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-rw-r--r--fs/ecryptfs/keystore.c1061
1 files changed, 1061 insertions, 0 deletions
diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c
new file mode 100644
index 000000000000..ba454785a0c5
--- /dev/null
+++ b/fs/ecryptfs/keystore.c
@@ -0,0 +1,1061 @@
1/**
2 * eCryptfs: Linux filesystem encryption layer
3 * In-kernel key management code. Includes functions to parse and
4 * write authentication token-related packets with the underlying
5 * file.
6 *
7 * Copyright (C) 2004-2006 International Business Machines Corp.
8 * Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
9 * Michael C. Thompson <mcthomps@us.ibm.com>
10 *
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License as
13 * published by the Free Software Foundation; either version 2 of the
14 * License, or (at your option) any later version.
15 *
16 * This program is distributed in the hope that it will be useful, but
17 * WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 * General Public License for more details.
20 *
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software
23 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
24 * 02111-1307, USA.
25 */
26
27#include <linux/string.h>
28#include <linux/sched.h>
29#include <linux/syscalls.h>
30#include <linux/pagemap.h>
31#include <linux/key.h>
32#include <linux/random.h>
33#include <linux/crypto.h>
34#include <linux/scatterlist.h>
35#include "ecryptfs_kernel.h"
36
37/**
38 * request_key returned an error instead of a valid key address;
39 * determine the type of error, make appropriate log entries, and
40 * return an error code.
41 */
42int process_request_key_err(long err_code)
43{
44 int rc = 0;
45
46 switch (err_code) {
47 case ENOKEY:
48 ecryptfs_printk(KERN_WARNING, "No key\n");
49 rc = -ENOENT;
50 break;
51 case EKEYEXPIRED:
52 ecryptfs_printk(KERN_WARNING, "Key expired\n");
53 rc = -ETIME;
54 break;
55 case EKEYREVOKED:
56 ecryptfs_printk(KERN_WARNING, "Key revoked\n");
57 rc = -EINVAL;
58 break;
59 default:
60 ecryptfs_printk(KERN_WARNING, "Unknown error code: "
61 "[0x%.16x]\n", err_code);
62 rc = -EINVAL;
63 }
64 return rc;
65}
66
67static void wipe_auth_tok_list(struct list_head *auth_tok_list_head)
68{
69 struct list_head *walker;
70 struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
71
72 walker = auth_tok_list_head->next;
73 while (walker != auth_tok_list_head) {
74 auth_tok_list_item =
75 list_entry(walker, struct ecryptfs_auth_tok_list_item,
76 list);
77 walker = auth_tok_list_item->list.next;
78 memset(auth_tok_list_item, 0,
79 sizeof(struct ecryptfs_auth_tok_list_item));
80 kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
81 auth_tok_list_item);
82 }
83}
84
85struct kmem_cache *ecryptfs_auth_tok_list_item_cache;
86
87/**
88 * parse_packet_length
89 * @data: Pointer to memory containing length at offset
90 * @size: This function writes the decoded size to this memory
91 * address; zero on error
92 * @length_size: The number of bytes occupied by the encoded length
93 *
94 * Returns Zero on success
95 */
96static int parse_packet_length(unsigned char *data, size_t *size,
97 size_t *length_size)
98{
99 int rc = 0;
100
101 (*length_size) = 0;
102 (*size) = 0;
103 if (data[0] < 192) {
104 /* One-byte length */
105 (*size) = data[0];
106 (*length_size) = 1;
107 } else if (data[0] < 224) {
108 /* Two-byte length */
109 (*size) = ((data[0] - 192) * 256);
110 (*size) += (data[1] + 192);
111 (*length_size) = 2;
112 } else if (data[0] == 255) {
113 /* Five-byte length; we're not supposed to see this */
114 ecryptfs_printk(KERN_ERR, "Five-byte packet length not "
115 "supported\n");
116 rc = -EINVAL;
117 goto out;
118 } else {
119 ecryptfs_printk(KERN_ERR, "Error parsing packet length\n");
120 rc = -EINVAL;
121 goto out;
122 }
123out:
124 return rc;
125}
126
127/**
128 * write_packet_length
129 * @dest: The byte array target into which to write the
130 * length. Must have at least 5 bytes allocated.
131 * @size: The length to write.
132 * @packet_size_length: The number of bytes used to encode the
133 * packet length is written to this address.
134 *
135 * Returns zero on success; non-zero on error.
136 */
137static int write_packet_length(char *dest, size_t size,
138 size_t *packet_size_length)
139{
140 int rc = 0;
141
142 if (size < 192) {
143 dest[0] = size;
144 (*packet_size_length) = 1;
145 } else if (size < 65536) {
146 dest[0] = (((size - 192) / 256) + 192);
147 dest[1] = ((size - 192) % 256);
148 (*packet_size_length) = 2;
149 } else {
150 rc = -EINVAL;
151 ecryptfs_printk(KERN_WARNING,
152 "Unsupported packet size: [%d]\n", size);
153 }
154 return rc;
155}
156
157/**
158 * parse_tag_3_packet
159 * @crypt_stat: The cryptographic context to modify based on packet
160 * contents.
161 * @data: The raw bytes of the packet.
162 * @auth_tok_list: eCryptfs parses packets into authentication tokens;
163 * a new authentication token will be placed at the end
164 * of this list for this packet.
