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uml: speed up page table walking
[pv_ops_mirror.git] / fs / ecryptfs / keystore.c
blobb550dea8eee6bf8828e6383633c37685e4c3b950
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 * Trevor S. Highland <trevor.highland@gmail.com>
11 *
12 * This program is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU General Public License as
14 * published by the Free Software Foundation; either version 2 of the
15 * License, or (at your option) any later version.
16 *
17 * This program is distributed in the hope that it will be useful, but
18 * WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 * General Public License for more details.
21 *
22 * You should have received a copy of the GNU General Public License
23 * along with this program; if not, write to the Free Software
24 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
25 * 02111-1307, USA.
26 */
27
28 #include <linux/string.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 */
42 int 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
67 /**
68 * parse_packet_length
69 * @data: Pointer to memory containing length at offset
70 * @size: This function writes the decoded size to this memory
71 * address; zero on error
72 * @length_size: The number of bytes occupied by the encoded length
73 *
74 * Returns Zero on success
75 */
76 static int parse_packet_length(unsigned char *data, size_t *size,
77 size_t *length_size)
78 {
79 int rc = 0;
80
81 (*length_size) = 0;
82 (*size) = 0;
83 if (data[0] < 192) {
84 /* One-byte length */
85 (*size) = (unsigned char)data[0];
86 (*length_size) = 1;
87 } else if (data[0] < 224) {
88 /* Two-byte length */
89 (*size) = (((unsigned char)(data[0]) - 192) * 256);
90 (*size) += ((unsigned char)(data[1]) + 192);
91 (*length_size) = 2;
92 } else if (data[0] == 255) {
93 /* Five-byte length; we're not supposed to see this */
94 ecryptfs_printk(KERN_ERR, "Five-byte packet length not "
95 "supported\n");
96 rc = -EINVAL;
97 goto out;
98 } else {
99 ecryptfs_printk(KERN_ERR, "Error parsing packet length\n");
100 rc = -EINVAL;
101 goto out;
102 }
103 out:
104 return rc;
105 }
106
107 /**
108 * write_packet_length
109 * @dest: The byte array target into which to write the
110 * length. Must have at least 5 bytes allocated.
111 * @size: The length to write.
112 * @packet_size_length: The number of bytes used to encode the
113 * packet length is written to this address.
114 *
115 * Returns zero on success; non-zero on error.
116 */
117 static int write_packet_length(char *dest, size_t size,
118 size_t *packet_size_length)
119 {
120 int rc = 0;
121
122 if (size < 192) {
123 dest[0] = size;
124 (*packet_size_length) = 1;
125 } else if (size < 65536) {
126 dest[0] = (((size - 192) / 256) + 192);
127 dest[1] = ((size - 192) % 256);
128 (*packet_size_length) = 2;
129 } else {
130 rc = -EINVAL;
131 ecryptfs_printk(KERN_WARNING,
132 "Unsupported packet size: [%d]\n", size);
133 }
134 return rc;
135 }
136
137 static int
138 write_tag_64_packet(char *signature, struct ecryptfs_session_key *session_key,
139 char **packet, size_t *packet_len)
140 {
141 size_t i = 0;
142 size_t data_len;
143 size_t packet_size_len;
144 char *message;
145 int rc;
146
147 /*
148 * ***** TAG 64 Packet Format *****
149 * | Content Type | 1 byte |
150 * | Key Identifier Size | 1 or 2 bytes |
151 * | Key Identifier | arbitrary |
152 * | Encrypted File Encryption Key Size | 1 or 2 bytes |
153 * | Encrypted File Encryption Key | arbitrary |
154 */
155 data_len = (5 + ECRYPTFS_SIG_SIZE_HEX
156 + session_key->encrypted_key_size);
157 *packet = kmalloc(data_len, GFP_KERNEL);
158 message = *packet;
159 if (!message) {
160 ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
161 rc = -ENOMEM;
162 goto out;
163 }
164 message[i++] = ECRYPTFS_TAG_64_PACKET_TYPE;
165 rc = write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
166 &packet_size_len);
167 if (rc) {
168 ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
169 "header; cannot generate packet length\n");
170 goto out;
171 }
172 i += packet_size_len;
173 memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
174 i += ECRYPTFS_SIG_SIZE_HEX;
175 rc = write_packet_length(&message[i], session_key->encrypted_key_size,
176 &packet_size_len);
177 if (rc) {
178 ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
179 "header; cannot generate packet length\n");
180 goto out;
181 }
182 i += packet_size_len;
183 memcpy(&message[i], session_key->encrypted_key,
184 session_key->encrypted_key_size);
185 i += session_key->encrypted_key_size;
186 *packet_len = i;
187 out:
188 return rc;
189 }
190
191 static int
192 parse_tag_65_packet(struct ecryptfs_session_key *session_key, u16 *cipher_code,
193 struct ecryptfs_message *msg)
194 {
195 size_t i = 0;
196 char *data;
197 size_t data_len;
198 size_t m_size;
199 size_t message_len;
200 u16 checksum = 0;
201 u16 expected_checksum = 0;
202 int rc;
203
204 /*
205 * ***** TAG 65 Packet Format *****
206 * | Content Type | 1 byte |
207 * | Status Indicator | 1 byte |
208 * | File Encryption Key Size | 1 or 2 bytes |
209 * | File Encryption Key | arbitrary |
210 */
211 message_len = msg->data_len;
212 data = msg->data;
213 if (message_len < 4) {
214 rc = -EIO;
215 goto out;
216 }
217 if (data[i++] != ECRYPTFS_TAG_65_PACKET_TYPE) {
218 ecryptfs_printk(KERN_ERR, "Type should be ECRYPTFS_TAG_65\n");
219 rc = -EIO;
220 goto out;
221 }
222 if (data[i++]) {
223 ecryptfs_printk(KERN_ERR, "Status indicator has non-zero value "
224 "[%d]\n", data[i-1]);
225 rc = -EIO;
226 goto out;
227 }
228 rc = parse_packet_length(&data[i], &m_size, &data_len);
229 if (rc) {
230 ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
231 "rc = [%d]\n", rc);
232 goto out;
233 }
234 i += data_len;
235 if (message_len < (i + m_size)) {
236 ecryptfs_printk(KERN_ERR, "The received netlink message is "
237 "shorter than expected\n");
238 rc = -EIO;
239 goto out;
240 }
241 if (m_size < 3) {
242 ecryptfs_printk(KERN_ERR,
243 "The decrypted key is not long enough to "
244 "include a cipher code and checksum\n");
245 rc = -EIO;
246 goto out;
247 }
248 *cipher_code = data[i++];
249 /* The decrypted key includes 1 byte cipher code and 2 byte checksum */
250 session_key->decrypted_key_size = m_size - 3;
251 if (session_key->decrypted_key_size > ECRYPTFS_MAX_KEY_BYTES) {
252 ecryptfs_printk(KERN_ERR, "key_size [%d] larger than "
253 "the maximum key size [%d]\n",
254 session_key->decrypted_key_size,
255 ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
256 rc = -EIO;
257 goto out;
258 }
259 memcpy(session_key->decrypted_key, &data[i],
260 session_key->decrypted_key_size);
261 i += session_key->decrypted_key_size;
262 expected_checksum += (unsigned char)(data[i++]) << 8;
263 expected_checksum += (unsigned char)(data[i++]);
264 for (i = 0; i < session_key->decrypted_key_size; i++)
265 checksum += session_key->decrypted_key[i];
266 if (expected_checksum != checksum) {
267 ecryptfs_printk(KERN_ERR, "Invalid checksum for file "
268 "encryption key; expected [%x]; calculated "
269 "[%x]\n", expected_checksum, checksum);
270 rc = -EIO;
271 }
272 out:
273 return rc;
274 }
275
