xref: /linux/fs/ecryptfs/keystore.c (revision 621cde16e49b3ecf7d59a8106a20aaebfb4a59a9)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * eCryptfs: Linux filesystem encryption layer
4  * In-kernel key management code.  Includes functions to parse and
5  * write authentication token-related packets with the underlying
6  * file.
7  *
8  * Copyright (C) 2004-2006 International Business Machines Corp.
9  *   Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
10  *              Michael C. Thompson <mcthomps@us.ibm.com>
11  *              Trevor S. Highland <trevor.highland@gmail.com>
12  */
13 
14 #include <crypto/hash.h>
15 #include <crypto/skcipher.h>
16 #include <linux/string.h>
17 #include <linux/pagemap.h>
18 #include <linux/key.h>
19 #include <linux/random.h>
20 #include <linux/scatterlist.h>
21 #include <linux/slab.h>
22 #include "ecryptfs_kernel.h"
23 
24 /*
25  * request_key returned an error instead of a valid key address;
26  * determine the type of error, make appropriate log entries, and
27  * return an error code.
28  */
process_request_key_err(long err_code)29 static int process_request_key_err(long err_code)
30 {
31 	int rc = 0;
32 
33 	switch (err_code) {
34 	case -ENOKEY:
35 		ecryptfs_printk(KERN_WARNING, "No key\n");
36 		rc = -ENOENT;
37 		break;
38 	case -EKEYEXPIRED:
39 		ecryptfs_printk(KERN_WARNING, "Key expired\n");
40 		rc = -ETIME;
41 		break;
42 	case -EKEYREVOKED:
43 		ecryptfs_printk(KERN_WARNING, "Key revoked\n");
44 		rc = -EINVAL;
45 		break;
46 	default:
47 		ecryptfs_printk(KERN_WARNING, "Unknown error code: "
48 				"[0x%.16lx]\n", err_code);
49 		rc = -EINVAL;
50 	}
51 	return rc;
52 }
53 
process_find_global_auth_tok_for_sig_err(int err_code)54 static int process_find_global_auth_tok_for_sig_err(int err_code)
55 {
56 	int rc = err_code;
57 
58 	switch (err_code) {
59 	case -ENOENT:
60 		ecryptfs_printk(KERN_WARNING, "Missing auth tok\n");
61 		break;
62 	case -EINVAL:
63 		ecryptfs_printk(KERN_WARNING, "Invalid auth tok\n");
64 		break;
65 	default:
66 		rc = process_request_key_err(err_code);
67 		break;
68 	}
69 	return rc;
70 }
71 
72 /**
73  * ecryptfs_parse_packet_length
74  * @data: Pointer to memory containing length at offset
75  * @size: This function writes the decoded size to this memory
76  *        address; zero on error
77  * @length_size: The number of bytes occupied by the encoded length
78  *
79  * Returns zero on success; non-zero on error
80  */
ecryptfs_parse_packet_length(unsigned char * data,size_t * size,size_t * length_size)81 int ecryptfs_parse_packet_length(unsigned char *data, size_t *size,
82 				 size_t *length_size)
83 {
84 	int rc = 0;
85 
86 	(*length_size) = 0;
87 	(*size) = 0;
88 	if (data[0] < 192) {
89 		/* One-byte length */
90 		(*size) = data[0];
91 		(*length_size) = 1;
92 	} else if (data[0] < 224) {
93 		/* Two-byte length */
94 		(*size) = (data[0] - 192) * 256;
95 		(*size) += data[1] + 192;
96 		(*length_size) = 2;
97 	} else if (data[0] == 255) {
98 		/* If support is added, adjust ECRYPTFS_MAX_PKT_LEN_SIZE */
99 		ecryptfs_printk(KERN_ERR, "Five-byte packet length not "
100 				"supported\n");
101 		rc = -EINVAL;
102 		goto out;
103 	} else {
104 		ecryptfs_printk(KERN_ERR, "Error parsing packet length\n");
105 		rc = -EINVAL;
106 		goto out;
107 	}
108 out:
109 	return rc;
110 }
111 
112 /**
113  * ecryptfs_write_packet_length
114  * @dest: The byte array target into which to write the length. Must
115  *        have at least ECRYPTFS_MAX_PKT_LEN_SIZE bytes allocated.
116  * @size: The length to write.
117  * @packet_size_length: The number of bytes used to encode the packet
118  *                      length is written to this address.
119  *
120  * Returns zero on success; non-zero on error.
121  */
ecryptfs_write_packet_length(char * dest,size_t size,size_t * packet_size_length)122 int ecryptfs_write_packet_length(char *dest, size_t size,
123 				 size_t *packet_size_length)
124 {
125 	int rc = 0;
126 
127 	if (size < 192) {
128 		dest[0] = size;
129 		(*packet_size_length) = 1;
130 	} else if (size < 65536) {
131 		dest[0] = (((size - 192) / 256) + 192);
132 		dest[1] = ((size - 192) % 256);
133 		(*packet_size_length) = 2;
134 	} else {
135 		/* If support is added, adjust ECRYPTFS_MAX_PKT_LEN_SIZE */
136 		rc = -EINVAL;
137 		ecryptfs_printk(KERN_WARNING,
138 				"Unsupported packet size: [%zd]\n", size);
139 	}
140 	return rc;
141 }
142 
143 static int
write_tag_64_packet(char * signature,struct ecryptfs_session_key * session_key,char ** packet,size_t * packet_len)144 write_tag_64_packet(char *signature, struct ecryptfs_session_key *session_key,
145 		    char **packet, size_t *packet_len)
146 {
147 	size_t i = 0;
148 	size_t data_len;
149 	size_t packet_size_len;
150 	char *message;
151 	int rc;
152 
153 	/*
154 	 *              ***** TAG 64 Packet Format *****
155 	 *    | Content Type                       | 1 byte       |
156 	 *    | Key Identifier Size                | 1 or 2 bytes |
157 	 *    | Key Identifier                     | arbitrary    |
158 	 *    | Encrypted File Encryption Key Size | 1 or 2 bytes |
159 	 *    | Encrypted File Encryption Key      | arbitrary    |
160 	 */
161 	data_len = (5 + ECRYPTFS_SIG_SIZE_HEX
162 		    + session_key->encrypted_key_size);
163 	*packet = kmalloc(data_len, GFP_KERNEL);
164 	message = *packet;
165 	if (!message) {
166 		ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
167 		rc = -ENOMEM;
168 		goto out;
169 	}
170 	message[i++] = ECRYPTFS_TAG_64_PACKET_TYPE;
171 	rc = ecryptfs_write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
172 					  &packet_size_len);
173 	if (rc) {
174 		ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
175 				"header; cannot generate packet length\n");
176 		goto out;
177 	}
178 	i += packet_size_len;
179 	memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
180 	i += ECRYPTFS_SIG_SIZE_HEX;
181 	rc = ecryptfs_write_packet_length(&message[i],
182 					  session_key->encrypted_key_size,
183 					  &packet_size_len);
184 	if (rc) {
185 		ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
186 				"header; cannot generate packet length\n");
187 		goto out;
188 	}
189 	i += packet_size_len;
190 	memcpy(&message[i], session_key->encrypted_key,
191 	       session_key->encrypted_key_size);
192 	i += session_key->encrypted_key_size;
193 	*packet_len = i;
194 out:
195 	return rc;
196 }
197 
198 static int
parse_tag_65_packet(struct ecryptfs_session_key * session_key,u8 * cipher_code,struct ecryptfs_message * msg)199 parse_tag_65_packet(struct ecryptfs_session_key *session_key, u8 *cipher_code,
200 		    struct ecryptfs_message *msg)
201 {
202 	size_t i = 0;
203 	char *data;
204 	size_t data_len;
205 	size_t m_size;
206 	size_t message_len;
207 	u16 checksum = 0;
208 	u16 expected_checksum = 0;
209 	int rc;
210 
211 	/*
212 	 *              ***** TAG 65 Packet Format *****
213 	 *         | Content Type             | 1 byte       |
214 	 *         | Status Indicator         | 1 byte       |
215 	 *         | File Encryption Key Size | 1 or 2 bytes |
216 	 *         | File Encryption Key      | arbitrary    |
217 	 */
218 	message_len = msg->data_len;
219 	data = msg->data;
220 	if (message_len < 4) {
221 		rc = -EIO;
222 		goto out;
223 	}
224 	if (data[i++] != ECRYPTFS_TAG_65_PACKET_TYPE) {
225 		ecryptfs_printk(KERN_ERR, "Type should be ECRYPTFS_TAG_65\n");
226 		rc = -EIO;
227 		goto out;
228 	}
229 	if (data[i++]) {
230 		ecryptfs_printk(KERN_ERR, "Status indicator has non-zero value "
231 				"[%d]\n", data[i-1]);
