we prepend random bits to each filename.
1431 *
1432 * Returns zero on success; non-zero otherwise
1433 */
1434static int
1435ecryptfs_encrypt_filename(struct ecryptfs_filename *filename,
1436 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
1437{
1438 int rc = 0;
1439
1440 filename->encrypted_filename = NULL;
1441 filename->encrypted_filename_size = 0;
1442 if (mount_crypt_stat && (mount_crypt_stat->flags
1443 & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
1444 size_t packet_size;
1445 size_t remaining_bytes;
1446
1447 rc = ecryptfs_write_tag_70_packet(
1448 NULL, NULL,
1449 &filename->encrypted_filename_size,
1450 mount_crypt_stat, NULL,
1451 filename->filename_size);
1452 if (rc) {
1453 printk(KERN_ERR "%s: Error attempting to get packet "
1454 "size for tag 72; rc = [%d]\n", __func__,
1455 rc);
1456 filename->encrypted_filename_size = 0;
1457 goto out;
1458 }
1459 filename->encrypted_filename =
1460 kmalloc(filename->encrypted_filename_size, GFP_KERNEL);
1461 if (!filename->encrypted_filename) {
1462 rc = -ENOMEM;
1463 goto out;
1464 }
1465 remaining_bytes = filename->encrypted_filename_size;
1466 rc = ecryptfs_write_tag_70_packet(filename->encrypted_filename,
1467 &remaining_bytes,
1468 &packet_size,
1469 mount_crypt_stat,
1470 filename->filename,
1471 filename->filename_size);
1472 if (rc) {
1473 printk(KERN_ERR "%s: Error attempting to generate "
1474 "tag 70 packet; rc = [%d]\n", __func__,
1475 rc);
1476 kfree(filename->encrypted_filename);
1477 filename->encrypted_filename = NULL;
1478 filename->encrypted_filename_size = 0;
1479 goto out;
1480 }
1481 filename->encrypted_filename_size = packet_size;
1482 } else {
1483 printk(KERN_ERR "%s: No support for requested filename "
1484 "encryption method in this release\n", __func__);
1485 rc = -EOPNOTSUPP;
1486 goto out;
1487 }
1488out:
1489 return rc;
1490}
1491
1492static int ecryptfs_copy_filename(char **copied_name, size_t *copied_name_size,
1493 const char *name, size_t name_size)
1494{
1495 int rc = 0;
1496
1497 (*copied_name) = kmalloc((name_size + 1), GFP_KERNEL);
1498 if (!(*copied_name)) {
1499 rc = -ENOMEM;
1500 goto out;
1501 }
1502 memcpy((void *)(*copied_name), (void *)name, name_size);
1503 (*copied_name)[(name_size)] = '\0'; /* Only for convenience
1504 * in printing out the
1505 * string in debug
1506 * messages */
1507 (*copied_name_size) = name_size;
1508out:
1509 return rc;
1510}
1511
1512/**
1513 * ecryptfs_process_key_cipher - Perform key cipher initialization.
1514 * @key_tfm: Crypto context for key material, set by this function
1515 * @cipher_name: Name of the cipher
1516 * @key_size: Size of the key in bytes
1517 *
1518 * Returns zero on success. Any crypto_tfm structs allocated here
1519 * should be released by other functions, such as on a superblock put
1520 * event, regardless of whether this function succeeds for fails.