276
277 static int
278 write_tag_66_packet(char *signature, size_t cipher_code,
279 struct ecryptfs_crypt_stat *crypt_stat, char **packet,
280 size_t *packet_len)
281 {
282 size_t i = 0;
283 size_t j;
284 size_t data_len;
285 size_t checksum = 0;
286 size_t packet_size_len;
287 char *message;
288 int rc;
289
290 /*
291 * ***** TAG 66 Packet Format *****
292 * | Content Type | 1 byte |
293 * | Key Identifier Size | 1 or 2 bytes |
294 * | Key Identifier | arbitrary |
295 * | File Encryption Key Size | 1 or 2 bytes |
296 * | File Encryption Key | arbitrary |
297 */
298 data_len = (5 + ECRYPTFS_SIG_SIZE_HEX + crypt_stat->key_size);
299 *packet = kmalloc(data_len, GFP_KERNEL);
300 message = *packet;
301 if (!message) {
302 ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
303 rc = -ENOMEM;
304 goto out;
305 }
306 message[i++] = ECRYPTFS_TAG_66_PACKET_TYPE;
307 rc = write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
308 &packet_size_len);
309 if (rc) {
310 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
311 "header; cannot generate packet length\n");
312 goto out;
313 }
314 i += packet_size_len;
315 memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
316 i += ECRYPTFS_SIG_SIZE_HEX;
317 /* The encrypted key includes 1 byte cipher code and 2 byte checksum */
318 rc = write_packet_length(&message[i], crypt_stat->key_size + 3,
319 &packet_size_len);
320 if (rc) {
321 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
322 "header; cannot generate packet length\n");
323 goto out;
324 }
325 i += packet_size_len;
326 message[i++] = cipher_code;
327 memcpy(&message[i], crypt_stat->key, crypt_stat->key_size);
328 i += crypt_stat->key_size;
329 for (j = 0; j < crypt_stat->key_size; j++)
330 checksum += crypt_stat->key[j];
331 message[i++] = (checksum / 256) % 256;
332 message[i++] = (checksum % 256);
333 *packet_len = i;
334 out:
335 return rc;
336 }
337
338 static int
339 parse_tag_67_packet(struct ecryptfs_key_record *key_rec,
340 struct ecryptfs_message *msg)
341 {
342 size_t i = 0;
343 char *data;
344 size_t data_len;
345 size_t message_len;
346 int rc;
347
348 /*
349 * ***** TAG 65 Packet Format *****
350 * | Content Type | 1 byte |
351 * | Status Indicator | 1 byte |
352 * | Encrypted File Encryption Key Size | 1 or 2 bytes |
353 * | Encrypted File Encryption Key | arbitrary |
354 */
355 message_len = msg->data_len;
356 data = msg->data;
357 /* verify that everything through the encrypted FEK size is present */
358 if (message_len < 4) {
359 rc = -EIO;
360 goto out;
361 }
362 if (data[i++] != ECRYPTFS_TAG_67_PACKET_TYPE) {
363 ecryptfs_printk(KERN_ERR, "Type should be ECRYPTFS_TAG_67\n");
364 rc = -EIO;
365 goto out;
366 }
367 if (data[i++]) {
368 ecryptfs_printk(KERN_ERR, "Status indicator has non zero value"
369 " [%d]\n", data[i-1]);
370 rc = -EIO;
371 goto out;
372 }
373 rc = parse_packet_length(&data[i], &key_rec->enc_key_size, &data_len);
374 if (rc) {
375 ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
376 "rc = [%d]\n", rc);
377 goto out;
378 }
379 i += data_len;
380 if (message_len < (i + key_rec->enc_key_size)) {
381 ecryptfs_printk(KERN_ERR, "message_len [%d]; max len is [%d]\n",
382 message_len, (i + key_rec->enc_key_size));
383 rc = -EIO;
384 goto out;
385 }
386 if (key_rec->enc_key_size > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
387 ecryptfs_printk(KERN_ERR, "Encrypted key_size [%d] larger than "
388 "the maximum key size [%d]\n",
389 key_rec->enc_key_size,
390 ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
391 rc = -EIO;
392 goto out;
393 }
394 memcpy(key_rec->enc_key, &data[i], key_rec->enc_key_size);
395 out:
396 return rc;
397 }
398
399 /**
400 * decrypt_pki_encrypted_session_key - Decrypt the session key with
401 * the given auth_tok.
402 *
403 * Returns Zero on success; non-zero error otherwise.
404 */
405 static int decrypt_pki_encrypted_session_key(
406 struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
407 struct ecryptfs_auth_tok *auth_tok,
408 struct ecryptfs_crypt_stat *crypt_stat)
409 {
410 u16 cipher_code = 0;
411 struct ecryptfs_msg_ctx *msg_ctx;
412 struct ecryptfs_message *msg = NULL;
413 char *netlink_message;
414 size_t netlink_message_length;
415 int rc;
416
417 rc = write_tag_64_packet(mount_crypt_stat->global_auth_tok_sig,
418 &(auth_tok->session_key),
419 &netlink_message, &netlink_message_length);
420 if (rc) {
421 ecryptfs_printk(KERN_ERR, "Failed to write tag 64 packet");
422 goto out;
423 }
424 rc = ecryptfs_send_message(ecryptfs_transport, netlink_message,
425 netlink_message_length, &msg_ctx);
426 if (rc) {
427 ecryptfs_printk(KERN_ERR, "Error sending netlink message\n");
428 goto out;
429 }
430 rc = ecryptfs_wait_for_response(msg_ctx, &msg);
431 if (rc) {
432 ecryptfs_printk(KERN_ERR, "Failed to receive tag 65 packet "
433 "from the user space daemon\n");
434 rc = -EIO;
435 goto out;
436 }
437 rc = parse_tag_65_packet(&(auth_tok->session_key),
438 &cipher_code, msg);
439 if (rc) {
440 printk(KERN_ERR "Failed to parse tag 65 packet; rc = [%d]\n",
441 rc);
442 goto out;
443 }
444 auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
445 memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
446 auth_tok->session_key.decrypted_key_size);
447 crypt_stat->key_size = auth_tok->session_key.decrypted_key_size;
448 rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher, cipher_code);
449 if (rc) {
450 ecryptfs_printk(KERN_ERR, "Cipher code [%d] is invalid\n",
451 cipher_code)
452 goto out;
453 }
454 crypt_stat->flags |= ECRYPTFS_KEY_VALID;
455 if (ecryptfs_verbosity > 0) {
456 ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n");
457 ecryptfs_dump_hex(crypt_stat->key,
458 crypt_stat->key_size);
459 }
460 out:
461 if (msg)
462 kfree(msg);
463 return rc;
464 }
465
466 static void wipe_auth_tok_list(struct list_head *auth_tok_list_head)
467 {
468 struct list_head *walker;
469 struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
470
471 walker = auth_tok_list_head->next;
472 while (walker != auth_tok_list_head) {
473 auth_tok_list_item =
474 list_entry(walker, struct ecryptfs_auth_tok_list_item,
475 list);
476 walker = auth_tok_list_item->list.next;
477 memset(auth_tok_list_item, 0,
478 sizeof(struct ecryptfs_auth_tok_list_item));
479 kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
480 auth_tok_list_item);
481 }
482 auth_tok_list_head->next = NULL;
483 }
484
485 struct kmem_cache *ecryptfs_auth_tok_list_item_cache;
486
487
488 /**
489 * parse_tag_1_packet
490 * @crypt_stat: The cryptographic context to modify based on packet
491 * contents.
492 * @data: The raw bytes of the packet.
493 * @auth_tok_list: eCryptfs parses packets into authentication tokens;
494 * a new authentication token will be placed at the end
495 * of this list for this packet.
496 * @new_auth_tok: Pointer to a pointer to memory that this function
497 * allocates; sets the memory address of the pointer to
498 * NULL on error. This object is added to the
499 * auth_tok_list.
500 * @packet_size: This function writes the size of the parsed packet
501 * into this memory location; zero on error.
502 *
503 * Returns zero on success; non-zero on error.