165 * @new_auth_tok: Pointer to a pointer to memory that this function
166 * allocates; sets the memory address of the pointer to
167 * NULL on error. This object is added to the
168 * auth_tok_list.
169 * @packet_size: This function writes the size of the parsed packet
170 * into this memory location; zero on error.
171 * @max_packet_size: maximum number of bytes to parse
172 *
173 * Returns zero on success; non-zero on error.
174 */
175static int
176parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat,
177 unsigned char *data, struct list_head *auth_tok_list,
178 struct ecryptfs_auth_tok **new_auth_tok,
179 size_t *packet_size, size_t max_packet_size)
180{
181 int rc = 0;
182 size_t body_size;
183 struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
184 size_t length_size;
185
186 (*packet_size) = 0;
187 (*new_auth_tok) = NULL;
188
189 /* we check that:
190 * one byte for the Tag 3 ID flag
191 * two bytes for the body size
192 * do not exceed the maximum_packet_size
193 */
194 if (unlikely((*packet_size) + 3 > max_packet_size)) {
195 ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
196 rc = -EINVAL;
197 goto out;
198 }
199
200 /* check for Tag 3 identifyer - one byte */
201 if (data[(*packet_size)++] != ECRYPTFS_TAG_3_PACKET_TYPE) {
202 ecryptfs_printk(KERN_ERR, "Enter w/ first byte != 0x%.2x\n",
203 ECRYPTFS_TAG_3_PACKET_TYPE);
204 rc = -EINVAL;
205 goto out;
206 }
207 /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
208 * at end of function upon failure */
209 auth_tok_list_item =
210 kmem_cache_alloc(ecryptfs_auth_tok_list_item_cache, SLAB_KERNEL);
211 if (!auth_tok_list_item) {
212 ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
213 rc = -ENOMEM;
214 goto out;
215 }
216 memset(auth_tok_list_item, 0,
217 sizeof(struct ecryptfs_auth_tok_list_item));
218 (*new_auth_tok) = &auth_tok_list_item->auth_tok;
219
220 /* check for body size - one to two bytes */
221 rc = parse_packet_length(&data[(*packet_size)], &body_size,
222 &length_size);
223 if (rc) {
224 ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
225 "rc = [%d]\n", rc);
226 goto out_free;
227 }
228 if (unlikely(body_size < (0x05 + ECRYPTFS_SALT_SIZE))) {
229 ecryptfs_printk(KERN_WARNING, "Invalid body size ([%d])\n",
230 body_size);
231 rc = -EINVAL;
232 goto out_free;
233 }
234 (*packet_size) += length_size;
235
236 /* now we know the length of the remainting Tag 3 packet size:
237 * 5 fix bytes for: version string, cipher, S2K ID, hash algo,
238 * number of hash iterations
239 * ECRYPTFS_SALT_SIZE bytes for salt
240 * body_size bytes minus the stuff above is the encrypted key size
241 */
242 if (unlikely((*packet_size) + body_size > max_packet_size)) {
243 ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
244 rc = -EINVAL;
245 goto out_free;
246 }
247
248 /* There are 5 characters of additional information in the
249 * packet */
250 (*new_auth_tok)->session_key.encrypted_key_size =
251 body_size - (0x05 + ECRYPTFS_SALT_SIZE);
252 ecryptfs_printk(KERN_DEBUG, "Encrypted key size = [%d]\n",
253 (*new_auth_tok)->session_key.encrypted_key_size);
254
255 /* Version 4 (from RFC2440) - one byte */
256 if (unlikely(data[(*packet_size)++] != 0x04)) {
257 ecryptfs_printk(KERN_DEBUG, "Unknown version number "
258 "[%d]\n", data[(*packet_size) - 1]);
259 rc = -EINVAL;
260 goto out_free;
261 }
262
263 /* cipher - one byte */
264 ecryptfs_cipher_code_to_string(crypt_stat->cipher,
265 (u16)data[(*packet_size)]);
266 /* A little extra work to differentiate among the AES key
267 * sizes; see RFC2440 */
268 switch(data[(*packet_size)++]) {
269 case RFC2440_CIPHER_AES_192:
270 crypt_stat->key_size = 24;
271 break;
272 default:
273 crypt_stat->key_size =
274 (*new_auth_tok)->session_key.encrypted_key_size;
275 }
276 ecryptfs_init_crypt_ctx(crypt_stat);
277 /* S2K identifier 3 (from RFC2440) */
278 if (unlikely(data[(*packet_size)++] != 0x03)) {
279 ecryptfs_printk(KERN_ERR, "Only S2K ID 3 is currently "
280 "supported\n");
281 rc = -ENOSYS;
282 goto out_free;
283 }
284
285 /* TODO: finish the hash mapping */
286 /* hash algorithm - one byte */
287 switch (data[(*packet_size)++]) {
288 case 0x01: /* See RFC2440 for these numbers and their mappings */
289 /* Choose MD5 */
290 /* salt - ECRYPTFS_SALT_SIZE bytes */
291 memcpy((*new_auth_tok)->token.password.salt,
292 &data[(*packet_size)], ECRYPTFS_SALT_SIZE);
293 (*packet_size) += ECRYPTFS_SALT_SIZE;
294
295 /* This conversion was taken straight from RFC2440 */
296 /* number of hash iterations - one byte */
297 (*new_auth_tok)->token.password.hash_iterations =
298 ((u32) 16 + (data[(*packet_size)] & 15))
299 << ((data[(*packet_size)] >> 4) + 6);
300 (*packet_size)++;
301
302 /* encrypted session key -
303 * (body_size-5-ECRYPTFS_SALT_SIZE) bytes */
304 memcpy((*new_auth_tok)->session_key.encrypted_key,