1521 */
1522static int
1523ecryptfs_process_key_cipher(struct crypto_skcipher **key_tfm,
1524 char *cipher_name, size_t *key_size)
1525{
1526 char dummy_key[ECRYPTFS_MAX_KEY_BYTES];
1527 char *full_alg_name = NULL;
1528 int rc;
1529
1530 *key_tfm = NULL;
1531 if (*key_size > ECRYPTFS_MAX_KEY_BYTES) {
1532 rc = -EINVAL;
1533 printk(KERN_ERR "Requested key size is [%zd] bytes; maximum "
1534 "allowable is [%d]\n", *key_size, ECRYPTFS_MAX_KEY_BYTES);
1535 goto out;
1536 }
1537 rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name, cipher_name,
1538 "ecb");
1539 if (rc)
1540 goto out;
1541 *key_tfm = crypto_alloc_skcipher(full_alg_name, 0, CRYPTO_ALG_ASYNC);
1542 if (IS_ERR(*key_tfm)) {
1543 rc = PTR_ERR(*key_tfm);
1544 printk(KERN_ERR "Unable to allocate crypto cipher with name "
1545 "[%s]; rc = [%d]\n", full_alg_name, rc);
1546 goto out;
1547 }
1548 crypto_skcipher_set_flags(*key_tfm, CRYPTO_TFM_REQ_FORBID_WEAK_KEYS);
1549 if (*key_size == 0)
1550 *key_size = crypto_skcipher_max_keysize(*key_tfm);
1551 get_random_bytes(dummy_key, *key_size);
1552 rc = crypto_skcipher_setkey(*key_tfm, dummy_key, *key_size);
1553 if (rc) {
1554 printk(KERN_ERR "Error attempting to set key of size [%zd] for "
1555 "cipher [%s]; rc = [%d]\n", *key_size, full_alg_name,
1556 rc);
1557 rc = -EINVAL;
1558 goto out;
1559 }
1560out:
1561 kfree(full_alg_name);
1562 return rc;
1563}
1564
1565struct kmem_cache *ecryptfs_key_tfm_cache;
1566static struct list_head key_tfm_list;
1567DEFINE_MUTEX(key_tfm_list_mutex);
1568
1569int __init ecryptfs_init_crypto(void)
1570{
1571 INIT_LIST_HEAD(&key_tfm_list);
1572 return 0;
1573}
1574
1575/**
1576 * ecryptfs_destroy_crypto - free all cached key_tfms on key_tfm_list
1577 *
1578 * Called only at module unload time
1579 */
1580int ecryptfs_destroy_crypto(void)
1581{
1582 struct ecryptfs_key_tfm *key_tfm, *key_tfm_tmp;
1583
1584 mutex_lock(&key_tfm_list_mutex);
1585 list_for_each_entry_safe(key_tfm, key_tfm_tmp, &key_tfm_list,
1586 key_tfm_list) {
1587 list_del(&key_tfm->key_tfm_list);
1588 crypto_free_skcipher(key_tfm->key_tfm);
1589 kmem_cache_free(ecryptfs_key_tfm_cache, key_tfm);
1590 }
1591 mutex_unlock(&key_tfm_list_mutex);
1592 return 0;
1593}
1594
1595int
1596ecryptfs_add_new_key_tfm(struct ecryptfs_key_tfm **key_tfm, char *cipher_name,
1597 size_t key_size)
1598{
1599 struct ecryptfs_key_tfm *tmp_tfm;
1600 int rc = 0;
1601
1602 BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1603
1604 tmp_tfm = kmem_cache_alloc(ecryptfs_key_tfm_cache, GFP_KERNEL);
1605 if (key_tfm)
1606 (*key_tfm) = tmp_tfm;
1607 if (!tmp_tfm) {
1608 rc = -ENOMEM;
1609 goto out;
1610 }
1611 mutex_init(&tmp_tfm->key_tfm_mutex);
1612 strscpy(tmp_tfm->cipher_name, cipher_name);
1613 tmp_tfm->key_size = key_size;
1614 rc = ecryptfs_process_key_cipher(&tmp_tfm->key_tfm,
1615 tmp_tfm->cipher_name,
1616 &tmp_tfm->key_size);
1617 if (rc) {
1618 printk(KERN_ERR "Error attempting to initialize key TFM "
1619 "cipher with name = [%s]; rc = [%d]\n",
1620 tmp_tfm->cipher_name, rc);
1621 kmem_cache_free(ecryptfs_key_tfm_cache, tmp_tfm);
1622 if (key_tfm)
1623 (*key_tfm) = NULL;
1624 goto out;
1625 }
1626 list_add(&tmp_tfm->key_tfm_list, &key_tfm_list);
1627out:
1628 return rc;
1629}
1630
1631/**
1632 * ecryptfs_tfm_exists - Search for existing tfm for cipher_name.