504 */
505 static int
506 parse_tag_1_packet(struct ecryptfs_crypt_stat *crypt_stat,
507 unsigned char *data, struct list_head *auth_tok_list,
508 struct ecryptfs_auth_tok **new_auth_tok,
509 size_t *packet_size, size_t max_packet_size)
510 {
511 size_t body_size;
512 struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
513 size_t length_size;
514 int rc = 0;
515
516 (*packet_size) = 0;
517 (*new_auth_tok) = NULL;
518
519 /* we check that:
520 * one byte for the Tag 1 ID flag
521 * two bytes for the body size
522 * do not exceed the maximum_packet_size
523 */
524 if (unlikely((*packet_size) + 3 > max_packet_size)) {
525 ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
526 rc = -EINVAL;
527 goto out;
528 }
529 /* check for Tag 1 identifier - one byte */
530 if (data[(*packet_size)++] != ECRYPTFS_TAG_1_PACKET_TYPE) {
531 ecryptfs_printk(KERN_ERR, "Enter w/ first byte != 0x%.2x\n",
532 ECRYPTFS_TAG_1_PACKET_TYPE);
533 rc = -EINVAL;
534 goto out;
535 }
536 /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
537 * at end of function upon failure */
538 auth_tok_list_item =
539 kmem_cache_alloc(ecryptfs_auth_tok_list_item_cache,
540 GFP_KERNEL);
541 if (!auth_tok_list_item) {
542 ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
543 rc = -ENOMEM;
544 goto out;
545 }
546 memset(auth_tok_list_item, 0,
547 sizeof(struct ecryptfs_auth_tok_list_item));
548 (*new_auth_tok) = &auth_tok_list_item->auth_tok;
549 /* check for body size - one to two bytes
550 *
551 * ***** TAG 1 Packet Format *****
552 * | version number | 1 byte |
553 * | key ID | 8 bytes |
554 * | public key algorithm | 1 byte |
555 * | encrypted session key | arbitrary |
556 */
557 rc = parse_packet_length(&data[(*packet_size)], &body_size,
558 &length_size);
559 if (rc) {
560 ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
561 "rc = [%d]\n", rc);
562 goto out_free;
563 }
564 if (unlikely(body_size < (0x02 + ECRYPTFS_SIG_SIZE))) {
565 ecryptfs_printk(KERN_WARNING, "Invalid body size ([%d])\n",
566 body_size);
567 rc = -EINVAL;
568 goto out_free;
569 }
570 (*packet_size) += length_size;
571 if (unlikely((*packet_size) + body_size > max_packet_size)) {
572 ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
573 rc = -EINVAL;
574 goto out_free;
575 }
576 /* Version 3 (from RFC2440) - one byte */
577 if (unlikely(data[(*packet_size)++] != 0x03)) {
578 ecryptfs_printk(KERN_DEBUG, "Unknown version number "
579 "[%d]\n", data[(*packet_size) - 1]);
580 rc = -EINVAL;
581 goto out_free;
582 }
583 /* Read Signature */
584 ecryptfs_to_hex((*new_auth_tok)->token.private_key.signature,
585 &data[(*packet_size)], ECRYPTFS_SIG_SIZE);
586 *packet_size += ECRYPTFS_SIG_SIZE;
587 /* This byte is skipped because the kernel does not need to
588 * know which public key encryption algorithm was used */
589 (*packet_size)++;
590 (*new_auth_tok)->session_key.encrypted_key_size =
591 body_size - (0x02 + ECRYPTFS_SIG_SIZE);
592 if ((*new_auth_tok)->session_key.encrypted_key_size
593 > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
594 ecryptfs_printk(KERN_ERR, "Tag 1 packet contains key larger "
595 "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES");
596 rc = -EINVAL;
597 goto out;
598 }
599 ecryptfs_printk(KERN_DEBUG, "Encrypted key size = [%d]\n",
600 (*new_auth_tok)->session_key.encrypted_key_size);
601 memcpy((*new_auth_tok)->session_key.encrypted_key,
602 &data[(*packet_size)], (body_size - 0x02 - ECRYPTFS_SIG_SIZE));
603 (*packet_size) += (*new_auth_tok)->session_key.encrypted_key_size;
604 (*new_auth_tok)->session_key.flags &=
605 ~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
606 (*new_auth_tok)->session_key.flags |=
607 ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
608 (*new_auth_tok)->token_type = ECRYPTFS_PRIVATE_KEY;
609 (*new_auth_tok)->flags |= ECRYPTFS_PRIVATE_KEY;
610 /* TODO: Why are we setting this flag here? Don't we want the
611 * userspace to decrypt the session key? */
612 (*new_auth_tok)->session_key.flags &=
613 ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
614 (*new_auth_tok)->session_key.flags &=
615 ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
616 list_add(&auth_tok_list_item->list, auth_tok_list);
617 goto out;
618 out_free:
619 (*new_auth_tok) = NULL;
620 memset(auth_tok_list_item, 0,
621 sizeof(struct ecryptfs_auth_tok_list_item));
622 kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
623 auth_tok_list_item);
624 out:
625 if (rc)
626 (*packet_size) = 0;
627 return rc;
628 }
629
630 /**
631 * parse_tag_3_packet
632 * @crypt_stat: The cryptographic context to modify based on packet
633 * contents.
634 * @data: The raw bytes of the packet.
635 * @auth_tok_list: eCryptfs parses packets into authentication tokens;
636 * a new authentication token will be placed at the end
637 * of this list for this packet.
638 * @new_auth_tok: Pointer to a pointer to memory that this function
639 * allocates; sets the memory address of the pointer to
640 * NULL on error. This object is added to the
641 * auth_tok_list.
642 * @packet_size: This function writes the size of the parsed packet
643 * into this memory location; zero on error.
644 * @max_packet_size: maximum number of bytes to parse
645 *
646 * Returns zero on success; non-zero on error.
647 */
648 static int
649 parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat,
650 unsigned char *data, struct list_head *auth_tok_list,
651 struct ecryptfs_auth_tok **new_auth_tok,
652 size_t *packet_size, size_t max_packet_size)
653 {
654 size_t body_size;
655 struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
656 size_t length_size;
657 int rc = 0;
658
659 (*packet_size) = 0;
660 (*new_auth_tok) = NULL;
661
662 /* we check that:
663 * one byte for the Tag 3 ID flag
664 * two bytes for the body size
665 * do not exceed the maximum_packet_size
666 */
667 if (unlikely((*packet_size) + 3 > max_packet_size)) {
668 ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
669 rc = -EINVAL;
670 goto out;
671 }
672
673 /* check for Tag 3 identifyer - one byte */
674 if (data[(*packet_size)++] != ECRYPTFS_TAG_3_PACKET_TYPE) {
675 ecryptfs_printk(KERN_ERR, "Enter w/ first byte != 0x%.2x\n",
676 ECRYPTFS_TAG_3_PACKET_TYPE);
677 rc = -EINVAL;
678 goto out;
679 }
680 /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
681 * at end of function upon failure */
682 auth_tok_list_item =
683 kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache, GFP_KERNEL);
684 if (!auth_tok_list_item) {
685 ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
686 rc = -ENOMEM;
687 goto out;
688 }
689 (*new_auth_tok) = &auth_tok_list_item->auth_tok;
690
691 /* check for body size - one to two bytes */
692 rc = parse_packet_length(&data[(*packet_size)], &body_size,
693 &length_size);
694 if (rc) {
695 ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
696 "rc = [%d]\n", rc);
697 goto out_free;
698 }
699 if (unlikely(body_size < (0x05 + ECRYPTFS_SALT_SIZE))) {
700 ecryptfs_printk(KERN_WARNING, "Invalid body size ([%d])\n",
701 body_size);
702 rc = -EINVAL;
703 goto out_free;
704 }
705 (*packet_size) += length_size;
706
707 /* now we know the length of the remainting Tag 3 packet size:
708 * 5 fix bytes for: version string, cipher, S2K ID, hash algo,