305 &data[(*packet_size)],
306 (*new_auth_tok)->session_key.encrypted_key_size);
307 (*packet_size) +=
308 (*new_auth_tok)->session_key.encrypted_key_size;
309 (*new_auth_tok)->session_key.flags &=
310 ~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
311 (*new_auth_tok)->session_key.flags |=
312 ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
313 (*new_auth_tok)->token.password.hash_algo = 0x01;
314 break;
315 default:
316 ecryptfs_printk(KERN_ERR, "Unsupported hash algorithm: "
317 "[%d]\n", data[(*packet_size) - 1]);
318 rc = -ENOSYS;
319 goto out_free;
320 }
321 (*new_auth_tok)->token_type = ECRYPTFS_PASSWORD;
322 /* TODO: Parametarize; we might actually want userspace to
323 * decrypt the session key. */
324 ECRYPTFS_CLEAR_FLAG((*new_auth_tok)->session_key.flags,
325 ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
326 ECRYPTFS_CLEAR_FLAG((*new_auth_tok)->session_key.flags,
327 ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
328 list_add(&auth_tok_list_item->list, auth_tok_list);
329 goto out;
330out_free:
331 (*new_auth_tok) = NULL;
332 memset(auth_tok_list_item, 0,
333 sizeof(struct ecryptfs_auth_tok_list_item));
334 kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
335 auth_tok_list_item);
336out:
337 if (rc)
338 (*packet_size) = 0;
339 return rc;
340}
341
342/**
343 * parse_tag_11_packet
344 * @data: The raw bytes of the packet
345 * @contents: This function writes the data contents of the literal
346 * packet into this memory location
347 * @max_contents_bytes: The maximum number of bytes that this function
348 * is allowed to write into contents
349 * @tag_11_contents_size: This function writes the size of the parsed
350 * contents into this memory location; zero on
351 * error
352 * @packet_size: This function writes the size of the parsed packet
353 * into this memory location; zero on error
354 * @max_packet_size: maximum number of bytes to parse
355 *
356 * Returns zero on success; non-zero on error.
357 */
358static int
359parse_tag_11_packet(unsigned char *data, unsigned char *contents,
360 size_t max_contents_bytes, size_t *tag_11_contents_size,
361 size_t *packet_size, size_t max_packet_size)
362{
363 int rc = 0;
364 size_t body_size;
365 size_t length_size;
366
367 (*packet_size) = 0;
368 (*tag_11_contents_size) = 0;
369
370 /* check that:
371 * one byte for the Tag 11 ID flag
372 * two bytes for the Tag 11 length
373 * do not exceed the maximum_packet_size
374 */
375 if (unlikely((*packet_size) + 3 > max_packet_size)) {
376 ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
377 rc = -EINVAL;
378 goto out;
379 }
380
381 /* check for Tag 11 identifyer - one byte */
382 if (data[(*packet_size)++] != ECRYPTFS_TAG_11_PACKET_TYPE) {
383 ecryptfs_printk(KERN_WARNING,
384 "Invalid tag 11 packet format\n");
385 rc = -EINVAL;
386 goto out;
387 }
388
389 /* get Tag 11 content length - one or two bytes */
390 rc = parse_packet_length(&data[(*packet_size)], &body_size,
391 &length_size);
392 if (rc) {
393 ecryptfs_printk(KERN_WARNING,
394 "Invalid tag 11 packet format\n");
395 goto out;
396 }
397 (*packet_size) += length_size;
398
399 if (body_size < 13) {
400 ecryptfs_printk(KERN_WARNING, "Invalid body size ([%d])\n",
401 body_size);
402 rc = -EINVAL;
403 goto out;
404 }
405 /* We have 13 bytes of surrounding packet values */
406 (*tag_11_contents_size) = (body_size - 13);
407
408 /* now we know the length of the remainting Tag 11 packet size:
409 * 14 fix bytes for: special flag one, special flag two,
410 * 12 skipped bytes
411 * body_size bytes minus the stuff above is the Tag 11 content
412 */
413 /* FIXME why is the body size one byte smaller than the actual
414 * size of the body?
415 * this seems to be an error here as well as in
416 * write_tag_11_packet() */
417 if (unlikely((*packet_size) + body_size + 1 > max_packet_size)) {
418 ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
419 rc = -EINVAL;
420 goto out;
421 }
422
423 /* special flag one - one byte */
424 if (data[(*packet_size)++] != 0x62) {
425 ecryptfs_printk(KERN_WARNING, "Unrecognizable packet\n");
426 rc = -EINVAL;
427 goto out;
428 }
429
430 /* special flag two - one byte */
431 if (data[(*packet_size)++] != 0x08) {
432 ecryptfs_printk(KERN_WARNING, "Unrecognizable packet\n");
433 rc = -EINVAL;
434 goto out;
435 }
436
437 /* skip the next 12 bytes */
438 (*packet_size) += 12; /* We don't care about the filename or
439 * the timestamp */
440
441 /* get the Tag 11 contents - tag_11_contents_size bytes */
442 memcpy(contents, &data[(*packet_size)], (*tag_11_contents_size));
443 (*packet_size) += (*tag_11_contents_size);
444
445out:
446 if (rc) {
447 (*packet_size) = 0;
448 (*tag_11_contents_size) = 0;
449 }
450 return rc;
451}
452
453/**
454 * decrypt_session_key - Decrypt the session key with the given auth_tok.