232 		rc = -EIO;
233 		goto out;
234 	}
235 	rc = ecryptfs_parse_packet_length(&data[i], &m_size, &data_len);
236 	if (rc) {
237 		ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
238 				"rc = [%d]\n", rc);
239 		goto out;
240 	}
241 	i += data_len;
242 	if (message_len < (i + m_size)) {
243 		ecryptfs_printk(KERN_ERR, "The message received from ecryptfsd "
244 				"is shorter than expected\n");
245 		rc = -EIO;
246 		goto out;
247 	}
248 	if (m_size < 3) {
249 		ecryptfs_printk(KERN_ERR,
250 				"The decrypted key is not long enough to "
251 				"include a cipher code and checksum\n");
252 		rc = -EIO;
253 		goto out;
254 	}
255 	*cipher_code = data[i++];
256 	/* The decrypted key includes 1 byte cipher code and 2 byte checksum */
257 	session_key->decrypted_key_size = m_size - 3;
258 	if (session_key->decrypted_key_size > ECRYPTFS_MAX_KEY_BYTES) {
259 		ecryptfs_printk(KERN_ERR, "key_size [%d] larger than "
260 				"the maximum key size [%d]\n",
261 				session_key->decrypted_key_size,
262 				ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
263 		rc = -EIO;
264 		goto out;
265 	}
266 	memcpy(session_key->decrypted_key, &data[i],
267 	       session_key->decrypted_key_size);
268 	i += session_key->decrypted_key_size;
269 	expected_checksum += (unsigned char)(data[i++]) << 8;
270 	expected_checksum += (unsigned char)(data[i++]);
271 	for (i = 0; i < session_key->decrypted_key_size; i++)
272 		checksum += session_key->decrypted_key[i];
273 	if (expected_checksum != checksum) {
274 		ecryptfs_printk(KERN_ERR, "Invalid checksum for file "
275 				"encryption  key; expected [%x]; calculated "
276 				"[%x]\n", expected_checksum, checksum);
277 		rc = -EIO;
278 	}
279 out:
280 	return rc;
281 }
282 
283 
284 static int
write_tag_66_packet(char * signature,u8 cipher_code,struct ecryptfs_crypt_stat * crypt_stat,char ** packet,size_t * packet_len)285 write_tag_66_packet(char *signature, u8 cipher_code,
286 		    struct ecryptfs_crypt_stat *crypt_stat, char **packet,
287 		    size_t *packet_len)
288 {
289 	size_t i = 0;
290 	size_t j;
291 	size_t data_len;
292 	size_t checksum = 0;
293 	size_t packet_size_len;
294 	char *message;
295 	int rc;
296 
297 	/*
298 	 *              ***** TAG 66 Packet Format *****
299 	 *         | Content Type             | 1 byte       |
300 	 *         | Key Identifier Size      | 1 or 2 bytes |
301 	 *         | Key Identifier           | arbitrary    |
302 	 *         | File Encryption Key Size | 1 or 2 bytes |
303 	 *         | Cipher Code              | 1 byte       |
304 	 *         | File Encryption Key      | arbitrary    |
305 	 *         | Checksum                 | 2 bytes      |
306 	 */
307 	data_len = (8 + ECRYPTFS_SIG_SIZE_HEX + crypt_stat->key_size);
308 	*packet = kmalloc(data_len, GFP_KERNEL);
309 	message = *packet;
310 	if (!message) {
311 		ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
312 		rc = -ENOMEM;
313 		goto out;
314 	}
315 	message[i++] = ECRYPTFS_TAG_66_PACKET_TYPE;
316 	rc = ecryptfs_write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
317 					  &packet_size_len);
318 	if (rc) {
319 		ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
320 				"header; cannot generate packet length\n");
321 		goto out;
322 	}
323 	i += packet_size_len;
324 	memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
325 	i += ECRYPTFS_SIG_SIZE_HEX;
326 	/* The encrypted key includes 1 byte cipher code and 2 byte checksum */
327 	rc = ecryptfs_write_packet_length(&message[i], crypt_stat->key_size + 3,
328 					  &packet_size_len);
329 	if (rc) {
330 		ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
331 				"header; cannot generate packet length\n");
332 		goto out;
333 	}
334 	i += packet_size_len;
335 	message[i++] = cipher_code;
336 	memcpy(&message[i], crypt_stat->key, crypt_stat->key_size);
337 	i += crypt_stat->key_size;
338 	for (j = 0; j < crypt_stat->key_size; j++)
339 		checksum += crypt_stat->key[j];
340 	message[i++] = (checksum / 256) % 256;
341 	message[i++] = (checksum % 256);
342 	*packet_len = i;
343 out:
344 	return rc;
345 }
346 
347 static int
parse_tag_67_packet(struct ecryptfs_key_record * key_rec,struct ecryptfs_message * msg)348 parse_tag_67_packet(struct ecryptfs_key_record *key_rec,
349 		    struct ecryptfs_message *msg)
350 {
351 	size_t i = 0;
352 	char *data;
353 	size_t data_len;
354 	size_t message_len;
355 	int rc;
356 
357 	/*
358 	 *              ***** TAG 65 Packet Format *****
359 	 *    | Content Type                       | 1 byte       |
360 	 *    | Status Indicator                   | 1 byte       |
361 	 *    | Encrypted File Encryption Key Size | 1 or 2 bytes |
362 	 *    | Encrypted File Encryption Key      | arbitrary    |
363 	 */
364 	message_len = msg->data_len;
365 	data = msg->data;
366 	/* verify that everything through the encrypted FEK size is present */
367 	if (message_len < 4) {
368 		rc = -EIO;
369 		printk(KERN_ERR "%s: message_len is [%zd]; minimum acceptable "
370 		       "message length is [%d]\n", __func__, message_len, 4);
371 		goto out;
372 	}
373 	if (data[i++] != ECRYPTFS_TAG_67_PACKET_TYPE) {
374 		rc = -EIO;
375 		printk(KERN_ERR "%s: Type should be ECRYPTFS_TAG_67\n",
376 		       __func__);
377 		goto out;
378 	}
379 	if (data[i++]) {
380 		rc = -EIO;
381 		printk(KERN_ERR "%s: Status indicator has non zero "
382 		       "value [%d]\n", __func__, data[i-1]);
383 
384 		goto out;
385 	}
386 	rc = ecryptfs_parse_packet_length(&data[i], &key_rec->enc_key_size,
387 					  &data_len);
388 	if (rc) {
389 		ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
390 				"rc = [%d]\n", rc);
391 		goto out;
392 	}
393 	i += data_len;
394 	if (message_len < (i + key_rec->enc_key_size)) {
395 		rc = -EIO;
396 		printk(KERN_ERR "%s: message_len [%zd]; max len is [%zd]\n",
397 		       __func__, message_len, (i + key_rec->enc_key_size));
398 		goto out;
399 	}
400 	if (key_rec->enc_key_size > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
401 		rc = -EIO;
402 		printk(KERN_ERR "%s: Encrypted key_size [%zd] larger than "
403 		       "the maximum key size [%d]\n", __func__,
404 		       key_rec->enc_key_size,
405 		       ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
406 		goto out;
407 	}
408 	memcpy(key_rec->enc_key, &data[i], key_rec->enc_key_size);
409 out:
410 	return rc;
411 }
412 
413 /**
414  * ecryptfs_verify_version
415  * @version: The version number to confirm
416  *
417  * Returns zero on good version; non-zero otherwise
418  */
ecryptfs_verify_version(u16 version)419 static int ecryptfs_verify_version(u16 version)
420 {
421 	int rc = 0;
422 	unsigned char major;
423 	unsigned char minor;
424 
425 	major = ((version >> 8) & 0xFF);
426 	minor = (version & 0xFF);
427 	if (major != ECRYPTFS_VERSION_MAJOR) {
428 		ecryptfs_printk(KERN_ERR, "Major version number mismatch. "
429 				"Expected [%d]; got [%d]\n",
430 				ECRYPTFS_VERSION_MAJOR, major);
431 		rc = -EINVAL;
432 		goto out;
433 	}
434 	if (minor != ECRYPTFS_VERSION_MINOR) {
435 		ecryptfs_printk(KERN_ERR, "Minor version number mismatch. "
436 				"Expected [%d]; got [%d]\n",
437 				ECRYPTFS_VERSION_MINOR, minor);
438 		rc = -EINVAL;
439 		goto out;
440 	}
441 out:
442 	return rc;
443 }
444 
445 /**
446  * ecryptfs_verify_auth_tok_from_key
447  * @auth_tok_key: key containing the authentication token
448  * @auth_tok: authentication token
449  *
450  * Returns zero on valid auth tok; -EINVAL if the payload is invalid; or
451  * -EKEYREVOKED if the key was revoked before we acquired its semaphore.