709 * number of hash iterations
710 * ECRYPTFS_SALT_SIZE bytes for salt
711 * body_size bytes minus the stuff above is the encrypted key size
712 */
713 if (unlikely((*packet_size) + body_size > max_packet_size)) {
714 ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
715 rc = -EINVAL;
716 goto out_free;
717 }
718
719 /* There are 5 characters of additional information in the
720 * packet */
721 (*new_auth_tok)->session_key.encrypted_key_size =
722 body_size - (0x05 + ECRYPTFS_SALT_SIZE);
723 ecryptfs_printk(KERN_DEBUG, "Encrypted key size = [%d]\n",
724 (*new_auth_tok)->session_key.encrypted_key_size);
725
726 /* Version 4 (from RFC2440) - one byte */
727 if (unlikely(data[(*packet_size)++] != 0x04)) {
728 ecryptfs_printk(KERN_DEBUG, "Unknown version number "
729 "[%d]\n", data[(*packet_size) - 1]);
730 rc = -EINVAL;
731 goto out_free;
732 }
733
734 /* cipher - one byte */
735 ecryptfs_cipher_code_to_string(crypt_stat->cipher,
736 (u16)data[(*packet_size)]);
737 /* A little extra work to differentiate among the AES key
738 * sizes; see RFC2440 */
739 switch(data[(*packet_size)++]) {
740 case RFC2440_CIPHER_AES_192:
741 crypt_stat->key_size = 24;
742 break;
743 default:
744 crypt_stat->key_size =
745 (*new_auth_tok)->session_key.encrypted_key_size;
746 }
747 ecryptfs_init_crypt_ctx(crypt_stat);
748 /* S2K identifier 3 (from RFC2440) */
749 if (unlikely(data[(*packet_size)++] != 0x03)) {
750 ecryptfs_printk(KERN_ERR, "Only S2K ID 3 is currently "
751 "supported\n");
752 rc = -ENOSYS;
753 goto out_free;
754 }
755
756 /* TODO: finish the hash mapping */
757 /* hash algorithm - one byte */
758 switch (data[(*packet_size)++]) {
759 case 0x01: /* See RFC2440 for these numbers and their mappings */
760 /* Choose MD5 */
761 /* salt - ECRYPTFS_SALT_SIZE bytes */
762 memcpy((*new_auth_tok)->token.password.salt,
763 &data[(*packet_size)], ECRYPTFS_SALT_SIZE);
764 (*packet_size) += ECRYPTFS_SALT_SIZE;
765
766 /* This conversion was taken straight from RFC2440 */
767 /* number of hash iterations - one byte */
768 (*new_auth_tok)->token.password.hash_iterations =
769 ((u32) 16 + (data[(*packet_size)] & 15))
770 << ((data[(*packet_size)] >> 4) + 6);
771 (*packet_size)++;
772
773 /* encrypted session key -
774 * (body_size-5-ECRYPTFS_SALT_SIZE) bytes */
775 memcpy((*new_auth_tok)->session_key.encrypted_key,
776 &data[(*packet_size)],
777 (*new_auth_tok)->session_key.encrypted_key_size);
778 (*packet_size) +=
779 (*new_auth_tok)->session_key.encrypted_key_size;
780 (*new_auth_tok)->session_key.flags &=
781 ~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
782 (*new_auth_tok)->session_key.flags |=
783 ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
784 (*new_auth_tok)->token.password.hash_algo = 0x01;
785 break;
786 default:
787 ecryptfs_printk(KERN_ERR, "Unsupported hash algorithm: "
788 "[%d]\n", data[(*packet_size) - 1]);
789 rc = -ENOSYS;
790 goto out_free;
791 }
792 (*new_auth_tok)->token_type = ECRYPTFS_PASSWORD;
793 /* TODO: Parametarize; we might actually want userspace to
794 * decrypt the session key. */
795 (*new_auth_tok)->session_key.flags &=
796 ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
797 (*new_auth_tok)->session_key.flags &=
798 ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
799 list_add(&auth_tok_list_item->list, auth_tok_list);
800 goto out;
801 out_free:
802 (*new_auth_tok) = NULL;
803 memset(auth_tok_list_item, 0,
804 sizeof(struct ecryptfs_auth_tok_list_item));
805 kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
806 auth_tok_list_item);
807 out:
808 if (rc)
809 (*packet_size) = 0;
810 return rc;
811 }
812
813 /**
814 * parse_tag_11_packet
815 * @data: The raw bytes of the packet
816 * @contents: This function writes the data contents of the literal
817 * packet into this memory location
818 * @max_contents_bytes: The maximum number of bytes that this function
819 * is allowed to write into contents
820 * @tag_11_contents_size: This function writes the size of the parsed
821 * contents into this memory location; zero on
822 * error
823 * @packet_size: This function writes the size of the parsed packet
824 * into this memory location; zero on error
825 * @max_packet_size: maximum number of bytes to parse
826 *
827 * Returns zero on success; non-zero on error.
828 */
829 static int
830 parse_tag_11_packet(unsigned char *data, unsigned char *contents,
831 size_t max_contents_bytes, size_t *tag_11_contents_size,
832 size_t *packet_size, size_t max_packet_size)
833 {
834 size_t body_size;
835 size_t length_size;
836 int rc = 0;
837
838 (*packet_size) = 0;
839 (*tag_11_contents_size) = 0;
840
841 /* check that:
842 * one byte for the Tag 11 ID flag
843 * two bytes for the Tag 11 length
844 * do not exceed the maximum_packet_size
845 */
846 if (unlikely((*packet_size) + 3 > max_packet_size)) {
847 ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
848 rc = -EINVAL;
849 goto out;
850 }
851
852 /* check for Tag 11 identifyer - one byte */
853 if (data[(*packet_size)++] != ECRYPTFS_TAG_11_PACKET_TYPE) {
854 ecryptfs_printk(KERN_WARNING,
855 "Invalid tag 11 packet format\n");
856 rc = -EINVAL;
857 goto out;
858 }
859
860 /* get Tag 11 content length - one or two bytes */
861 rc = parse_packet_length(&data[(*packet_size)], &body_size,
862 &length_size);
863 if (rc) {
864 ecryptfs_printk(KERN_WARNING,
865 "Invalid tag 11 packet format\n");
866 goto out;
867 }
868 (*packet_size) += length_size;
869
870 if (body_size < 13) {
871 ecryptfs_printk(KERN_WARNING, "Invalid body size ([%d])\n",
872 body_size);
873 rc = -EINVAL;
874 goto out;
875 }
876 /* We have 13 bytes of surrounding packet values */
877 (*tag_11_contents_size) = (body_size - 13);
878
879 /* now we know the length of the remainting Tag 11 packet size:
880 * 14 fix bytes for: special flag one, special flag two,
881 * 12 skipped bytes
882 * body_size bytes minus the stuff above is the Tag 11 content
883 */
884 /* FIXME why is the body size one byte smaller than the actual
885 * size of the body?
886 * this seems to be an error here as well as in
887 * write_tag_11_packet() */
888 if (unlikely((*packet_size) + body_size + 1 > max_packet_size)) {
889 ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
890 rc = -EINVAL;
891 goto out;
892 }
893
894 /* special flag one - one byte */
895 if (data[(*packet_size)++] != 0x62) {
896 ecryptfs_printk(KERN_WARNING, "Unrecognizable packet\n");
897 rc = -EINVAL;
898 goto out;
899 }
900
901 /* special flag two - one byte */
902 if (data[(*packet_size)++] != 0x08) {
903 ecryptfs_printk(KERN_WARNING, "Unrecognizable packet\n");
904 rc = -EINVAL;
905 goto out;
906 }
907
908 /* skip the next 12 bytes */
909 (*packet_size) += 12; /* We don't care about the filename or
910 * the timestamp */
911
912 /* get the Tag 11 contents - tag_11_contents_size bytes */
913 memcpy(contents, &data[(*packet_size)], (*tag_11_contents_size));
914 (*packet_size) += (*tag_11_contents_size);
915
916 out:
917 if (rc) {
918 (*packet_size) = 0;
919 (*tag_11_contents_size) = 0;
920 }
921 return rc;
922 }
923
924 /**
925 * decrypt_session_key - Decrypt the session key with the given auth_tok.
926 *
927 * Returns Zero on success; non-zero error otherwise.