1633 * @cipher_name: the name of the cipher to search for
1634 * @key_tfm: set to corresponding tfm if found
1635 *
1636 * Searches for cached key_tfm matching @cipher_name
1637 * Must be called with &key_tfm_list_mutex held
1638 * Returns 1 if found, with @key_tfm set
1639 * Returns 0 if not found, with @key_tfm set to NULL
1640 */
1641int ecryptfs_tfm_exists(char *cipher_name, struct ecryptfs_key_tfm **key_tfm)
1642{
1643 struct ecryptfs_key_tfm *tmp_key_tfm;
1644
1645 BUG_ON(!mutex_is_locked(&key_tfm_list_mutex));
1646
1647 list_for_each_entry(tmp_key_tfm, &key_tfm_list, key_tfm_list) {
1648 if (strcmp(tmp_key_tfm->cipher_name, cipher_name) == 0) {
1649 if (key_tfm)
1650 (*key_tfm) = tmp_key_tfm;
1651 return 1;
1652 }
1653 }
1654 if (key_tfm)
1655 (*key_tfm) = NULL;
1656 return 0;
1657}
1658
1659/**
1660 * ecryptfs_get_tfm_and_mutex_for_cipher_name
1661 *
1662 * @tfm: set to cached tfm found, or new tfm created
1663 * @tfm_mutex: set to mutex for cached tfm found, or new tfm created
1664 * @cipher_name: the name of the cipher to search for and/or add
1665 *
1666 * Sets pointers to @tfm & @tfm_mutex matching @cipher_name.
1667 * Searches for cached item first, and creates new if not found.
1668 * Returns 0 on success, non-zero if adding new cipher failed
1669 */
1670int ecryptfs_get_tfm_and_mutex_for_cipher_name(struct crypto_skcipher **tfm,
1671 struct mutex **tfm_mutex,
1672 char *cipher_name)
1673{
1674 struct ecryptfs_key_tfm *key_tfm;
1675 int rc = 0;
1676
1677 (*tfm) = NULL;
1678 (*tfm_mutex) = NULL;
1679
1680 mutex_lock(&key_tfm_list_mutex);
1681 if (!ecryptfs_tfm_exists(cipher_name, &key_tfm)) {
1682 rc = ecryptfs_add_new_key_tfm(&key_tfm, cipher_name, 0);
1683 if (rc) {
1684 printk(KERN_ERR "Error adding new key_tfm to list; "
1685 "rc = [%d]\n", rc);
1686 goto out;
1687 }
1688 }
1689 (*tfm) = key_tfm->key_tfm;
1690 (*tfm_mutex) = &key_tfm->key_tfm_mutex;
1691out:
1692 mutex_unlock(&key_tfm_list_mutex);
1693 return rc;
1694}
1695
1696/* 64 characters forming a 6-bit target field */
1697static unsigned char *portable_filename_chars = ("-.0123456789ABCD"
1698 "EFGHIJKLMNOPQRST"
1699 "UVWXYZabcdefghij"
1700 "klmnopqrstuvwxyz");
1701
1702/* We could either offset on every reverse map or just pad some 0x00's
1703 * at the front here */
1704static const unsigned char filename_rev_map[256] = {
1705 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 7 */
1706 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 15 */
1707 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 23 */
1708 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 31 */
1709 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 39 */
1710 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, /* 47 */
1711 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, /* 55 */
1712 0x0A, 0x0B, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, /* 63 */
1713 0x00, 0x0C, 0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, /* 71 */
1714 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1A, /* 79 */
1715 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20, 0x21, 0x22, /* 87 */
1716 0x23, 0x24, 0x25, 0x00, 0x00, 0x00, 0x00, 0x00, /* 95 */
1717 0x00, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0x2C, /* 103 */
1718 0x2D, 0x2E, 0x2F, 0x30, 0x31, 0x32, 0x33, 0x34, /* 111 */
1719 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, /* 119 */
1720 0x3D, 0x3E, 0x3F /* 123 - 255 initialized to 0x00 */
1721};
1722
1723/**
1724 * ecryptfs_encode_for_filename
1725 * @dst: Destination location for encoded filename
1726 * @dst_size: Size of the encoded filename in bytes
1727 * @src: Source location for the filename to encode
1728 * @src_size: Size of the source in bytes
1729 */
1730static void ecryptfs_encode_for_filename(unsigned char *dst, size_t *dst_size,
1731 unsigned char *src, size_t src_size)
1732{
1733 size_t num_blocks;