455 *
456 * Returns Zero on success; non-zero error otherwise.
457 */
458static int decrypt_session_key(struct ecryptfs_auth_tok *auth_tok,
459 struct ecryptfs_crypt_stat *crypt_stat)
460{
461 int rc = 0;
462 struct ecryptfs_password *password_s_ptr;
463 struct crypto_tfm *tfm = NULL;
464 struct scatterlist src_sg[2], dst_sg[2];
465 struct mutex *tfm_mutex = NULL;
466 /* TODO: Use virt_to_scatterlist for these */
467 char *encrypted_session_key;
468 char *session_key;
469
470 password_s_ptr = &auth_tok->token.password;
471 if (ECRYPTFS_CHECK_FLAG(password_s_ptr->flags,
472 ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET))
473 ecryptfs_printk(KERN_DEBUG, "Session key encryption key "
474 "set; skipping key generation\n");
475 ecryptfs_printk(KERN_DEBUG, "Session key encryption key (size [%d])"
476 ":\n",
477 password_s_ptr->session_key_encryption_key_bytes);
478 if (ecryptfs_verbosity > 0)
479 ecryptfs_dump_hex(password_s_ptr->session_key_encryption_key,
480 password_s_ptr->
481 session_key_encryption_key_bytes);
482 if (!strcmp(crypt_stat->cipher,
483 crypt_stat->mount_crypt_stat->global_default_cipher_name)
484 && crypt_stat->mount_crypt_stat->global_key_tfm) {
485 tfm = crypt_stat->mount_crypt_stat->global_key_tfm;
486 tfm_mutex = &crypt_stat->mount_crypt_stat->global_key_tfm_mutex;
487 } else {
488 tfm = crypto_alloc_tfm(crypt_stat->cipher,
489 CRYPTO_TFM_REQ_WEAK_KEY);
490 if (!tfm) {
491 printk(KERN_ERR "Error allocating crypto context\n");
492 rc = -ENOMEM;
493 goto out;
494 }
495 }
496 if (password_s_ptr->session_key_encryption_key_bytes
497 < crypto_tfm_alg_min_keysize(tfm)) {
498 printk(KERN_WARNING "Session key encryption key is [%d] bytes; "
499 "minimum keysize for selected cipher is [%d] bytes.\n",
500 password_s_ptr->session_key_encryption_key_bytes,
501 crypto_tfm_alg_min_keysize(tfm));
502 rc = -EINVAL;
503 goto out;
504 }
505 if (tfm_mutex)
506 mutex_lock(tfm_mutex);
507 crypto_cipher_setkey(tfm, password_s_ptr->session_key_encryption_key,
508 crypt_stat->key_size);
509 /* TODO: virt_to_scatterlist */
510 encrypted_session_key = (char *)__get_free_page(GFP_KERNEL);
511 if (!encrypted_session_key) {
512 ecryptfs_printk(KERN_ERR, "Out of memory\n");
513 rc = -ENOMEM;
514 goto out_free_tfm;
515 }
516 session_key = (char *)__get_free_page(GFP_KERNEL);
517 if (!session_key) {
518 kfree(encrypted_session_key);
519 ecryptfs_printk(KERN_ERR, "Out of memory\n");
520 rc = -ENOMEM;
521 goto out_free_tfm;
522 }
523 memcpy(encrypted_session_key, auth_tok->session_key.encrypted_key,
524 auth_tok->session_key.encrypted_key_size);
525 src_sg[0].page = virt_to_page(encrypted_session_key);
526 src_sg[0].offset = 0;
527 BUG_ON(auth_tok->session_key.encrypted_key_size > PAGE_CACHE_SIZE);
528 src_sg[0].length = auth_tok->session_key.encrypted_key_size;
529 dst_sg[0].page = virt_to_page(session_key);
530 dst_sg[0].offset = 0;
531 auth_tok->session_key.decrypted_key_size =
532 auth_tok->session_key.encrypted_key_size;
533 dst_sg[0].length = auth_tok->session_key.encrypted_key_size;
534 /* TODO: Handle error condition */
535 crypto_cipher_decrypt(tfm, dst_sg, src_sg,
536 auth_tok->session_key.encrypted_key_size);
537 auth_tok->session_key.decrypted_key_size =
538 auth_tok->session_key.encrypted_key_size;
539 memcpy(auth_tok->session_key.decrypted_key, session_key,
540 auth_tok->session_key.decrypted_key_size);
541 auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
542 memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
543 auth_tok->session_key.decrypted_key_size);
544 ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
545 ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n");
546 if (ecryptfs_verbosity > 0)
547 ecryptfs_dump_hex(crypt_stat->key,
548 crypt_stat->key_size);
549 memset(encrypted_session_key, 0, PAGE_CACHE_SIZE);
550 free_page((unsigned long)encrypted_session_key);
551 memset(session_key, 0, PAGE_CACHE_SIZE);
552 free_page((unsigned long)session_key);
553out_free_tfm:
554 if (tfm_mutex)
555 mutex_unlock(tfm_mutex);
556 else
557 crypto_free_tfm(tfm);
558out:
559 return rc;
560}
561
562/**
563 * ecryptfs_parse_packet_set
564 * @dest: The header page in memory
565 * @version: Version of file format, to guide parsing behavior
566 *
567 * Get crypt_stat to have the file's session key if the requisite key
568 * is available to decrypt the session key.