928 */
929 static int decrypt_session_key(struct ecryptfs_auth_tok *auth_tok,
930 struct ecryptfs_crypt_stat *crypt_stat)
931 {
932 struct ecryptfs_password *password_s_ptr;
933 struct scatterlist src_sg[2], dst_sg[2];
934 struct mutex *tfm_mutex = NULL;
935 char *encrypted_session_key;
936 char *session_key;
937 struct blkcipher_desc desc = {
938 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
939 };
940 int rc = 0;
941
942 password_s_ptr = &auth_tok->token.password;
943 if (password_s_ptr->flags & ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET)
944 ecryptfs_printk(KERN_DEBUG, "Session key encryption key "
945 "set; skipping key generation\n");
946 ecryptfs_printk(KERN_DEBUG, "Session key encryption key (size [%d])"
947 ":\n",
948 password_s_ptr->session_key_encryption_key_bytes);
949 if (ecryptfs_verbosity > 0)
950 ecryptfs_dump_hex(password_s_ptr->session_key_encryption_key,
951 password_s_ptr->
952 session_key_encryption_key_bytes);
953 if (!strcmp(crypt_stat->cipher,
954 crypt_stat->mount_crypt_stat->global_default_cipher_name)
955 && crypt_stat->mount_crypt_stat->global_key_tfm) {
956 desc.tfm = crypt_stat->mount_crypt_stat->global_key_tfm;
957 tfm_mutex = &crypt_stat->mount_crypt_stat->global_key_tfm_mutex;
958 } else {
959 char *full_alg_name;
960
961 rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
962 crypt_stat->cipher,
963 "ecb");
964 if (rc)
965 goto out;
966 desc.tfm = crypto_alloc_blkcipher(full_alg_name, 0,
967 CRYPTO_ALG_ASYNC);
968 kfree(full_alg_name);
969 if (IS_ERR(desc.tfm)) {
970 rc = PTR_ERR(desc.tfm);
971 printk(KERN_ERR "Error allocating crypto context; "
972 "rc = [%d]\n", rc);
973 goto out;
974 }
975 crypto_blkcipher_set_flags(desc.tfm, CRYPTO_TFM_REQ_WEAK_KEY);
976 }
977 if (tfm_mutex)
978 mutex_lock(tfm_mutex);
979 rc = crypto_blkcipher_setkey(desc.tfm,
980 password_s_ptr->session_key_encryption_key,
981 crypt_stat->key_size);
982 if (rc < 0) {
983 printk(KERN_ERR "Error setting key for crypto context\n");
984 rc = -EINVAL;
985 goto out_free_tfm;
986 }
987 /* TODO: virt_to_scatterlist */
988 encrypted_session_key = (char *)__get_free_page(GFP_KERNEL);
989 if (!encrypted_session_key) {
990 ecryptfs_printk(KERN_ERR, "Out of memory\n");
991 rc = -ENOMEM;
992 goto out_free_tfm;
993 }
994 session_key = (char *)__get_free_page(GFP_KERNEL);
995 if (!session_key) {
996 kfree(encrypted_session_key);
997 ecryptfs_printk(KERN_ERR, "Out of memory\n");
998 rc = -ENOMEM;
999 goto out_free_tfm;
1000 }
1001 memcpy(encrypted_session_key, auth_tok->session_key.encrypted_key,
1002 auth_tok->session_key.encrypted_key_size);
1003 src_sg[0].page = virt_to_page(encrypted_session_key);
1004 src_sg[0].offset = 0;
1005 BUG_ON(auth_tok->session_key.encrypted_key_size > PAGE_CACHE_SIZE);
1006 src_sg[0].length = auth_tok->session_key.encrypted_key_size;
1007 dst_sg[0].page = virt_to_page(session_key);
1008 dst_sg[0].offset = 0;
1009 auth_tok->session_key.decrypted_key_size =
1010 auth_tok->session_key.encrypted_key_size;
1011 dst_sg[0].length = auth_tok->session_key.encrypted_key_size;
1012 rc = crypto_blkcipher_decrypt(&desc, dst_sg, src_sg,
1013 auth_tok->session_key.encrypted_key_size);
1014 if (rc) {
1015 printk(KERN_ERR "Error decrypting; rc = [%d]\n", rc);
1016 goto out_free_memory;
1017 }
1018 auth_tok->session_key.decrypted_key_size =
1019 auth_tok->session_key.encrypted_key_size;
1020 memcpy(auth_tok->session_key.decrypted_key, session_key,
1021 auth_tok->session_key.decrypted_key_size);
1022 auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1023 memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
1024 auth_tok->session_key.decrypted_key_size);
1025 crypt_stat->flags |= ECRYPTFS_KEY_VALID;
1026 ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n");
1027 if (ecryptfs_verbosity > 0)
1028 ecryptfs_dump_hex(crypt_stat->key,
1029 crypt_stat->key_size);
1030 out_free_memory:
1031 memset(encrypted_session_key, 0, PAGE_CACHE_SIZE);
1032 free_page((unsigned long)encrypted_session_key);
1033 memset(session_key, 0, PAGE_CACHE_SIZE);
1034 free_page((unsigned long)session_key);
1035 out_free_tfm:
1036 if (tfm_mutex)
1037 mutex_unlock(tfm_mutex);
1038 else
1039 crypto_free_blkcipher(desc.tfm);
1040 out:
1041 return rc;
1042 }
1043
1044 /**
1045 * ecryptfs_parse_packet_set
1046 * @dest: The header page in memory
1047 * @version: Version of file format, to guide parsing behavior
1048 *
1049 * Get crypt_stat to have the file's session key if the requisite key
1050 * is available to decrypt the session key.
1051 *
1052 * Returns Zero if a valid authentication token was retrieved and
1053 * processed; negative value for file not encrypted or for error
1054 * conditions.
1055 */
1056 int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
1057 unsigned char *src,
1058 struct dentry *ecryptfs_dentry)
1059 {
1060 size_t i = 0;
1061 size_t found_auth_tok = 0;
1062 size_t next_packet_is_auth_tok_packet;
1063 char sig[ECRYPTFS_SIG_SIZE_HEX];
1064 struct list_head auth_tok_list;
1065 struct list_head *walker;
1066 struct ecryptfs_auth_tok *chosen_auth_tok = NULL;
1067 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1068 &ecryptfs_superblock_to_private(
1069 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1070 struct ecryptfs_auth_tok *candidate_auth_tok = NULL;
1071 size_t packet_size;
1072 struct ecryptfs_auth_tok *new_auth_tok;
1073 unsigned char sig_tmp_space[ECRYPTFS_SIG_SIZE];
1074 size_t tag_11_contents_size;
1075 size_t tag_11_packet_size;
1076 int rc = 0;
1077
1078 INIT_LIST_HEAD(&auth_tok_list);
1079 /* Parse the header to find as many packets as we can, these will be
1080 * added the our &auth_tok_list */
1081 next_packet_is_auth_tok_packet = 1;
1082 while (next_packet_is_auth_tok_packet) {
1083 size_t max_packet_size = ((PAGE_CACHE_SIZE - 8) - i);
1084
1085 switch (src[i]) {
1086 case ECRYPTFS_TAG_3_PACKET_TYPE:
1087 rc = parse_tag_3_packet(crypt_stat,
1088 (unsigned char *)&src[i],
1089 &auth_tok_list, &new_auth_tok,
1090 &packet_size, max_packet_size);
1091 if (rc) {
1092 ecryptfs_printk(KERN_ERR, "Error parsing "
1093 "tag 3 packet\n");
1094 rc = -EIO;
1095 goto out_wipe_list;
1096 }
1097 i += packet_size;
1098 rc = parse_tag_11_packet((unsigned char *)&src[i],
1099 sig_tmp_space,
1100 ECRYPTFS_SIG_SIZE,
1101 &tag_11_contents_size,
1102 &tag_11_packet_size,
1103 max_packet_size);
1104 if (rc) {
1105 ecryptfs_printk(KERN_ERR, "No valid "
1106 "(ecryptfs-specific) literal "
1107 "packet containing "
1108 "authentication token "
1109 "signature found after "
1110 "tag 3 packet\n");
1111 rc = -EIO;
1112 goto out_wipe_list;
1113 }
1114 i += tag_11_packet_size;
1115 if (ECRYPTFS_SIG_SIZE != tag_11_contents_size) {
1116 ecryptfs_printk(KERN_ERR, "Expected "
1117 "signature of size [%d]; "
1118 "read size [%d]\n",
1119 ECRYPTFS_SIG_SIZE,
1120 tag_11_contents_size);
1121 rc = -EIO;
1122 goto out_wipe_list;
1123 }
1124 ecryptfs_to_hex(new_auth_tok->token.password.signature,
1125 sig_tmp_space, tag_11_contents_size);
1126 new_auth_tok->token.password.signature[
1127 ECRYPTFS_PASSWORD_SIG_SIZE] = '\0';
1128 crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
1129 break;
1130 case ECRYPTFS_TAG_1_PACKET_TYPE:
1131 rc = parse_tag_1_packet(crypt_stat,
1132 (unsigned char *)&src[i],
1133 &auth_tok_list, &new_auth_tok,
1134 &packet_size, max_packet_size);
1135 if (rc) {
1136 ecryptfs_printk(KERN_ERR, "Error parsing "
1137 "tag 1 packet\n");
1138 rc = -EIO;
1139 goto out_wipe_list;
1140 }
1141 i += packet_size;
1142 crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
1143 break;
1144 case ECRYPTFS_TAG_11_PACKET_TYPE:
1145 ecryptfs_printk(KERN_WARNING, "Invalid packet set "
1146 "(Tag 11 not allowed by itself)\n");
1147 rc = -EIO;
1148 goto out_wipe_list;
1149 break;
1150 default:
1151 ecryptfs_printk(KERN_DEBUG, "No packet at offset "
1152 "[%d] of the file header; hex value of "
1153 "character is [0x%.2x]\n", i, src[i]);
1154 next_packet_is_auth_tok_packet = 0;
1155 }
1156 }
1157 if (list_empty(&auth_tok_list)) {
1158 rc = -EINVAL; /* Do not support non-encrypted files in
1159 * the 0.1 release */
1160 goto out;
1161 }
1162 /* If we have a global auth tok, then we should try to use