452  */
453 static int
ecryptfs_verify_auth_tok_from_key(struct key * auth_tok_key,struct ecryptfs_auth_tok ** auth_tok)454 ecryptfs_verify_auth_tok_from_key(struct key *auth_tok_key,
455 				  struct ecryptfs_auth_tok **auth_tok)
456 {
457 	int rc = 0;
458 
459 	(*auth_tok) = ecryptfs_get_key_payload_data(auth_tok_key);
460 	if (IS_ERR(*auth_tok)) {
461 		rc = PTR_ERR(*auth_tok);
462 		*auth_tok = NULL;
463 		goto out;
464 	}
465 
466 	if (ecryptfs_verify_version((*auth_tok)->version)) {
467 		printk(KERN_ERR "Data structure version mismatch. Userspace "
468 		       "tools must match eCryptfs kernel module with major "
469 		       "version [%d] and minor version [%d]\n",
470 		       ECRYPTFS_VERSION_MAJOR, ECRYPTFS_VERSION_MINOR);
471 		rc = -EINVAL;
472 		goto out;
473 	}
474 	if ((*auth_tok)->token_type != ECRYPTFS_PASSWORD
475 	    && (*auth_tok)->token_type != ECRYPTFS_PRIVATE_KEY) {
476 		printk(KERN_ERR "Invalid auth_tok structure "
477 		       "returned from key query\n");
478 		rc = -EINVAL;
479 		goto out;
480 	}
481 out:
482 	return rc;
483 }
484 
485 static int
ecryptfs_find_global_auth_tok_for_sig(struct key ** auth_tok_key,struct ecryptfs_auth_tok ** auth_tok,struct ecryptfs_mount_crypt_stat * mount_crypt_stat,char * sig)486 ecryptfs_find_global_auth_tok_for_sig(
487 	struct key **auth_tok_key,
488 	struct ecryptfs_auth_tok **auth_tok,
489 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat, char *sig)
490 {
491 	struct ecryptfs_global_auth_tok *walker;
492 	int rc = 0;
493 
494 	(*auth_tok_key) = NULL;
495 	(*auth_tok) = NULL;
496 	mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
497 	list_for_each_entry(walker,
498 			    &mount_crypt_stat->global_auth_tok_list,
499 			    mount_crypt_stat_list) {
500 		if (memcmp(walker->sig, sig, ECRYPTFS_SIG_SIZE_HEX))
501 			continue;
502 
503 		if (walker->flags & ECRYPTFS_AUTH_TOK_INVALID) {
504 			rc = -EINVAL;
505 			goto out;
506 		}
507 
508 		rc = key_validate(walker->global_auth_tok_key);
509 		if (rc) {
510 			if (rc == -EKEYEXPIRED)
511 				goto out;
512 			goto out_invalid_auth_tok;
513 		}
514 
515 		down_write(&(walker->global_auth_tok_key->sem));
516 		rc = ecryptfs_verify_auth_tok_from_key(
517 				walker->global_auth_tok_key, auth_tok);
518 		if (rc)
519 			goto out_invalid_auth_tok_unlock;
520 
521 		(*auth_tok_key) = walker->global_auth_tok_key;
522 		key_get(*auth_tok_key);
523 		goto out;
524 	}
525 	rc = -ENOENT;
526 	goto out;
527 out_invalid_auth_tok_unlock:
528 	up_write(&(walker->global_auth_tok_key->sem));
529 out_invalid_auth_tok:
530 	printk(KERN_WARNING "Invalidating auth tok with sig = [%s]\n", sig);
531 	walker->flags |= ECRYPTFS_AUTH_TOK_INVALID;
532 	key_put(walker->global_auth_tok_key);
533 	walker->global_auth_tok_key = NULL;
534 out:
535 	mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
536 	return rc;
537 }
538 
539 /**
540  * ecryptfs_find_auth_tok_for_sig
541  * @auth_tok_key: key containing the authentication token
542  * @auth_tok: Set to the matching auth_tok; NULL if not found
543  * @mount_crypt_stat: inode crypt_stat crypto context
544  * @sig: Sig of auth_tok to find
545  *
546  * For now, this function simply looks at the registered auth_tok's
547  * linked off the mount_crypt_stat, so all the auth_toks that can be
548  * used must be registered at mount time. This function could
549  * potentially try a lot harder to find auth_tok's (e.g., by calling
550  * out to ecryptfsd to dynamically retrieve an auth_tok object) so
551  * that static registration of auth_tok's will no longer be necessary.
552  *
553  * Returns zero on no error; non-zero on error
554  */
555 static int
ecryptfs_find_auth_tok_for_sig(struct key ** auth_tok_key,struct ecryptfs_auth_tok ** auth_tok,struct ecryptfs_mount_crypt_stat * mount_crypt_stat,char * sig)556 ecryptfs_find_auth_tok_for_sig(
557 	struct key **auth_tok_key,
558 	struct ecryptfs_auth_tok **auth_tok,
559 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
560 	char *sig)
561 {
562 	int rc = 0;
563 
564 	rc = ecryptfs_find_global_auth_tok_for_sig(auth_tok_key, auth_tok,
565 						   mount_crypt_stat, sig);
566 	if (rc == -ENOENT) {
567 		/* if the flag ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY is set in the
568 		 * mount_crypt_stat structure, we prevent to use auth toks that
569 		 * are not inserted through the ecryptfs_add_global_auth_tok
570 		 * function.
571 		 */
572 		if (mount_crypt_stat->flags
573 				& ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
574 			return -EINVAL;
575 
576 		rc = ecryptfs_keyring_auth_tok_for_sig(auth_tok_key, auth_tok,
577 						       sig);
578 	}
579 	return rc;
580 }
581 
582 /*
583  * write_tag_70_packet can gobble a lot of stack space. We stuff most
584  * of the function's parameters in a kmalloc'd struct to help reduce
585  * eCryptfs' overall stack usage.