1734 size_t block_num = 0;
1735 size_t dst_offset = 0;
1736 unsigned char last_block[3];
1737
1738 if (src_size == 0) {
1739 (*dst_size) = 0;
1740 goto out;
1741 }
1742 num_blocks = (src_size / 3);
1743 if ((src_size % 3) == 0) {
1744 memcpy(last_block, (&src[src_size - 3]), 3);
1745 } else {
1746 num_blocks++;
1747 last_block[2] = 0x00;
1748 switch (src_size % 3) {
1749 case 1:
1750 last_block[0] = src[src_size - 1];
1751 last_block[1] = 0x00;
1752 break;
1753 case 2:
1754 last_block[0] = src[src_size - 2];
1755 last_block[1] = src[src_size - 1];
1756 }
1757 }
1758 (*dst_size) = (num_blocks * 4);
1759 if (!dst)
1760 goto out;
1761 while (block_num < num_blocks) {
1762 unsigned char *src_block;
1763 unsigned char dst_block[4];
1764
1765 if (block_num == (num_blocks - 1))
1766 src_block = last_block;
1767 else
1768 src_block = &src[block_num * 3];
1769 dst_block[0] = ((src_block[0] >> 2) & 0x3F);
1770 dst_block[1] = (((src_block[0] << 4) & 0x30)
1771 | ((src_block[1] >> 4) & 0x0F));
1772 dst_block[2] = (((src_block[1] << 2) & 0x3C)
1773 | ((src_block[2] >> 6) & 0x03));
1774 dst_block[3] = (src_block[2] & 0x3F);
1775 dst[dst_offset++] = portable_filename_chars[dst_block[0]];
1776 dst[dst_offset++] = portable_filename_chars[dst_block[1]];
1777 dst[dst_offset++] = portable_filename_chars[dst_block[2]];
1778 dst[dst_offset++] = portable_filename_chars[dst_block[3]];
1779 block_num++;
1780 }
1781out:
1782 return;
1783}
1784
1785static size_t ecryptfs_max_decoded_size(size_t encoded_size)
1786{
1787 /* Not exact; conservatively long. Every block of 4
1788 * encoded characters decodes into a block of 3
1789 * decoded characters. This segment of code provides
1790 * the caller with the maximum amount of allocated
1791 * space that @dst will need to point to in a
1792 * subsequent call. */
1793 return ((encoded_size + 1) * 3) / 4;
1794}
1795
1796/**
1797 * ecryptfs_decode_from_filename
1798 * @dst: If NULL, this function only sets @dst_size and returns. If
1799 * non-NULL, this function decodes the encoded octets in @src
1800 * into the memory that @dst points to.
1801 * @dst_size: Set to the size of the decoded string.
1802 * @src: The encoded set of octets to decode.
1803 * @src_size: The size of the encoded set of octets to decode.
1804 */
1805static void
1806ecryptfs_decode_from_filename(unsigned char *dst, size_t *dst_size,
1807 const unsigned char *src, size_t src_size)
1808{
1809 u8 current_bit_offset = 0;
1810 size_t src_byte_offset = 0;
1811 size_t dst_byte_offset = 0;
1812
1813 if (!dst) {
1814 (*dst_size) = ecryptfs_max_decoded_size(src_size);
1815 goto out;
1816 }
1817 while (src_byte_offset < src_size) {
1818 unsigned char src_byte =
1819 filename_rev_map[(int)src[src_byte_offset]];
1820
1821 switch (current_bit_offset) {
1822 case 0:
1823 dst[dst_byte_offset] = (src_byte << 2);
1824 current_bit_offset = 6;
1825 break;
1826 case 6:
1827 dst[dst_byte_offset++] |= (src_byte >> 4);
1828 dst[dst_byte_offset] = ((src_byte & 0xF)
1829 << 4);
1830 current_bit_offset = 4;
1831 break;
1832 case 4:
1833 dst[dst_byte_offset++] |= (src_byte >> 2);
1834 dst[dst_byte_offset] = (src_byte << 6);
1835 current_bit_offset = 2;
1836 break;
1837 case 2:
1838 dst[dst_byte_offset++] |= (src_byte);
1839 current_bit_offset = 0;
1840 break;
1841 }
1842 src_byte_offset++;
1843 }
1844 (*dst_size) = dst_byte_offset;
1845out:
1846 return;
1847}
1848
1849/**
1850 * ecryptfs_encrypt_and_encode_filename - converts a plaintext file name to cipher text
1851 * @encoded_name: The encrypted name
1852 * @encoded_name_size: Length of the encrypted name
1853 * @mount_crypt_stat: The crypt_stat struct associated with the file name to encode
1854 * @name: The plaintext name
1855 * @name_size: The length of the plaintext name
1856 *
1857 * Encrypts and encodes a filename into something that constitutes a
1858 * valid filename for a filesystem, with printable characters.