1163 * it */
1164 if (mount_crypt_stat->global_auth_tok) {
1165 memcpy(sig, mount_crypt_stat->global_auth_tok_sig,
1166 ECRYPTFS_SIG_SIZE_HEX);
1167 chosen_auth_tok = mount_crypt_stat->global_auth_tok;
1168 } else
1169 BUG(); /* We should always have a global auth tok in
1170 * the 0.1 release */
1171 /* Scan list to see if our chosen_auth_tok works */
1172 list_for_each(walker, &auth_tok_list) {
1173 struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1174 auth_tok_list_item =
1175 list_entry(walker, struct ecryptfs_auth_tok_list_item,
1176 list);
1177 candidate_auth_tok = &auth_tok_list_item->auth_tok;
1178 if (unlikely(ecryptfs_verbosity > 0)) {
1179 ecryptfs_printk(KERN_DEBUG,
1180 "Considering cadidate auth tok:\n");
1181 ecryptfs_dump_auth_tok(candidate_auth_tok);
1182 }
1183 /* TODO: Replace ECRYPTFS_SIG_SIZE_HEX w/ dynamic value */
1184 if (candidate_auth_tok->token_type == ECRYPTFS_PASSWORD
1185 && !strncmp(candidate_auth_tok->token.password.signature,
1186 sig, ECRYPTFS_SIG_SIZE_HEX)) {
1187 found_auth_tok = 1;
1188 goto leave_list;
1189 /* TODO: Transfer the common salt into the
1190 * crypt_stat salt */
1191 } else if ((candidate_auth_tok->token_type
1192 == ECRYPTFS_PRIVATE_KEY)
1193 && !strncmp(candidate_auth_tok->token.private_key.signature,
1194 sig, ECRYPTFS_SIG_SIZE_HEX)) {
1195 found_auth_tok = 1;
1196 goto leave_list;
1197 }
1198 }
1199 if (!found_auth_tok) {
1200 ecryptfs_printk(KERN_ERR, "Could not find authentication "
1201 "token on temporary list for sig [%.*s]\n",
1202 ECRYPTFS_SIG_SIZE_HEX, sig);
1203 rc = -EIO;
1204 goto out_wipe_list;
1205 }
1206 leave_list:
1207 rc = -ENOTSUPP;
1208 if (candidate_auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
1209 memcpy(&(candidate_auth_tok->token.private_key),
1210 &(chosen_auth_tok->token.private_key),
1211 sizeof(struct ecryptfs_private_key));
1212 rc = decrypt_pki_encrypted_session_key(mount_crypt_stat,
1213 candidate_auth_tok,
1214 crypt_stat);
1215 } else if (candidate_auth_tok->token_type == ECRYPTFS_PASSWORD) {
1216 memcpy(&(candidate_auth_tok->token.password),
1217 &(chosen_auth_tok->token.password),
1218 sizeof(struct ecryptfs_password));
1219 rc = decrypt_session_key(candidate_auth_tok, crypt_stat);
1220 }
1221 if (rc) {
1222 ecryptfs_printk(KERN_ERR, "Error decrypting the "
1223 "session key; rc = [%d]\n", rc);
1224 goto out_wipe_list;
1225 }
1226 rc = ecryptfs_compute_root_iv(crypt_stat);
1227 if (rc) {
1228 ecryptfs_printk(KERN_ERR, "Error computing "
1229 "the root IV\n");
1230 goto out_wipe_list;
1231 }
1232 rc = ecryptfs_init_crypt_ctx(crypt_stat);
1233 if (rc) {
1234 ecryptfs_printk(KERN_ERR, "Error initializing crypto "
1235 "context for cipher [%s]; rc = [%d]\n",
1236 crypt_stat->cipher, rc);
1237 }
1238 out_wipe_list:
1239 wipe_auth_tok_list(&auth_tok_list);
1240 out:
1241 return rc;
1242 }
1243 static int
1244 pki_encrypt_session_key(struct ecryptfs_auth_tok *auth_tok,
1245 struct ecryptfs_crypt_stat *crypt_stat,
1246 struct ecryptfs_key_record *key_rec)
1247 {
1248 struct ecryptfs_msg_ctx *msg_ctx = NULL;
1249 char *netlink_payload;
1250 size_t netlink_payload_length;
1251 struct ecryptfs_message *msg;
1252 int rc;
1253
1254 rc = write_tag_66_packet(auth_tok->token.private_key.signature,
1255 ecryptfs_code_for_cipher_string(crypt_stat),
1256 crypt_stat, &netlink_payload,
1257 &netlink_payload_length);
1258 if (rc) {
1259 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet\n");
1260 goto out;
1261 }
1262 rc = ecryptfs_send_message(ecryptfs_transport, netlink_payload,
1263 netlink_payload_length, &msg_ctx);
1264 if (rc) {
1265 ecryptfs_printk(KERN_ERR, "Error sending netlink message\n");
1266 goto out;
1267 }
1268 rc = ecryptfs_wait_for_response(msg_ctx, &msg);
1269 if (rc) {
1270 ecryptfs_printk(KERN_ERR, "Failed to receive tag 67 packet "
1271 "from the user space daemon\n");
1272 rc = -EIO;
1273 goto out;
1274 }
1275 rc = parse_tag_67_packet(key_rec, msg);
1276 if (rc)
1277 ecryptfs_printk(KERN_ERR, "Error parsing tag 67 packet\n");
1278 kfree(msg);
1279 out:
1280 if (netlink_payload)
1281 kfree(netlink_payload);
1282 return rc;
1283 }
1284 /**
1285 * write_tag_1_packet - Write an RFC2440-compatible tag 1 (public key) packet
1286 * @dest: Buffer into which to write the packet
1287 * @max: Maximum number of bytes that can be writtn
1288 * @packet_size: This function will write the number of bytes that end
1289 * up constituting the packet; set to zero on error
1290 *
1291 * Returns zero on success; non-zero on error.
1292 */
1293 static int
1294 write_tag_1_packet(char *dest, size_t max, struct ecryptfs_auth_tok *auth_tok,
1295 struct ecryptfs_crypt_stat *crypt_stat,
1296 struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
1297 struct ecryptfs_key_record *key_rec, size_t *packet_size)
1298 {
1299 size_t i;
1300 size_t encrypted_session_key_valid = 0;
1301 size_t key_rec_size;
1302 size_t packet_size_length;
1303 int rc = 0;
1304
1305 (*packet_size) = 0;
1306 ecryptfs_from_hex(key_rec->sig, auth_tok->token.private_key.signature,
1307 ECRYPTFS_SIG_SIZE);
1308 encrypted_session_key_valid = 0;
1309 for (i = 0; i < crypt_stat->key_size; i++)
1310 encrypted_session_key_valid |=
1311 auth_tok->session_key.encrypted_key[i];
1312 if (encrypted_session_key_valid) {
1313 memcpy(key_rec->enc_key,
1314 auth_tok->session_key.encrypted_key,
1315 auth_tok->session_key.encrypted_key_size);
1316 goto encrypted_session_key_set;
1317 }
1318 if (auth_tok->session_key.encrypted_key_size == 0)
1319 auth_tok->session_key.encrypted_key_size =
1320 auth_tok->token.private_key.key_size;
1321 rc = pki_encrypt_session_key(auth_tok, crypt_stat, key_rec);
1322 if (rc) {
1323 ecryptfs_printk(KERN_ERR, "Failed to encrypt session key "
1324 "via a pki");
1325 goto out;
1326 }
1327 if (ecryptfs_verbosity > 0) {
1328 ecryptfs_printk(KERN_DEBUG, "Encrypted key:\n");
1329 ecryptfs_dump_hex(key_rec->enc_key, key_rec->enc_key_size);
1330 }
1331 encrypted_session_key_set:
1332 /* Now we have a valid key_rec. Append it to the
1333 * key_rec set. */
1334 key_rec_size = (sizeof(struct ecryptfs_key_record)
1335 - ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES
1336 + (key_rec->enc_key_size));
1337 /* TODO: Include a packet size limit as a parameter to this
1338 * function once we have multi-packet headers (for versions
1339 * later than 0.1 */
1340 if (key_rec_size >= ECRYPTFS_MAX_KEYSET_SIZE) {
1341 ecryptfs_printk(KERN_ERR, "Keyset too large\n");
1342 rc = -EINVAL;
1343 goto out;
1344 }
1345 /* ***** TAG 1 Packet Format *****
1346 * | version number | 1 byte |
1347 * | key ID | 8 bytes |
1348 * | public key algorithm | 1 byte |
1349 * | encrypted session key | arbitrary |
1350 */
1351 if ((0x02 + ECRYPTFS_SIG_SIZE + key_rec->enc_key_size) >= max) {
1352 ecryptfs_printk(KERN_ERR,
1353 "Authentication token is too large\n");
1354 rc = -EINVAL;
1355 goto out;
1356 }
1357 dest[(*packet_size)++] = ECRYPTFS_TAG_1_PACKET_TYPE;
1358 /* This format is inspired by OpenPGP; see RFC 2440
1359 * packet tag 1 */
1360 rc = write_packet_length(&dest[(*packet_size)],
1361 (0x02 + ECRYPTFS_SIG_SIZE +
1362 key_rec->enc_key_size),
1363 &packet_size_length);
1364 if (rc) {
1365 ecryptfs_printk(KERN_ERR, "Error generating tag 1 packet "
1366 "header; cannot generate packet length\n");
1367 goto out;
1368 }
1369 (*packet_size) += packet_size_length;
1370 dest[(*packet_size)++] = 0x03; /* version 3 */
1371 memcpy(&dest[(*packet_size)], key_rec->sig, ECRYPTFS_SIG_SIZE);
1372 (*packet_size) += ECRYPTFS_SIG_SIZE;
1373 dest[(*packet_size)++] = RFC2440_CIPHER_RSA;
1374 memcpy(&dest[(*packet_size)], key_rec->enc_key,
1375 key_rec->enc_key_size);
1376 (*packet_size) += key_rec->enc_key_size;
1377 out:
1378 if (rc)
1379 (*packet_size) = 0;
1380 return rc;
1381 }
1382
1383 /**
1384 * write_tag_11_packet
1385 * @dest: Target into which Tag 11 packet is to be written
1386 * @max: Maximum packet length
1387 * @contents: Byte array of contents to copy in
1388 * @contents_length: Number of bytes in contents
1389 * @packet_length: Length of the Tag 11 packet written; zero on error
1390 *
1391 * Returns zero on success; non-zero on error.