586  */
587 struct ecryptfs_write_tag_70_packet_silly_stack {
588 	u8 cipher_code;
589 	size_t max_packet_size;
590 	size_t packet_size_len;
591 	size_t block_aligned_filename_size;
592 	size_t block_size;
593 	size_t i;
594 	size_t j;
595 	size_t num_rand_bytes;
596 	struct mutex *tfm_mutex;
597 	char *block_aligned_filename;
598 	struct ecryptfs_auth_tok *auth_tok;
599 	struct scatterlist src_sg[2];
600 	struct scatterlist dst_sg[2];
601 	struct crypto_skcipher *skcipher_tfm;
602 	struct skcipher_request *skcipher_req;
603 	char iv[ECRYPTFS_MAX_IV_BYTES];
604 	char hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
605 	char tmp_hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
606 	struct crypto_shash *hash_tfm;
607 	struct shash_desc *hash_desc;
608 };
609 
610 /*
611  * write_tag_70_packet - Write encrypted filename (EFN) packet against FNEK
612  * @filename: NULL-terminated filename string
613  *
614  * This is the simplest mechanism for achieving filename encryption in
615  * eCryptfs. It encrypts the given filename with the mount-wide
616  * filename encryption key (FNEK) and stores it in a packet to @dest,
617  * which the callee will encode and write directly into the dentry
618  * name.
619  */
620 int
ecryptfs_write_tag_70_packet(char * dest,size_t * remaining_bytes,size_t * packet_size,struct ecryptfs_mount_crypt_stat * mount_crypt_stat,char * filename,size_t filename_size)621 ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
622 			     size_t *packet_size,
623 			     struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
624 			     char *filename, size_t filename_size)
625 {
626 	struct ecryptfs_write_tag_70_packet_silly_stack *s;
627 	struct key *auth_tok_key = NULL;
628 	int rc = 0;
629 
630 	s = kzalloc(sizeof(*s), GFP_KERNEL);
631 	if (!s)
632 		return -ENOMEM;
633 
634 	(*packet_size) = 0;
635 	rc = ecryptfs_find_auth_tok_for_sig(
636 		&auth_tok_key,
637 		&s->auth_tok, mount_crypt_stat,
638 		mount_crypt_stat->global_default_fnek_sig);
639 	if (rc) {
640 		printk(KERN_ERR "%s: Error attempting to find auth tok for "
641 		       "fnek sig [%s]; rc = [%d]\n", __func__,
642 		       mount_crypt_stat->global_default_fnek_sig, rc);
643 		goto out;
644 	}
645 	rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(
646 		&s->skcipher_tfm,
647 		&s->tfm_mutex, mount_crypt_stat->global_default_fn_cipher_name);
648 	if (unlikely(rc)) {
649 		printk(KERN_ERR "Internal error whilst attempting to get "
650 		       "tfm and mutex for cipher name [%s]; rc = [%d]\n",
651 		       mount_crypt_stat->global_default_fn_cipher_name, rc);
652 		goto out;
653 	}
654 	mutex_lock(s->tfm_mutex);
655 	s->block_size = crypto_skcipher_blocksize(s->skcipher_tfm);
656 	/* Plus one for the \0 separator between the random prefix
657 	 * and the plaintext filename */
658 	s->num_rand_bytes = (ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES + 1);
659 	s->block_aligned_filename_size = (s->num_rand_bytes + filename_size);
660 	if ((s->block_aligned_filename_size % s->block_size) != 0) {
661 		s->num_rand_bytes += (s->block_size
662 				      - (s->block_aligned_filename_size
663 					 % s->block_size));
664 		s->block_aligned_filename_size = (s->num_rand_bytes
665 						  + filename_size);
666 	}
667 	/* Octet 0: Tag 70 identifier
668 	 * Octets 1-N1: Tag 70 packet size (includes cipher identifier
669 	 *              and block-aligned encrypted filename size)
670 	 * Octets N1-N2: FNEK sig (ECRYPTFS_SIG_SIZE)
671 	 * Octet N2-N3: Cipher identifier (1 octet)
672 	 * Octets N3-N4: Block-aligned encrypted filename
673 	 *  - Consists of a minimum number of random characters, a \0
674 	 *    separator, and then the filename */
675 	s->max_packet_size = (ECRYPTFS_TAG_70_MAX_METADATA_SIZE
676 			      + s->block_aligned_filename_size);
677 	if (!dest) {
678 		(*packet_size) = s->max_packet_size;
679 		goto out_unlock;
680 	}
681 	if (s->max_packet_size > (*remaining_bytes)) {
682 		printk(KERN_WARNING "%s: Require [%zd] bytes to write; only "
683 		       "[%zd] available\n", __func__, s->max_packet_size,
684 		       (*remaining_bytes));
685 		rc = -EINVAL;
686 		goto out_unlock;
687 	}
688 
689 	s->skcipher_req = skcipher_request_alloc(s->skcipher_tfm, GFP_KERNEL);
690 	if (!s->skcipher_req) {
691 		printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
692 		       "skcipher_request_alloc for %s\n", __func__,
693 		       crypto_skcipher_driver_name(s->skcipher_tfm));
694 		rc = -ENOMEM;
695 		goto out_unlock;
696 	}
697 
698 	skcipher_request_set_callback(s->skcipher_req,
699 				      CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
700 
701 	s->block_aligned_filename = kzalloc(s->block_aligned_filename_size,
702 					    GFP_KERNEL);
703 	if (!s->block_aligned_filename) {
704 		rc = -ENOMEM;
705 		goto out_unlock;
706 	}
707 	dest[s->i++] = ECRYPTFS_TAG_70_PACKET_TYPE;
708 	rc = ecryptfs_write_packet_length(&dest[s->i],
709 					  (ECRYPTFS_SIG_SIZE
710 					   + 1 /* Cipher code */
711 					   + s->block_aligned_filename_size),
712 					  &s->packet_size_len);
713 	if (rc) {
714 		printk(KERN_ERR "%s: Error generating tag 70 packet "
715 		       "header; cannot generate packet length; rc = [%d]\n",
716 		       __func__, rc);
717 		goto out_free_unlock;
718 	}
719 	s->i += s->packet_size_len;
720 	ecryptfs_from_hex(&dest[s->i],
721 			  mount_crypt_stat->global_default_fnek_sig,
722 			  ECRYPTFS_SIG_SIZE);
723 	s->i += ECRYPTFS_SIG_SIZE;
724 	s->cipher_code = ecryptfs_code_for_cipher_string(
725 		mount_crypt_stat->global_default_fn_cipher_name,
726 		mount_crypt_stat->global_default_fn_cipher_key_bytes);
727 	if (s->cipher_code == 0) {
728 		printk(KERN_WARNING "%s: Unable to generate code for "
729 		       "cipher [%s] with key bytes [%zd]\n", __func__,
730 		       mount_crypt_stat->global_default_fn_cipher_name,
731 		       mount_crypt_stat->global_default_fn_cipher_key_bytes);
732 		rc = -EINVAL;
733 		goto out_free_unlock;
734 	}
735 	dest[s->i++] = s->cipher_code;
736 	/* TODO: Support other key modules than passphrase for
737 	 * filename encryption */
738 	if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
739 		rc = -EOPNOTSUPP;
740 		printk(KERN_INFO "%s: Filename encryption only supports "
741 		       "password tokens\n", __func__);
742 		goto out_free_unlock;
743 	}
744 	s->hash_tfm = crypto_alloc_shash(ECRYPTFS_TAG_70_DIGEST, 0, 0);
745 	if (IS_ERR(s->hash_tfm)) {
746 			rc = PTR_ERR(s->hash_tfm);
747 			printk(KERN_ERR "%s: Error attempting to "
748 			       "allocate hash crypto context; rc = [%d]\n",
749 			       __func__, rc);
750 			goto out_free_unlock;
751 	}
752 
753 	s->hash_desc = kmalloc(sizeof(*s->hash_desc) +
754 			       crypto_shash_descsize(s->hash_tfm), GFP_KERNEL);
755 	if (!s->hash_desc) {
756 		rc = -ENOMEM;
757 		goto out_release_free_unlock;
758 	}
759 
760 	s->hash_desc->tfm = s->hash_tfm;
761 
762 	rc = crypto_shash_digest(s->hash_desc,
763 				 (u8 *)s->auth_tok->token.password.session_key_encryption_key,
764 				 s->auth_tok->token.password.session_key_encryption_key_bytes,