569 *
570 * Returns Zero if a valid authentication token was retrieved and
571 * processed; negative value for file not encrypted or for error
572 * conditions.
573 */
574int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
575 unsigned char *src,
576 struct dentry *ecryptfs_dentry)
577{
578 size_t i = 0;
579 int rc = 0;
580 size_t found_auth_tok = 0;
581 size_t next_packet_is_auth_tok_packet;
582 char sig[ECRYPTFS_SIG_SIZE_HEX];
583 struct list_head auth_tok_list;
584 struct list_head *walker;
585 struct ecryptfs_auth_tok *chosen_auth_tok = NULL;
586 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
587 &ecryptfs_superblock_to_private(
588 ecryptfs_dentry->d_sb)->mount_crypt_stat;
589 struct ecryptfs_auth_tok *candidate_auth_tok = NULL;
590 size_t packet_size;
591 struct ecryptfs_auth_tok *new_auth_tok;
592 unsigned char sig_tmp_space[ECRYPTFS_SIG_SIZE];
593 size_t tag_11_contents_size;
594 size_t tag_11_packet_size;
595
596 INIT_LIST_HEAD(&auth_tok_list);
597 /* Parse the header to find as many packets as we can, these will be
598 * added the our &auth_tok_list */
599 next_packet_is_auth_tok_packet = 1;
600 while (next_packet_is_auth_tok_packet) {
601 size_t max_packet_size = ((PAGE_CACHE_SIZE - 8) - i);
602
603 switch (src[i]) {
604 case ECRYPTFS_TAG_3_PACKET_TYPE:
605 rc = parse_tag_3_packet(crypt_stat,
606 (unsigned char *)&src[i],
607 &auth_tok_list, &new_auth_tok,
608 &packet_size, max_packet_size);
609 if (rc) {
610 ecryptfs_printk(KERN_ERR, "Error parsing "
611 "tag 3 packet\n");
612 rc = -EIO;
613 goto out_wipe_list;
614 }
615 i += packet_size;
616 rc = parse_tag_11_packet((unsigned char *)&src[i],
617 sig_tmp_space,
618 ECRYPTFS_SIG_SIZE,
619 &tag_11_contents_size,
620 &tag_11_packet_size,
621 max_packet_size);
622 if (rc) {
623 ecryptfs_printk(KERN_ERR, "No valid "
624 "(ecryptfs-specific) literal "
625 "packet containing "
626 "authentication token "
627 "signature found after "
628 "tag 3 packet\n");
629 rc = -EIO;
630 goto out_wipe_list;
631 }
632 i += tag_11_packet_size;
633 if (ECRYPTFS_SIG_SIZE != tag_11_contents_size) {
634 ecryptfs_printk(KERN_ERR, "Expected "
635 "signature of size [%d]; "
636 "read size [%d]\n",
637 ECRYPTFS_SIG_SIZE,
638 tag_11_contents_size);
639 rc = -EIO;
640 goto out_wipe_list;
641 }
642 ecryptfs_to_hex(new_auth_tok->token.password.signature,
643 sig_tmp_space, tag_11_contents_size);
644 new_auth_tok->token.password.signature[
645 ECRYPTFS_PASSWORD_SIG_SIZE] = '\0';
646 ECRYPTFS_SET_FLAG(crypt_stat->flags,
647 ECRYPTFS_ENCRYPTED);
648 break;
649 case ECRYPTFS_TAG_11_PACKET_TYPE:
650 ecryptfs_printk(KERN_WARNING, "Invalid packet set "
651 "(Tag 11 not allowed by itself)\n");
652 rc = -EIO;
653 goto out_wipe_list;
654 break;
655 default:
656 ecryptfs_printk(KERN_DEBUG, "No packet at offset "
657 "[%d] of the file header; hex value of "
658 "character is [0x%.2x]\n", i, src[i]);
659 next_packet_is_auth_tok_packet = 0;
660 }
661 }
662 if (list_empty(&auth_tok_list)) {
663 rc = -EINVAL; /* Do not support non-encrypted files in
664 * the 0.1 release */
665 goto out;
666 }
667 /* If we have a global auth tok, then we should try to use
668 * it */
669 if (mount_crypt_stat->global_auth_tok) {
670 memcpy(sig, mount_crypt_stat->global_auth_tok_sig,
671 ECRYPTFS_SIG_SIZE_HEX);
672 chosen_auth_tok = mount_crypt_stat->global_auth_tok;
673 } else
674 BUG(); /* We should always have a global auth tok in
675 * the 0.1 release */
676 /* Scan list to see if our chosen_auth_tok works */
677 list_for_each(walker, &auth_tok_list) {
678 struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
679 auth_tok_list_item =
680 list_entry(walker, struct ecryptfs_auth_tok_list_item,
681 list);
682 candidate_auth_tok = &auth_tok_list_item->auth_tok;
683 if (unlikely(ecryptfs_verbosity > 0)) {