1392 */
1393 static int
1394 write_tag_11_packet(char *dest, int max, char *contents, size_t contents_length,
1395 size_t *packet_length)
1396 {
1397 size_t packet_size_length;
1398 int rc = 0;
1399
1400 (*packet_length) = 0;
1401 if ((13 + contents_length) > max) {
1402 rc = -EINVAL;
1403 ecryptfs_printk(KERN_ERR, "Packet length larger than "
1404 "maximum allowable\n");
1405 goto out;
1406 }
1407 /* General packet header */
1408 /* Packet tag */
1409 dest[(*packet_length)++] = ECRYPTFS_TAG_11_PACKET_TYPE;
1410 /* Packet length */
1411 rc = write_packet_length(&dest[(*packet_length)],
1412 (13 + contents_length), &packet_size_length);
1413 if (rc) {
1414 ecryptfs_printk(KERN_ERR, "Error generating tag 11 packet "
1415 "header; cannot generate packet length\n");
1416 goto out;
1417 }
1418 (*packet_length) += packet_size_length;
1419 /* Tag 11 specific */
1420 /* One-octet field that describes how the data is formatted */
1421 dest[(*packet_length)++] = 0x62; /* binary data */
1422 /* One-octet filename length followed by filename */
1423 dest[(*packet_length)++] = 8;
1424 memcpy(&dest[(*packet_length)], "_CONSOLE", 8);
1425 (*packet_length) += 8;
1426 /* Four-octet number indicating modification date */
1427 memset(&dest[(*packet_length)], 0x00, 4);
1428 (*packet_length) += 4;
1429 /* Remainder is literal data */
1430 memcpy(&dest[(*packet_length)], contents, contents_length);
1431 (*packet_length) += contents_length;
1432 out:
1433 if (rc)
1434 (*packet_length) = 0;
1435 return rc;
1436 }
1437
1438 /**
1439 * write_tag_3_packet
1440 * @dest: Buffer into which to write the packet
1441 * @max: Maximum number of bytes that can be written
1442 * @auth_tok: Authentication token
1443 * @crypt_stat: The cryptographic context
1444 * @key_rec: encrypted key
1445 * @packet_size: This function will write the number of bytes that end
1446 * up constituting the packet; set to zero on error
1447 *
1448 * Returns zero on success; non-zero on error.
1449 */
1450 static int
1451 write_tag_3_packet(char *dest, size_t max, struct ecryptfs_auth_tok *auth_tok,
1452 struct ecryptfs_crypt_stat *crypt_stat,
1453 struct ecryptfs_key_record *key_rec, size_t *packet_size)
1454 {
1455 size_t i;
1456 size_t encrypted_session_key_valid = 0;
1457 char session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES];
1458 struct scatterlist dest_sg[2];
1459 struct scatterlist src_sg[2];
1460 struct mutex *tfm_mutex = NULL;
1461 size_t key_rec_size;
1462 size_t packet_size_length;
1463 size_t cipher_code;
1464 struct blkcipher_desc desc = {
1465 .tfm = NULL,
1466 .flags = CRYPTO_TFM_REQ_MAY_SLEEP
1467 };
1468 int rc = 0;
1469
1470 (*packet_size) = 0;
1471 ecryptfs_from_hex(key_rec->sig, auth_tok->token.password.signature,
1472 ECRYPTFS_SIG_SIZE);
1473 encrypted_session_key_valid = 0;
1474 for (i = 0; i < crypt_stat->key_size; i++)
1475 encrypted_session_key_valid |=
1476 auth_tok->session_key.encrypted_key[i];
1477 if (encrypted_session_key_valid) {
1478 memcpy(key_rec->enc_key,
1479 auth_tok->session_key.encrypted_key,
1480 auth_tok->session_key.encrypted_key_size);
1481 goto encrypted_session_key_set;
1482 }
1483 if (auth_tok->session_key.encrypted_key_size == 0)
1484 auth_tok->session_key.encrypted_key_size =
1485 crypt_stat->key_size;
1486 if (crypt_stat->key_size == 24
1487 && strcmp("aes", crypt_stat->cipher) == 0) {
1488 memset((crypt_stat->key + 24), 0, 8);
1489 auth_tok->session_key.encrypted_key_size = 32;
1490 }
1491 key_rec->enc_key_size =
1492 auth_tok->session_key.encrypted_key_size;
1493 if (auth_tok->token.password.flags &
1494 ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET) {
1495 ecryptfs_printk(KERN_DEBUG, "Using previously generated "
1496 "session key encryption key of size [%d]\n",
1497 auth_tok->token.password.
