projects/linux·blob master · refs

1975 lines · 57.7 KiB

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