765 				 s->hash);
766 	if (rc) {
767 		printk(KERN_ERR
768 		       "%s: Error computing crypto hash; rc = [%d]\n",
769 		       __func__, rc);
770 		goto out_release_free_unlock;
771 	}
772 	for (s->j = 0; s->j < (s->num_rand_bytes - 1); s->j++) {
773 		s->block_aligned_filename[s->j] =
774 			s->hash[(s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)];
775 		if ((s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)
776 		    == (ECRYPTFS_TAG_70_DIGEST_SIZE - 1)) {
777 			rc = crypto_shash_digest(s->hash_desc, (u8 *)s->hash,
778 						ECRYPTFS_TAG_70_DIGEST_SIZE,
779 						s->tmp_hash);
780 			if (rc) {
781 				printk(KERN_ERR
782 				       "%s: Error computing crypto hash; "
783 				       "rc = [%d]\n", __func__, rc);
784 				goto out_release_free_unlock;
785 			}
786 			memcpy(s->hash, s->tmp_hash,
787 			       ECRYPTFS_TAG_70_DIGEST_SIZE);
788 		}
789 		if (s->block_aligned_filename[s->j] == '\0')
790 			s->block_aligned_filename[s->j] = ECRYPTFS_NON_NULL;
791 	}
792 	memcpy(&s->block_aligned_filename[s->num_rand_bytes], filename,
793 	       filename_size);
794 	rc = virt_to_scatterlist(s->block_aligned_filename,
795 				 s->block_aligned_filename_size, s->src_sg, 2);
796 	if (rc < 1) {
797 		printk(KERN_ERR "%s: Internal error whilst attempting to "
798 		       "convert filename memory to scatterlist; rc = [%d]. "
799 		       "block_aligned_filename_size = [%zd]\n", __func__, rc,
800 		       s->block_aligned_filename_size);
801 		goto out_release_free_unlock;
802 	}
803 	rc = virt_to_scatterlist(&dest[s->i], s->block_aligned_filename_size,
804 				 s->dst_sg, 2);
805 	if (rc < 1) {
806 		printk(KERN_ERR "%s: Internal error whilst attempting to "
807 		       "convert encrypted filename memory to scatterlist; "
808 		       "rc = [%d]. block_aligned_filename_size = [%zd]\n",
809 		       __func__, rc, s->block_aligned_filename_size);
810 		goto out_release_free_unlock;
811 	}
812 	/* The characters in the first block effectively do the job
813 	 * of the IV here, so we just use 0's for the IV. Note the
814 	 * constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
815 	 * >= ECRYPTFS_MAX_IV_BYTES. */
816 	rc = crypto_skcipher_setkey(
817 		s->skcipher_tfm,
818 		s->auth_tok->token.password.session_key_encryption_key,
819 		mount_crypt_stat->global_default_fn_cipher_key_bytes);
820 	if (rc < 0) {
821 		printk(KERN_ERR "%s: Error setting key for crypto context; "
822 		       "rc = [%d]. s->auth_tok->token.password.session_key_"
823 		       "encryption_key = [0x%p]; mount_crypt_stat->"
824 		       "global_default_fn_cipher_key_bytes = [%zd]\n", __func__,
825 		       rc,
826 		       s->auth_tok->token.password.session_key_encryption_key,
827 		       mount_crypt_stat->global_default_fn_cipher_key_bytes);
828 		goto out_release_free_unlock;
829 	}
830 	skcipher_request_set_crypt(s->skcipher_req, s->src_sg, s->dst_sg,
831 				   s->block_aligned_filename_size, s->iv);
832 	rc = crypto_skcipher_encrypt(s->skcipher_req);
833 	if (rc) {
834 		printk(KERN_ERR "%s: Error attempting to encrypt filename; "
835 		       "rc = [%d]\n", __func__, rc);
836 		goto out_release_free_unlock;
837 	}
838 	s->i += s->block_aligned_filename_size;
839 	(*packet_size) = s->i;
840 	(*remaining_bytes) -= (*packet_size);
841 out_release_free_unlock:
842 	crypto_free_shash(s->hash_tfm);
843 out_free_unlock:
844 	kfree_sensitive(s->block_aligned_filename);
845 out_unlock:
846 	mutex_unlock(s->tfm_mutex);
847 out:
848 	if (auth_tok_key) {
849 		up_write(&(auth_tok_key->sem));
850 		key_put(auth_tok_key);
851 	}
852 	skcipher_request_free(s->skcipher_req);
853 	kfree_sensitive(s->hash_desc);
854 	kfree(s);
855 	return rc;
856 }
857 
858 struct ecryptfs_parse_tag_70_packet_silly_stack {
859 	u8 cipher_code;
860 	size_t max_packet_size;
861 	size_t packet_size_len;
862 	size_t parsed_tag_70_packet_size;
863 	size_t block_aligned_filename_size;
864 	size_t block_size;
865 	size_t i;
866 	struct mutex *tfm_mutex;
867 	char *decrypted_filename;
868 	struct ecryptfs_auth_tok *auth_tok;
869 	struct scatterlist src_sg[2];
870 	struct scatterlist dst_sg[2];
871 	struct crypto_skcipher *skcipher_tfm;
872 	struct skcipher_request *skcipher_req;
873 	char fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX + 1];
874 	char iv[ECRYPTFS_MAX_IV_BYTES];
875 	char cipher_string[ECRYPTFS_MAX_CIPHER_NAME_SIZE + 1];
876 };
877 
878 /**
879  * ecryptfs_parse_tag_70_packet - Parse and process FNEK-encrypted passphrase packet
880  * @filename: This function kmalloc's the memory for the filename
881  * @filename_size: This function sets this to the amount of memory
882  *                 kmalloc'd for the filename
883  * @packet_size: This function sets this to the the number of octets
884  *               in the packet parsed
885  * @mount_crypt_stat: The mount-wide cryptographic context
886  * @data: The memory location containing the start of the tag 70
887  *        packet
888  * @max_packet_size: The maximum legal size of the packet to be parsed
889  *                   from @data
890  *
891  * Returns zero on success; non-zero otherwise
892  */
893 int
ecryptfs_parse_tag_70_packet(char ** filename,size_t * filename_size,size_t * packet_size,struct ecryptfs_mount_crypt_stat * mount_crypt_stat,char * data,size_t max_packet_size)894 ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
895 			     size_t *packet_size,
896 			     struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
897 			     char *data, size_t max_packet_size)
898 {
899 	struct ecryptfs_parse_tag_70_packet_silly_stack *s;
900 	struct key *auth_tok_key = NULL;
901 	int rc = 0;
902 
903 	(*packet_size) = 0;
904 	(*filename_size) = 0;
905 	(*filename) = NULL;
906 	s = kzalloc(sizeof(*s), GFP_KERNEL);
907 	if (!s)
908 		return -ENOMEM;
909 
910 	if (max_packet_size < ECRYPTFS_TAG_70_MIN_METADATA_SIZE) {
911 		printk(KERN_WARNING "%s: max_packet_size is [%zd]; it must be "
912 		       "at least [%d]\n", __func__, max_packet_size,
913 		       ECRYPTFS_TAG_70_MIN_METADATA_SIZE);
914 		rc = -EINVAL;
915 		goto out;
916 	}
917 	/* Octet 0: Tag 70 identifier
918 	 * Octets 1-N1: Tag 70 packet size (includes cipher identifier
919 	 *              and block-aligned encrypted filename size)
920 	 * Octets N1-N2: FNEK sig (ECRYPTFS_SIG_SIZE)
921 	 * Octet N2-N3: Cipher identifier (1 octet)
922 	 * Octets N3-N4: Block-aligned encrypted filename
923 	 *  - Consists of a minimum number of random numbers, a \0
924 	 *    separator, and then the filename */
925 	if (data[(*packet_size)++] != ECRYPTFS_TAG_70_PACKET_TYPE) {
926 		printk(KERN_WARNING "%s: Invalid packet tag [0x%.2x]; must be "
927 		       "tag [0x%.2x]\n", __func__,
928 		       data[((*packet_size) - 1)], ECRYPTFS_TAG_70_PACKET_TYPE);
929 		rc = -EINVAL;
930 		goto out;
931 	}
932 	rc = ecryptfs_parse_packet_length(&data[(*packet_size)],
933 					  &s->parsed_tag_70_packet_size,
934 					  &s->packet_size_len);
935 	if (rc) {
936 		printk(KERN_WARNING "%s: Error parsing packet length; "