1498 session_key_encryption_key_bytes);
1499 memcpy(session_key_encryption_key,
1500 auth_tok->token.password.session_key_encryption_key,
1501 crypt_stat->key_size);
1502 ecryptfs_printk(KERN_DEBUG,
1503 "Cached session key " "encryption key: \n");
1504 if (ecryptfs_verbosity > 0)
1505 ecryptfs_dump_hex(session_key_encryption_key, 16);
1506 }
1507 if (unlikely(ecryptfs_verbosity > 0)) {
1508 ecryptfs_printk(KERN_DEBUG, "Session key encryption key:\n");
1509 ecryptfs_dump_hex(session_key_encryption_key, 16);
1510 }
1511 rc = virt_to_scatterlist(crypt_stat->key,
1512 key_rec->enc_key_size, src_sg, 2);
1513 if (!rc) {
1514 ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
1515 "for crypt_stat session key\n");
1516 rc = -ENOMEM;
1517 goto out;
1518 }
1519 rc = virt_to_scatterlist(key_rec->enc_key,
1520 key_rec->enc_key_size, dest_sg, 2);
1521 if (!rc) {
1522 ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
1523 "for crypt_stat encrypted session key\n");
1524 rc = -ENOMEM;
1525 goto out;
1526 }
1527 if (!strcmp(crypt_stat->cipher,
1528 crypt_stat->mount_crypt_stat->global_default_cipher_name)
1529 && crypt_stat->mount_crypt_stat->global_key_tfm) {
1530 desc.tfm = crypt_stat->mount_crypt_stat->global_key_tfm;
1531 tfm_mutex = &crypt_stat->mount_crypt_stat->global_key_tfm_mutex;
1532 } else {
1533 char *full_alg_name;
1534
1535 rc = ecryptfs_crypto_api_algify_cipher_name(&full_alg_name,
1536 crypt_stat->cipher,
1537 "ecb");
1538 if (rc)
1539 goto out;
1540 desc.tfm = crypto_alloc_blkcipher(full_alg_name, 0,
1541 CRYPTO_ALG_ASYNC);
1542 kfree(full_alg_name);
1543 if (IS_ERR(desc.tfm)) {
1544 rc = PTR_ERR(desc.tfm);
1545 ecryptfs_printk(KERN_ERR, "Could not initialize crypto "
1546 "context for cipher [%s]; rc = [%d]\n",
1547 crypt_stat->cipher, rc);
1548 goto out;
1549 }
1550 crypto_blkcipher_set_flags(desc.tfm, CRYPTO_TFM_REQ_WEAK_KEY);
1551 }
1552 if (tfm_mutex)
1553 mutex_lock(tfm_mutex);
1554 rc = crypto_blkcipher_setkey(desc.tfm, session_key_encryption_key,
1555 crypt_stat->key_size);
1556 if (rc < 0) {
1557 if (tfm_mutex)
1558 mutex_unlock(tfm_mutex);
1559 ecryptfs_printk(KERN_ERR, "Error setting key for crypto "
1560 "context; rc = [%d]\n", rc);
1561 goto out;
1562 }
1563 rc = 0;
1564 ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes of the key\n",
1565 crypt_stat->key_size);
1566 rc = crypto_blkcipher_encrypt(&desc, dest_sg, src_sg,
1567 (*key_rec).enc_key_size);
1568 if (rc) {
1569 printk(KERN_ERR "Error encrypting; rc = [%d]\n", rc);
1570 goto out;
1571 }
1572 if (tfm_mutex)
1573 mutex_unlock(tfm_mutex);
1574 ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n");
1575 if (ecryptfs_verbosity > 0)
1576 ecryptfs_dump_hex(key_rec->enc_key,
1577 key_rec->enc_key_size);
1578 encrypted_session_key_set:
1579 /* Now we have a valid key_rec. Append it to the
1580 * key_rec set. */
1581 key_rec_size = (sizeof(struct ecryptfs_key_record)
1582 - ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES
1583 + (key_rec->enc_key_size));
1584 /* TODO: Include a packet size limit as a parameter to this
1585 * function once we have multi-packet headers (for versions
1586 * later than 0.1 */
1587 if (key_rec_size >= ECRYPTFS_MAX_KEYSET_SIZE) {
1588 ecryptfs_printk(KERN_ERR, "Keyset too large\n");
1589 rc = -EINVAL;
1590 goto out;
1591 }
1592 /* TODO: Packet size limit */
1593 /* We have 5 bytes of surrounding packet data */
1594 if ((0x05 + ECRYPTFS_SALT_SIZE
1595 + key_rec->enc_key_size) >= max) {
1596 ecryptfs_printk(KERN_ERR, "Authentication token is too "
1597 "large\n");
1598 rc = -EINVAL;
1599 goto out;
1600 }
1601 /* This format is inspired by OpenPGP; see RFC 2440
1602 * packet tag 3 */
1603 dest[(*packet_size)++] = ECRYPTFS_TAG_3_PACKET_TYPE;
1604 /* ver+cipher+s2k+hash+salt+iter+enc_key */
1605 rc = write_packet_length(&dest[(*packet_size)],
1606 (0x05 + ECRYPTFS_SALT_SIZE
1607 + key_rec->enc_key_size),
1608 &packet_size_length);
1609 if (rc) {
1610 ecryptfs_printk(KERN_ERR, "Error generating tag 3 packet "
1611 "header; cannot generate packet length\n");
1612 goto out;
1613 }
1614 (*packet_size) += packet_size_length;
1615 dest[(*packet_size)++] = 0x04; /* version 4 */
1616 cipher_code = ecryptfs_code_for_cipher_string(crypt_stat);
1617 if (cipher_code == 0) {
1618 ecryptfs_printk(KERN_WARNING, "Unable to generate code for "
1619 "cipher [%s]\n", crypt_stat->cipher);
1620 rc = -EINVAL;
1621 goto out;
1622 }
1623 dest[(*packet_size)++] = cipher_code;
1624 dest[(*packet_size)++] = 0x03; /* S2K */
1625 dest[(*packet_size)++] = 0x01; /* MD5 (TODO: parameterize) */
1626 memcpy(&dest[(*packet_size)], auth_tok->token.password.salt,
1627 ECRYPTFS_SALT_SIZE);
1628 (*packet_size) += ECRYPTFS_SALT_SIZE; /* salt */
1629 dest[(*packet_size)++] = 0x60; /* hash iterations (65536) */
1630 memcpy(&dest[(*packet_size)], key_rec->enc_key,
1631 key_rec->enc_key_size);
1632 (*packet_size) += key_rec->enc_key_size;
1633 out:
1634 if (desc.tfm && !tfm_mutex)
1635 crypto_free_blkcipher(desc.tfm);
1636 if (rc)
1637 (*packet_size) = 0;
1638 return rc;
1639 }
1640
1641 struct kmem_cache *ecryptfs_key_record_cache;
1642
1643 /**
1644 * ecryptfs_generate_key_packet_set
1645 * @dest: Virtual address from which to write the key record set
1646 * @crypt_stat: The cryptographic context from which the
1647 * authentication tokens will be retrieved
1648 * @ecryptfs_dentry: The dentry, used to retrieve the mount crypt stat
1649 * for the global parameters
1650 * @len: The amount written
1651 * @max: The maximum amount of data allowed to be written
1652 *
1653 * Generates a key packet set and writes it to the virtual address
1654 * passed in.
1655 *
1656 * Returns zero on success; non-zero on error.
1657 */
1658 int
1659 ecryptfs_generate_key_packet_set(char *dest_base,
1660 struct ecryptfs_crypt_stat *crypt_stat,
1661 struct dentry *ecryptfs_dentry, size_t *len,
1662 size_t max)
1663 {
1664 struct ecryptfs_auth_tok *auth_tok;
1665 struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
1666 &ecryptfs_superblock_to_private(
1667 ecryptfs_dentry->d_sb)->mount_crypt_stat;
1668 size_t written;
1669 struct ecryptfs_key_record *key_rec;
1670 int rc = 0;
1671
1672 (*len) = 0;
1673 key_rec = kmem_cache_alloc(ecryptfs_key_record_cache, GFP_KERNEL);
1674 if (!key_rec) {
1675 rc = -ENOMEM;
1676 goto out;
1677 }
1678 if (mount_crypt_stat->global_auth_tok) {
1679 auth_tok = mount_crypt_stat->global_auth_tok;
1680 if (auth_tok->token_type == ECRYPTFS_PASSWORD) {
1681 rc = write_tag_3_packet((dest_base + (*len)),
1682 max, auth_tok,
1683 crypt_stat, key_rec,
1684 &written);
1685 if (rc) {
1686 ecryptfs_printk(KERN_WARNING, "Error "
1687 "writing tag 3 packet\n");
1688 goto out_free;
1689 }
1690 (*len) += written;
1691 /* Write auth tok signature packet */
1692 rc = write_tag_11_packet(
1693 (dest_base + (*len)),
1694 (max - (*len)),
1695 key_rec->sig, ECRYPTFS_SIG_SIZE, &written);
1696 if (rc) {
1697 ecryptfs_printk(KERN_ERR, "Error writing "
1698 "auth tok signature packet\n");
1699 goto out_free;
1700 }
1701 (*len) += written;
1702 } else if (auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
1703 rc = write_tag_1_packet(dest_base + (*len),
1704 max, auth_tok,
1705 crypt_stat,mount_crypt_stat,
1706 key_rec, &written);
1707 if (rc) {
1708 ecryptfs_printk(KERN_WARNING, "Error "
1709 "writing tag 1 packet\n");
1710 goto out_free;
1711 }
1712 (*len) += written;
1713 } else {
1714 ecryptfs_printk(KERN_WARNING, "Unsupported "
1715 "authentication token type\n");
1716 rc = -EINVAL;
1717 goto out_free;
1718 }
1719 } else
1720 BUG();
1721 if (likely((max - (*len)) > 0)) {
1722 dest_base[(*len)] = 0x00;
1723 } else {
1724 ecryptfs_printk(KERN_ERR, "Error writing boundary byte\n");
1725 rc = -EIO;
1726 }
1727
1728 out_free:
1729 kmem_cache_free(ecryptfs_key_record_cache, key_rec);
1730 out:
1731 if (rc)
1732 (*len) = 0;
1733 return rc;
1734 }
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