684 ecryptfs_printk(KERN_DEBUG,
685 "Considering cadidate auth tok:\n");
686 ecryptfs_dump_auth_tok(candidate_auth_tok);
687 }
688 /* TODO: Replace ECRYPTFS_SIG_SIZE_HEX w/ dynamic value */
689 if (candidate_auth_tok->token_type == ECRYPTFS_PASSWORD
690 && !strncmp(candidate_auth_tok->token.password.signature,
691 sig, ECRYPTFS_SIG_SIZE_HEX)) {
692 found_auth_tok = 1;
693 goto leave_list;
694 /* TODO: Transfer the common salt into the
695 * crypt_stat salt */
696 }
697 }
698leave_list:
699 if (!found_auth_tok) {
700 ecryptfs_printk(KERN_ERR, "Could not find authentication "
701 "token on temporary list for sig [%.*s]\n",
702 ECRYPTFS_SIG_SIZE_HEX, sig);
703 rc = -EIO;
704 goto out_wipe_list;
705 } else {
706 memcpy(&(candidate_auth_tok->token.password),
707 &(chosen_auth_tok->token.password),
708 sizeof(struct ecryptfs_password));
709 rc = decrypt_session_key(candidate_auth_tok, crypt_stat);
710 if (rc) {
711 ecryptfs_printk(KERN_ERR, "Error decrypting the "
712 "session key\n");
713 goto out_wipe_list;
714 }
715 rc = ecryptfs_compute_root_iv(crypt_stat);
716 if (rc) {
717 ecryptfs_printk(KERN_ERR, "Error computing "
718 "the root IV\n");
719 goto out_wipe_list;
720 }
721 }
722 rc = ecryptfs_init_crypt_ctx(crypt_stat);
723 if (rc) {
724 ecryptfs_printk(KERN_ERR, "Error initializing crypto "
725 "context for cipher [%s]; rc = [%d]\n",
726 crypt_stat->cipher, rc);
727 }
728out_wipe_list:
729 wipe_auth_tok_list(&auth_tok_list);
730out:
731 return rc;
732}
733
734/**
735 * write_tag_11_packet
736 * @dest: Target into which Tag 11 packet is to be written
737 * @max: Maximum packet length
738 * @contents: Byte array of contents to copy in
739 * @contents_length: Number of bytes in contents
740 * @packet_length: Length of the Tag 11 packet written; zero on error
741 *
742 * Returns zero on success; non-zero on error.
743 */
744static int
745write_tag_11_packet(char *dest, int max, char *contents, size_t contents_length,
746 size_t *packet_length)
747{
748 int rc = 0;
749 size_t packet_size_length;
750
751 (*packet_length) = 0;
752 if ((13 + contents_length) > max) {
753 rc = -EINVAL;
754 ecryptfs_printk(KERN_ERR, "Packet length larger than "
755 "maximum allowable\n");
756 goto out;
757 }
758 /* General packet header */
759 /* Packet tag */
760 dest[(*packet_length)++] = ECRYPTFS_TAG_11_PACKET_TYPE;
761 /* Packet length */
762 rc = write_packet_length(&dest[(*packet_length)],
763 (13 + contents_length), &packet_size_length);
764 if (rc) {
765 ecryptfs_printk(KERN_ERR, "Error generating tag 11 packet "
766 "header; cannot generate packet length\n");
767 goto out;
768 }
769 (*packet_length) += packet_size_length;
770 /* Tag 11 specific */
771 /* One-octet field that describes how the data is formatted */
772 dest[(*packet_length)++] = 0x62; /* binary data */
773 /* One-octet filename length followed by filename */
774 dest[(*packet_length)++] = 8;
775 memcpy(&dest[(*packet_length)], "_CONSOLE", 8);
776 (*packet_length) += 8;
777 /* Four-octet number indicating modification date */
778 memset(&dest[(*packet_length)], 0x00, 4);
779 (*packet_length) += 4;
780 /* Remainder is literal data */
781 memcpy(&dest[(*packet_length)], contents, contents_length);
782 (*packet_length) += contents_length;
783 out:
784 if (rc)
785 (*packet_length) = 0;
786 return rc;
787}
788
789/**
790 * write_tag_3_packet
791 * @dest: Buffer into which to write the packet
792 * @max: Maximum number of bytes that can be written
793 * @auth_tok: Authentication token
794 * @crypt_stat: The cryptographic context
795 * @key_rec: encrypted key
796 * @packet_size: This function will write the number of bytes that end
797 * up constituting the packet; set to zero on error
798 *
799 * Returns zero on success; non-zero on error.