937 		       "rc = [%d]\n", __func__, rc);
938 		goto out;
939 	}
940 	s->block_aligned_filename_size = (s->parsed_tag_70_packet_size
941 					  - ECRYPTFS_SIG_SIZE - 1);
942 	if ((1 + s->packet_size_len + s->parsed_tag_70_packet_size)
943 	    > max_packet_size) {
944 		printk(KERN_WARNING "%s: max_packet_size is [%zd]; real packet "
945 		       "size is [%zd]\n", __func__, max_packet_size,
946 		       (1 + s->packet_size_len + 1
947 			+ s->block_aligned_filename_size));
948 		rc = -EINVAL;
949 		goto out;
950 	}
951 	(*packet_size) += s->packet_size_len;
952 	ecryptfs_to_hex(s->fnek_sig_hex, &data[(*packet_size)],
953 			ECRYPTFS_SIG_SIZE);
954 	s->fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX] = '\0';
955 	(*packet_size) += ECRYPTFS_SIG_SIZE;
956 	s->cipher_code = data[(*packet_size)++];
957 	rc = ecryptfs_cipher_code_to_string(s->cipher_string, s->cipher_code);
958 	if (rc) {
959 		printk(KERN_WARNING "%s: Cipher code [%d] is invalid\n",
960 		       __func__, s->cipher_code);
961 		goto out;
962 	}
963 	rc = ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
964 					    &s->auth_tok, mount_crypt_stat,
965 					    s->fnek_sig_hex);
966 	if (rc) {
967 		printk(KERN_ERR "%s: Error attempting to find auth tok for "
968 		       "fnek sig [%s]; rc = [%d]\n", __func__, s->fnek_sig_hex,
969 		       rc);
970 		goto out;
971 	}
972 	rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&s->skcipher_tfm,
973 							&s->tfm_mutex,
974 							s->cipher_string);
975 	if (unlikely(rc)) {
976 		printk(KERN_ERR "Internal error whilst attempting to get "
977 		       "tfm and mutex for cipher name [%s]; rc = [%d]\n",
978 		       s->cipher_string, rc);
979 		goto out;
980 	}
981 	mutex_lock(s->tfm_mutex);
982 	rc = virt_to_scatterlist(&data[(*packet_size)],
983 				 s->block_aligned_filename_size, s->src_sg, 2);
984 	if (rc < 1) {
985 		printk(KERN_ERR "%s: Internal error whilst attempting to "
986 		       "convert encrypted filename memory to scatterlist; "
987 		       "rc = [%d]. block_aligned_filename_size = [%zd]\n",
988 		       __func__, rc, s->block_aligned_filename_size);
989 		goto out_unlock;
990 	}
991 	(*packet_size) += s->block_aligned_filename_size;
992 	s->decrypted_filename = kmalloc(s->block_aligned_filename_size,
993 					GFP_KERNEL);
994 	if (!s->decrypted_filename) {
995 		rc = -ENOMEM;
996 		goto out_unlock;
997 	}
998 	rc = virt_to_scatterlist(s->decrypted_filename,
999 				 s->block_aligned_filename_size, s->dst_sg, 2);
1000 	if (rc < 1) {
1001 		printk(KERN_ERR "%s: Internal error whilst attempting to "
1002 		       "convert decrypted filename memory to scatterlist; "
1003 		       "rc = [%d]. block_aligned_filename_size = [%zd]\n",
1004 		       __func__, rc, s->block_aligned_filename_size);
1005 		goto out_free_unlock;
1006 	}
1007 
1008 	s->skcipher_req = skcipher_request_alloc(s->skcipher_tfm, GFP_KERNEL);
1009 	if (!s->skcipher_req) {
1010 		printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
1011 		       "skcipher_request_alloc for %s\n", __func__,
1012 		       crypto_skcipher_driver_name(s->skcipher_tfm));
1013 		rc = -ENOMEM;
1014 		goto out_free_unlock;
1015 	}
1016 
1017 	skcipher_request_set_callback(s->skcipher_req,
1018 				      CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
1019 
1020 	/* The characters in the first block effectively do the job of
1021 	 * the IV here, so we just use 0's for the IV. Note the
1022 	 * constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
1023 	 * >= ECRYPTFS_MAX_IV_BYTES. */
1024 	/* TODO: Support other key modules than passphrase for
1025 	 * filename encryption */
1026 	if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
1027 		rc = -EOPNOTSUPP;
1028 		printk(KERN_INFO "%s: Filename encryption only supports "
1029 		       "password tokens\n", __func__);
1030 		goto out_free_unlock;
1031 	}
1032 	rc = crypto_skcipher_setkey(
1033 		s->skcipher_tfm,
1034 		s->auth_tok->token.password.session_key_encryption_key,
1035 		mount_crypt_stat->global_default_fn_cipher_key_bytes);
1036 	if (rc < 0) {
1037 		printk(KERN_ERR "%s: Error setting key for crypto context; "
1038 		       "rc = [%d]. s->auth_tok->token.password.session_key_"
1039 		       "encryption_key = [0x%p]; mount_crypt_stat->"
1040 		       "global_default_fn_cipher_key_bytes = [%zd]\n", __func__,
1041 		       rc,
1042 		       s->auth_tok->token.password.session_key_encryption_key,
1043 		       mount_crypt_stat->global_default_fn_cipher_key_bytes);
1044 		goto out_free_unlock;
1045 	}
1046 	skcipher_request_set_crypt(s->skcipher_req, s->src_sg, s->dst_sg,
1047 				   s->block_aligned_filename_size, s->iv);
1048 	rc = crypto_skcipher_decrypt(s->skcipher_req);
1049 	if (rc) {
1050 		printk(KERN_ERR "%s: Error attempting to decrypt filename; "
1051 		       "rc = [%d]\n", __func__, rc);
1052 		goto out_free_unlock;
1053 	}
1054 
1055 	while (s->i < s->block_aligned_filename_size &&
1056 	       s->decrypted_filename[s->i] != '\0')
1057 		s->i++;
1058 	if (s->i == s->block_aligned_filename_size) {
1059 		printk(KERN_WARNING "%s: Invalid tag 70 packet; could not "
1060 		       "find valid separator between random characters and "
1061 		       "the filename\n", __func__);
1062 		rc = -EINVAL;
1063 		goto out_free_unlock;
1064 	}
1065 	s->i++;
1066 	(*filename_size) = (s->block_aligned_filename_size - s->i);
1067 	if (!((*filename_size) > 0 && (*filename_size < PATH_MAX))) {
1068 		printk(KERN_WARNING "%s: Filename size is [%zd], which is "
1069 		       "invalid\n", __func__, (*filename_size));
1070 		rc = -EINVAL;
1071 		goto out_free_unlock;
1072 	}
1073 	(*filename) = kmalloc(((*filename_size) + 1), GFP_KERNEL);
1074 	if (!(*filename)) {
1075 		rc = -ENOMEM;
1076 		goto out_free_unlock;
1077 	}
1078 	memcpy((*filename), &s->decrypted_filename[s->i], (*filename_size));
1079 	(*filename)[(*filename_size)] = '\0';
1080 out_free_unlock:
1081 	kfree(s->decrypted_filename);
1082 out_unlock:
1083 	mutex_unlock(s->tfm_mutex);
1084 out:
1085 	if (rc) {
1086 		(*packet_size) = 0;
1087 		(*filename_size) = 0;
1088 		(*filename) = NULL;
1089 	}
1090 	if (auth_tok_key) {
1091 		up_write(&(auth_tok_key->sem));
1092 		key_put(auth_tok_key);
1093 	}
1094 	skcipher_request_free(s->skcipher_req);
1095 	kfree(s);
1096 	return rc;
1097 }
1098 
1099 static int
ecryptfs_get_auth_tok_sig(char ** sig,struct ecryptfs_auth_tok * auth_tok)1100 ecryptfs_get_auth_tok_sig(char **sig, struct ecryptfs_auth_tok *auth_tok)
1101 {
1102 	int rc = 0;
1103 
1104 	(*sig) = NULL;
1105 	switch (auth_tok->token_type) {
1106 	case ECRYPTFS_PASSWORD:
1107 		(*sig) = auth_tok->token.password.signature;
1108 		break;
1109 	case ECRYPTFS_PRIVATE_KEY:
1110 		(*sig) = auth_tok->token.private_key.signature;
1111 		break;
1112 	default:
1113 		printk(KERN_ERR "Cannot get sig for auth_tok of type [%d]\n",
1114 		       auth_tok->token_type);
1115 		rc = -EINVAL;
1116 	}
1117 	return rc;
1118 }
1119 
1120 /**
1121  * decrypt_pki_encrypted_session_key - Decrypt the session key with the given auth_tok.