1859 *
1860 * We assume that we have a properly initialized crypto context,
1861 * pointed to by crypt_stat->tfm.
1862 *
1863 * Returns zero on success; non-zero on otherwise
1864 */
1865int ecryptfs_encrypt_and_encode_filename(
1866 char **encoded_name,
1867 size_t *encoded_name_size,
1868 struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
1869 const char *name, size_t name_size)
1870{
1871 size_t encoded_name_no_prefix_size;
1872 int rc = 0;
1873
1874 (*encoded_name) = NULL;
1875 (*encoded_name_size) = 0;
1876 if (mount_crypt_stat && (mount_crypt_stat->flags
1877 & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
1878 struct ecryptfs_filename *filename;
1879
1880 filename = kzalloc(sizeof(*filename), GFP_KERNEL);
1881 if (!filename) {
1882 rc = -ENOMEM;
1883 goto out;
1884 }
1885 filename->filename = (char *)name;
1886 filename->filename_size = name_size;
1887 rc = ecryptfs_encrypt_filename(filename, mount_crypt_stat);
1888 if (rc) {
1889 printk(KERN_ERR "%s: Error attempting to encrypt "
1890 "filename; rc = [%d]\n", __func__, rc);
1891 kfree(filename);
1892 goto out;
1893 }
1894 ecryptfs_encode_for_filename(
1895 NULL, &encoded_name_no_prefix_size,
1896 filename->encrypted_filename,
1897 filename->encrypted_filename_size);
1898 if (mount_crypt_stat
1899 && (mount_crypt_stat->flags
1900 & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK))
1901 (*encoded_name_size) =
1902 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1903 + encoded_name_no_prefix_size);
1904 else
1905 (*encoded_name_size) =
1906 (ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1907 + encoded_name_no_prefix_size);
1908 (*encoded_name) = kmalloc((*encoded_name_size) + 1, GFP_KERNEL);
1909 if (!(*encoded_name)) {
1910 rc = -ENOMEM;
1911 kfree(filename->encrypted_filename);
1912 kfree(filename);
1913 goto out;
1914 }
1915 if (mount_crypt_stat
1916 && (mount_crypt_stat->flags
1917 & ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK)) {
1918 memcpy((*encoded_name),
1919 ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
1920 ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE);
1921 ecryptfs_encode_for_filename(
1922 ((*encoded_name)
1923 + ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE),
1924 &encoded_name_no_prefix_size,
1925 filename->encrypted_filename,
1926 filename->encrypted_filename_size);
1927 (*encoded_name_size) =
1928 (ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE
1929 + encoded_name_no_prefix_size);
1930 (*encoded_name)[(*encoded_name_size)] = '\0';
1931 } else {
1932 rc = -EOPNOTSUPP;
1933 }
1934 if (rc) {
1935 printk(KERN_ERR "%s: Error attempting to encode "
1936 "encrypted filename; rc = [%d]\n", __func__,
1937 rc);
1938 kfree((*encoded_name));
1939 (*encoded_name) = NULL;
1940 (*encoded_name_size) = 0;
1941 }
1942 kfree(filename->encrypted_filename);
1943 kfree(filename);
1944 } else {
1945 rc = ecryptfs_copy_filename(encoded_name,
1946 encoded_name_size,
1947 name, name_size);
1948 }
1949out:
1950 return rc;
1951}
1952
1953/**
1954 * ecryptfs_decode_and_decrypt_filename - converts the encoded cipher text name to decoded plaintext
1955 * @plaintext_name: The plaintext name
1956 * @plaintext_name_size: The plaintext name size
1957 * @sb: Ecryptfs's super_block
1958 * @name: The filename in cipher text
1959 * @name_size: The cipher text name size
1960 *
1961 * Decrypts and decodes the filename.