800 */
801static int
802write_tag_3_packet(char *dest, size_t max, struct ecryptfs_auth_tok *auth_tok,
803 struct ecryptfs_crypt_stat *crypt_stat,
804 struct ecryptfs_key_record *key_rec, size_t *packet_size)
805{
806 int rc = 0;
807
808 size_t i;
809 size_t signature_is_valid = 0;
810 size_t encrypted_session_key_valid = 0;
811 char session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES];
812 struct scatterlist dest_sg[2];
813 struct scatterlist src_sg[2];
814 struct crypto_tfm *tfm = NULL;
815 struct mutex *tfm_mutex = NULL;
816 size_t key_rec_size;
817 size_t packet_size_length;
818 size_t cipher_code;
819
820 (*packet_size) = 0;
821 /* Check for a valid signature on the auth_tok */
822 for (i = 0; i < ECRYPTFS_SIG_SIZE_HEX; i++)
823 signature_is_valid |= auth_tok->token.password.signature[i];
824 if (!signature_is_valid)
825 BUG();
826 ecryptfs_from_hex((*key_rec).sig, auth_tok->token.password.signature,
827 ECRYPTFS_SIG_SIZE);
828 encrypted_session_key_valid = 0;
829 for (i = 0; i < crypt_stat->key_size; i++)
830 encrypted_session_key_valid |=
831 auth_tok->session_key.encrypted_key[i];
832 if (encrypted_session_key_valid) {
833 memcpy((*key_rec).enc_key,
834 auth_tok->session_key.encrypted_key,
835 auth_tok->session_key.encrypted_key_size);
836 goto encrypted_session_key_set;
837 }
838 if (auth_tok->session_key.encrypted_key_size == 0)
839 auth_tok->session_key.encrypted_key_size =
840 crypt_stat->key_size;
841 if (crypt_stat->key_size == 24
842 && strcmp("aes", crypt_stat->cipher) == 0) {
843 memset((crypt_stat->key + 24), 0, 8);
844 auth_tok->session_key.encrypted_key_size = 32;
845 }
846 (*key_rec).enc_key_size =
847 auth_tok->session_key.encrypted_key_size;
848 if (ECRYPTFS_CHECK_FLAG(auth_tok->token.password.flags,
849 ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET)) {
850 ecryptfs_printk(KERN_DEBUG, "Using previously generated "
851 "session key encryption key of size [%d]\n",
852 auth_tok->token.password.
853 session_key_encryption_key_bytes);
854 memcpy(session_key_encryption_key,
855 auth_tok->token.password.session_key_encryption_key,
856 crypt_stat->key_size);
857 ecryptfs_printk(KERN_DEBUG,
858 "Cached session key " "encryption key: \n");
859 if (ecryptfs_verbosity > 0)
860 ecryptfs_dump_hex(session_key_encryption_key, 16);
861 }
862 if (unlikely(ecryptfs_verbosity > 0)) {
863 ecryptfs_printk(KERN_DEBUG, "Session key encryption key:\n");
864 ecryptfs_dump_hex(session_key_encryption_key, 16);
865 }
866 rc = virt_to_scatterlist(crypt_stat->key,
867 (*key_rec).enc_key_size, src_sg, 2);
868 if (!rc) {
869 ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
870 "for crypt_stat session key\n");
871 rc = -ENOMEM;
872 goto out;
873 }
874 rc = virt_to_scatterlist((*key_rec).enc_key,
875 (*key_rec).enc_key_size, dest_sg, 2);
876 if (!rc) {
877 ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
878 "for crypt_stat encrypted session key\n");
879 rc = -ENOMEM;
880 goto out;
881 }
882 if (!strcmp(crypt_stat->cipher,
883 crypt_stat->mount_crypt_stat->global_default_cipher_name)
884 && crypt_stat->mount_crypt_stat->global_key_tfm) {
885 tfm = crypt_stat->mount_crypt_stat->global_key_tfm;
886 tfm_mutex = &crypt_stat->mount_crypt_stat->global_key_tfm_mutex;
887 } else
888 tfm = crypto_alloc_tfm(crypt_stat->cipher, 0);
889 if (!tfm) {
890 ecryptfs_printk(KERN_ERR, "Could not initialize crypto "
891 "context for cipher [%s]\n",
892 crypt_stat->cipher);
893 rc = -EINVAL;
894 goto out;
895 }
896 if (tfm_mutex)
897 mutex_lock(tfm_mutex);
898 rc = crypto_cipher_setkey(tfm, session_key_encryption_key,
899 crypt_stat->key_size);
900 if (rc < 0) {
901 if (tfm_mutex)
902 mutex_unlock(tfm_mutex);
903 ecryptfs_printk(KERN_ERR, "Error setting key for crypto "
904 "context\n");
905 goto out;
906 }
907 rc = 0;
908 ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes of the key\n",
909 crypt_stat->key_size);
910 crypto_cipher_encrypt(tfm, dest_sg, src_sg,
911 (*key_rec).enc_key_size);
912 if (tfm_mutex)
913 mutex_unlock(tfm_mutex);
914 ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n");
915 if (ecryptfs_verbosity > 0)
916 ecryptfs_dump_hex((*key_rec).enc_key,
917 (*key_rec).enc_key_size);
918encrypted_session_key_set:
919 /* Now we have a valid key_rec. Append it to the
920 * key_rec set. */
921 key_rec_size = (sizeof(struct ecryptfs_key_record)
922 - ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES
923 + ((*key_rec).enc_key_size));