1122  * @auth_tok: The key authentication token used to decrypt the session key
1123  * @crypt_stat: The cryptographic context
1124  *
1125  * Returns zero on success; non-zero error otherwise.
1126  */
1127 static int
decrypt_pki_encrypted_session_key(struct ecryptfs_auth_tok * auth_tok,struct ecryptfs_crypt_stat * crypt_stat)1128 decrypt_pki_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
1129 				  struct ecryptfs_crypt_stat *crypt_stat)
1130 {
1131 	u8 cipher_code = 0;
1132 	struct ecryptfs_msg_ctx *msg_ctx;
1133 	struct ecryptfs_message *msg = NULL;
1134 	char *auth_tok_sig;
1135 	char *payload = NULL;
1136 	size_t payload_len = 0;
1137 	int rc;
1138 
1139 	rc = ecryptfs_get_auth_tok_sig(&auth_tok_sig, auth_tok);
1140 	if (rc) {
1141 		printk(KERN_ERR "Unrecognized auth tok type: [%d]\n",
1142 		       auth_tok->token_type);
1143 		goto out;
1144 	}
1145 	rc = write_tag_64_packet(auth_tok_sig, &(auth_tok->session_key),
1146 				 &payload, &payload_len);
1147 	if (rc) {
1148 		ecryptfs_printk(KERN_ERR, "Failed to write tag 64 packet\n");
1149 		goto out;
1150 	}
1151 	rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);
1152 	if (rc) {
1153 		ecryptfs_printk(KERN_ERR, "Error sending message to "
1154 				"ecryptfsd: %d\n", rc);
1155 		goto out;
1156 	}
1157 	rc = ecryptfs_wait_for_response(msg_ctx, &msg);
1158 	if (rc) {
1159 		ecryptfs_printk(KERN_ERR, "Failed to receive tag 65 packet "
1160 				"from the user space daemon\n");
1161 		rc = -EIO;
1162 		goto out;
1163 	}
1164 	rc = parse_tag_65_packet(&(auth_tok->session_key),
1165 				 &cipher_code, msg);
1166 	if (rc) {
1167 		printk(KERN_ERR "Failed to parse tag 65 packet; rc = [%d]\n",
1168 		       rc);
1169 		goto out;
1170 	}
1171 	auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1172 	memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
1173 	       auth_tok->session_key.decrypted_key_size);
1174 	crypt_stat->key_size = auth_tok->session_key.decrypted_key_size;
1175 	rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher, cipher_code);
1176 	if (rc) {
1177 		ecryptfs_printk(KERN_ERR, "Cipher code [%d] is invalid\n",
1178 				cipher_code);
1179 		goto out;
1180 	}
1181 	crypt_stat->flags |= ECRYPTFS_KEY_VALID;
1182 	if (ecryptfs_verbosity > 0) {
1183 		ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n");
1184 		ecryptfs_dump_hex(crypt_stat->key,
1185 				  crypt_stat->key_size);
1186 	}
1187 out:
1188 	kfree(msg);
1189 	kfree(payload);
1190 	return rc;
1191 }
1192 
wipe_auth_tok_list(struct list_head * auth_tok_list_head)1193 static void wipe_auth_tok_list(struct list_head *auth_tok_list_head)
1194 {
1195 	struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1196 	struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;
1197 
1198 	list_for_each_entry_safe(auth_tok_list_item, auth_tok_list_item_tmp,
1199 				 auth_tok_list_head, list) {
1200 		list_del(&auth_tok_list_item->list);
1201 		kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1202 				auth_tok_list_item);
1203 	}
1204 }
1205 
1206 struct kmem_cache *ecryptfs_auth_tok_list_item_cache;
1207 
1208 /**
1209  * parse_tag_1_packet
1210  * @crypt_stat: The cryptographic context to modify based on packet contents
1211  * @data: The raw bytes of the packet.
1212  * @auth_tok_list: eCryptfs parses packets into authentication tokens;
1213  *                 a new authentication token will be placed at the
1214  *                 end of this list for this packet.
1215  * @new_auth_tok: Pointer to a pointer to memory that this function
1216  *                allocates; sets the memory address of the pointer to
1217  *                NULL on error. This object is added to the
1218  *                auth_tok_list.
1219  * @packet_size: This function writes the size of the parsed packet
1220  *               into this memory location; zero on error.
1221  * @max_packet_size: The maximum allowable packet size
1222  *
1223  * Returns zero on success; non-zero on error.