1962 *
1963 * Returns zero on error; non-zero otherwise
1964 */
1965int ecryptfs_decode_and_decrypt_filename(char **plaintext_name,
1966 size_t *plaintext_name_size,
1967 struct super_block *sb,
1968 const char *name, size_t name_size)
1969{
1970 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1971 &ecryptfs_superblock_to_private(sb)->mount_crypt_stat;
1972 char *decoded_name;
1973 size_t decoded_name_size;
1974 size_t packet_size;
1975 int rc = 0;
1976
1977 if ((mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) &&
1978 !(mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)) {
1979 if (is_dot_dotdot(name, name_size)) {
1980 rc = ecryptfs_copy_filename(plaintext_name,
1981 plaintext_name_size,
1982 name, name_size);
1983 goto out;
1984 }
1985
1986 if (name_size <= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE ||
1987 strncmp(name, ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX,
1988 ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE)) {
1989 rc = -EINVAL;
1990 goto out;
1991 }
1992
1993 name += ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
1994 name_size -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
1995 ecryptfs_decode_from_filename(NULL, &decoded_name_size,
1996 name, name_size);
1997 decoded_name = kmalloc(decoded_name_size, GFP_KERNEL);
1998 if (!decoded_name) {
1999 rc = -ENOMEM;
2000 goto out;
2001 }
2002 ecryptfs_decode_from_filename(decoded_name, &decoded_name_size,
2003 name, name_size);
2004 rc = ecryptfs_parse_tag_70_packet(plaintext_name,
2005 plaintext_name_size,
2006 &packet_size,
2007 mount_crypt_stat,
2008 decoded_name,
2009 decoded_name_size);
2010 if (rc) {
2011 ecryptfs_printk(KERN_DEBUG,
2012 "%s: Could not parse tag 70 packet from filename\n",
2013 __func__);
2014 goto out_free;
2015 }
2016 } else {
2017 rc = ecryptfs_copy_filename(plaintext_name,
2018 plaintext_name_size,
2019 name, name_size);
2020 goto out;
2021 }
2022out_free:
2023 kfree(decoded_name);
2024out:
2025 return rc;
2026}
2027
2028#define ENC_NAME_MAX_BLOCKLEN_8_OR_16 143
2029
2030int ecryptfs_set_f_namelen(long *namelen, long lower_namelen,
2031 struct ecryptfs_mount_crypt_stat *mount_crypt_stat)
2032{
2033 struct crypto_skcipher *tfm;
2034 struct mutex *tfm_mutex;
2035 size_t cipher_blocksize;
2036 int rc;
2037
2038 if (!(mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)) {
2039 (*namelen) = lower_namelen;
2040 return 0;
2041 }
2042
2043 rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex,
2044 mount_crypt_stat->global_default_fn_cipher_name);
2045 if (unlikely(rc)) {
2046 (*namelen) = 0;
2047 return rc;
2048 }
2049
2050 mutex_lock(tfm_mutex);
2051 cipher_blocksize = crypto_skcipher_blocksize(tfm);
2052 mutex_unlock(tfm_mutex);
2053
2054 /* Return an exact amount for the common cases */
2055 if (lower_namelen == NAME_MAX
2056 && (cipher_blocksize == 8 || cipher_blocksize == 16)) {
2057 (*namelen) = ENC_NAME_MAX_BLOCKLEN_8_OR_16;
2058 return 0;
2059 }
2060
2061 /* Return a safe estimate for the uncommon cases */
2062 (*namelen) = lower_namelen;
2063 (*namelen) -= ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE;
2064 /* Since this is the max decoded size, subtract 1 "decoded block" len */
2065 (*namelen) = ecryptfs_max_decoded_size(*namelen) - 3;
2066 (*namelen) -= ECRYPTFS_TAG_70_MAX_METADATA_SIZE;
2067 (*namelen) -= ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES;
2068 /* Worst case is that the filename is padded nearly a full block size */
2069 (*namelen) -= cipher_blocksize - 1;
2070
2071 if ((*namelen) < 0)
2072 (*namelen) = 0;
2073
2074 return 0;
2075}