924 /* TODO: Include a packet size limit as a parameter to this
925 * function once we have multi-packet headers (for versions
926 * later than 0.1 */
927 if (key_rec_size >= ECRYPTFS_MAX_KEYSET_SIZE) {
928 ecryptfs_printk(KERN_ERR, "Keyset too large\n");
929 rc = -EINVAL;
930 goto out;
931 }
932 /* TODO: Packet size limit */
933 /* We have 5 bytes of surrounding packet data */
934 if ((0x05 + ECRYPTFS_SALT_SIZE
935 + (*key_rec).enc_key_size) >= max) {
936 ecryptfs_printk(KERN_ERR, "Authentication token is too "
937 "large\n");
938 rc = -EINVAL;
939 goto out;
940 }
941 /* This format is inspired by OpenPGP; see RFC 2440
942 * packet tag 3 */
943 dest[(*packet_size)++] = ECRYPTFS_TAG_3_PACKET_TYPE;
944 /* ver+cipher+s2k+hash+salt+iter+enc_key */
945 rc = write_packet_length(&dest[(*packet_size)],
946 (0x05 + ECRYPTFS_SALT_SIZE
947 + (*key_rec).enc_key_size),
948 &packet_size_length);
949 if (rc) {
950 ecryptfs_printk(KERN_ERR, "Error generating tag 3 packet "
951 "header; cannot generate packet length\n");
952 goto out;
953 }
954 (*packet_size) += packet_size_length;
955 dest[(*packet_size)++] = 0x04; /* version 4 */
956 cipher_code = ecryptfs_code_for_cipher_string(crypt_stat);
957 if (cipher_code == 0) {
958 ecryptfs_printk(KERN_WARNING, "Unable to generate code for "
959 "cipher [%s]\n", crypt_stat->cipher);
960 rc = -EINVAL;
961 goto out;
962 }
963 dest[(*packet_size)++] = cipher_code;
964 dest[(*packet_size)++] = 0x03; /* S2K */
965 dest[(*packet_size)++] = 0x01; /* MD5 (TODO: parameterize) */
966 memcpy(&dest[(*packet_size)], auth_tok->token.password.salt,
967 ECRYPTFS_SALT_SIZE);
968 (*packet_size) += ECRYPTFS_SALT_SIZE; /* salt */
969 dest[(*packet_size)++] = 0x60; /* hash iterations (65536) */
970 memcpy(&dest[(*packet_size)], (*key_rec).enc_key,
971 (*key_rec).enc_key_size);
972 (*packet_size) += (*key_rec).enc_key_size;
973out:
974 if (tfm && !tfm_mutex)
975 crypto_free_tfm(tfm);
976 if (rc)
977 (*packet_size) = 0;
978 return rc;
979}
980
981/**
982 * ecryptfs_generate_key_packet_set
983 * @dest: Virtual address from which to write the key record set
984 * @crypt_stat: The cryptographic context from which the
985 * authentication tokens will be retrieved
986 * @ecryptfs_dentry: The dentry, used to retrieve the mount crypt stat
987 * for the global parameters
988 * @len: The amount written
989 * @max: The maximum amount of data allowed to be written
990 *
991 * Generates a key packet set and writes it to the virtual address
992 * passed in.
993 *
994 * Returns zero on success; non-zero on error.
995 */
996int
997ecryptfs_generate_key_packet_set(char *dest_base,
998 struct ecryptfs_crypt_stat *crypt_stat,
999 struct dentry *ecryptfs_dentry, size_t *len,
1000 size_t max)
1001{
1002 int rc = 0;
1003 struct ecryptfs_auth_tok *auth_tok;
1004 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1005 &ecryptfs_superblock_to_private(
1006 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1007 size_t written;
1008 struct ecryptfs_key_record key_rec;
1009
1010 (*len) = 0;
1011 if (mount_crypt_stat->global_auth_tok) {
1012 auth_tok = mount_crypt_stat->global_auth_tok;
1013 if (auth_tok->token_type == ECRYPTFS_PASSWORD) {
1014 rc = write_tag_3_packet((dest_base + (*len)),
1015 max, auth_tok,
1016 crypt_stat, &key_rec,
1017 &written);
1018 if (rc) {
1019 ecryptfs_printk(KERN_WARNING, "Error "
1020 "writing tag 3 packet\n");
1021 goto out;
1022 }
1023 (*len) += written;
1024 /* Write auth tok signature packet */
1025 rc = write_tag_11_packet(
1026 (dest_base + (*len)),
1027 (max - (*len)),
1028 key_rec.sig, ECRYPTFS_SIG_SIZE, &written);
1029 if (rc) {
1030 ecryptfs_printk(KERN_ERR, "Error writing "
1031 "auth tok signature packet\n");
1032 goto out;
1033 }
1034 (*len) += written;
1035 } else {
1036 ecryptfs_printk(KERN_WARNING, "Unsupported "
1037 "authentication token type\n");
1038 rc = -EINVAL;
1039 goto out;
1040 }
1041 if (rc) {
1042 ecryptfs_printk(KERN_WARNING, "Error writing "
1043 "authentication token packet with sig "
1044 "= [%s]\n",
1045 mount_crypt_stat->global_auth_tok_sig);
1046 rc = -EIO;
1047 goto out;
1048 }
1049 } else
1050 BUG();
1051 if (likely((max - (*len)) > 0)) {
1052 dest_base[(*len)] = 0x00;
1053 } else {
1054 ecryptfs_printk(KERN_ERR, "Error writing boundary byte\n");
1055 rc = -EIO;
1056 }
1057out:
1058 if (rc)
1059 (*len) = 0;
1060 return rc;
1061}
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-24 21:33:12 -0500