1224  */
1225 static int
parse_tag_1_packet(struct ecryptfs_crypt_stat * crypt_stat,unsigned char * data,struct list_head * auth_tok_list,struct ecryptfs_auth_tok ** new_auth_tok,size_t * packet_size,size_t max_packet_size)1226 parse_tag_1_packet(struct ecryptfs_crypt_stat *crypt_stat,
1227 		   unsigned char *data, struct list_head *auth_tok_list,
1228 		   struct ecryptfs_auth_tok **new_auth_tok,
1229 		   size_t *packet_size, size_t max_packet_size)
1230 {
1231 	size_t body_size;
1232 	struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1233 	size_t length_size;
1234 	int rc = 0;
1235 
1236 	(*packet_size) = 0;
1237 	(*new_auth_tok) = NULL;
1238 	/**
1239 	 * This format is inspired by OpenPGP; see RFC 2440
1240 	 * packet tag 1
1241 	 *
1242 	 * Tag 1 identifier (1 byte)
1243 	 * Max Tag 1 packet size (max 3 bytes)
1244 	 * Version (1 byte)
1245 	 * Key identifier (8 bytes; ECRYPTFS_SIG_SIZE)
1246 	 * Cipher identifier (1 byte)
1247 	 * Encrypted key size (arbitrary)
1248 	 *
1249 	 * 12 bytes minimum packet size
1250 	 */
1251 	if (unlikely(max_packet_size < 12)) {
1252 		printk(KERN_ERR "Invalid max packet size; must be >=12\n");
1253 		rc = -EINVAL;
1254 		goto out;
1255 	}
1256 	if (data[(*packet_size)++] != ECRYPTFS_TAG_1_PACKET_TYPE) {
1257 		printk(KERN_ERR "Enter w/ first byte != 0x%.2x\n",
1258 		       ECRYPTFS_TAG_1_PACKET_TYPE);
1259 		rc = -EINVAL;
1260 		goto out;
1261 	}
1262 	/* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
1263 	 * at end of function upon failure */
1264 	auth_tok_list_item =
1265 		kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache,
1266 				  GFP_KERNEL);
1267 	if (!auth_tok_list_item) {
1268 		printk(KERN_ERR "Unable to allocate memory\n");
1269 		rc = -ENOMEM;
1270 		goto out;
1271 	}
1272 	(*new_auth_tok) = &auth_tok_list_item->auth_tok;
1273 	rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1274 					  &length_size);
1275 	if (rc) {
1276 		printk(KERN_WARNING "Error parsing packet length; "
1277 		       "rc = [%d]\n", rc);
1278 		goto out_free;
1279 	}
1280 	if (unlikely(body_size < (ECRYPTFS_SIG_SIZE + 2))) {
1281 		printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1282 		rc = -EINVAL;
1283 		goto out_free;
1284 	}
1285 	(*packet_size) += length_size;
1286 	if (unlikely((*packet_size) + body_size > max_packet_size)) {
1287 		printk(KERN_WARNING "Packet size exceeds max\n");
1288 		rc = -EINVAL;
1289 		goto out_free;
1290 	}
1291 	if (unlikely(data[(*packet_size)++] != 0x03)) {
1292 		printk(KERN_WARNING "Unknown version number [%d]\n",
1293 		       data[(*packet_size) - 1]);
1294 		rc = -EINVAL;
1295 		goto out_free;
1296 	}
1297 	ecryptfs_to_hex((*new_auth_tok)->token.private_key.signature,
1298 			&data[(*packet_size)], ECRYPTFS_SIG_SIZE);
1299 	*packet_size += ECRYPTFS_SIG_SIZE;
1300 	/* This byte is skipped because the kernel does not need to
1301 	 * know which public key encryption algorithm was used */
1302 	(*packet_size)++;
1303 	(*new_auth_tok)->session_key.encrypted_key_size =
1304 		body_size - (ECRYPTFS_SIG_SIZE + 2);
1305 	if ((*new_auth_tok)->session_key.encrypted_key_size
1306 	    > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
1307 		printk(KERN_WARNING "Tag 1 packet contains key larger "
1308 		       "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES\n");
1309 		rc = -EINVAL;
1310 		goto out_free;
1311 	}
1312 	memcpy((*new_auth_tok)->session_key.encrypted_key,
1313 	       &data[(*packet_size)], (body_size - (ECRYPTFS_SIG_SIZE + 2)));
1314 	(*packet_size) += (*new_auth_tok)->session_key.encrypted_key_size;
1315 	(*new_auth_tok)->session_key.flags &=
1316 		~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1317 	(*new_auth_tok)->session_key.flags |=
1318 		ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
1319 	(*new_auth_tok)->token_type = ECRYPTFS_PRIVATE_KEY;
1320 	(*new_auth_tok)->flags = 0;
1321 	(*new_auth_tok)->session_key.flags &=
1322 		~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
1323 	(*new_auth_tok)->session_key.flags &=
1324 		~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
1325 	list_add(&auth_tok_list_item->list, auth_tok_list);
1326 	goto out;
1327 out_free:
1328 	(*new_auth_tok) = NULL;
1329 	memset(auth_tok_list_item, 0,
1330 	       sizeof(struct ecryptfs_auth_tok_list_item));
1331 	kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1332 			auth_tok_list_item);
1333 out:
1334 	if (rc)
1335 		(*packet_size) = 0;
1336 	return rc;
1337 }
1338 
1339 /**
1340  * parse_tag_3_packet
1341  * @crypt_stat: The cryptographic context to modify based on packet
1342  *              contents.
1343  * @data: The raw bytes of the packet.
1344  * @auth_tok_list: eCryptfs parses packets into authentication tokens;
1345  *                 a new authentication token will be placed at the end
1346  *                 of this list for this packet.
1347  * @new_auth_tok: Pointer to a pointer to memory that this function
1348  *                allocates; sets the memory address of the pointer to
1349  *                NULL on error. This object is added to the
1350  *                auth_tok_list.
1351  * @packet_size: This function writes the size of the parsed packet
1352  *               into this memory location; zero on error.
1353  * @max_packet_size: maximum number of bytes to parse
1354  *
1355  * Returns zero on success; non-zero on error.
1356  */
1357 static int
parse_tag_3_packet(struct ecryptfs_crypt_stat * crypt_stat,unsigned char * data,struct list_head * auth_tok_list,struct ecryptfs_auth_tok ** new_auth_tok,size_t * packet_size,size_t max_packet_size)1358 parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat,
1359 		   unsigned char *data, struct list_head *auth_tok_list,
1360 		   struct ecryptfs_auth_tok **new_auth_tok,
1361 		   size_t *packet_size, size_t max_packet_size)
1362 {
1363 	size_t body_size;
1364 	struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1365 	size_t length_size;
1366 	int rc = 0;
1367 
1368 	(*packet_size) = 0;
1369 	(*new_auth_tok) = NULL;
1370 	/**
1371 	 *This format is inspired by OpenPGP; see RFC 2440
1372 	 * packet tag 3
1373 	 *
1374 	 * Tag 3 identifier (1 byte)
1375 	 * Max Tag 3 packet size (max 3 bytes)
1376 	 * Version (1 byte)
1377 	 * Cipher code (1 byte)
1378 	 * S2K specifier (1 byte)
1379 	 * Hash identifier (1 byte)
1380 	 * Salt (ECRYPTFS_SALT_SIZE)
1381 	 * Hash iterations (1 byte)
1382 	 * Encrypted key (arbitrary)
1383 	 *
1384 	 * (ECRYPTFS_SALT_SIZE + 7) minimum packet size
1385 	 */
1386 	if (max_packet_size < (ECRYPTFS_SALT_SIZE + 7)) {
1387 		printk(KERN_ERR "Max packet size too large\n");
1388 		rc = -EINVAL;
1389 		goto out;
1390 	}
1391 	if (data[(*packet_size)++] != ECRYPTFS_TAG_3_PACKET_TYPE) {
1392 		printk(KERN_ERR "First byte != 0x%.2x; invalid packet\n",
1393 		       ECRYPTFS_TAG_3_PACKET_TYPE);
1394 		rc = -EINVAL;
1395 		goto out;
1396 	}
1397 	/* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
1398 	 * at end of function upon failure */
1399 	auth_tok_list_item =
1400 	    kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache, GFP_KERNEL);
1401 	if (!auth_tok_list_item) {
1402 		printk(KERN_ERR "Unable to allocate memory\n");
1403 		rc = -ENOMEM;
1404 		goto out;
1405 	}
1406 	(*new_auth_tok) = &auth_tok_list_item->auth_tok;
1407 	rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1408 					  &length_size);
1409 	if (rc) {
1410 		printk(KERN_WARNING "Error parsing packet length; rc = [%d]\n",
1411 		       rc);
1412 		goto out_free;
1413 	}
1414 	if (unlikely(body_size < (ECRYPTFS_SALT_SIZE + 5))) {
1415 		printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1416 		rc = -EINVAL;
1417 		goto out_free;
1418 	}
1419 	(*packet_size) += length_size;
1420 	if (unlikely((*packet_size) + body_size > max_packet_size)) {
1421 		printk(KERN_ERR "Packet size exceeds max\n");
1422 		rc = -EINVAL;
1423 		goto out_free;
1424 	}
1425 	(*new_auth_tok)->session_key.encrypted_key_size =
1426 		(body_size - (ECRYPTFS_SALT_SIZE + 5));
1427 	if ((*new_auth_tok)->session_key.encrypted_key_size
1428 	    > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
1429 		printk(KERN_WARNING "Tag 3 packet contains key larger "
1430 		       "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES\n");
1431 		rc = -EINVAL;
1432 		goto out_free;
1433 	}
1434 	if (unlikely(data[(*packet_size)++] != 0x04)) {
1435 		printk(KERN_WARNING "Unknown version number [%d]\n",
1436 		       data[(*packet_size) - 1]);
1437 		rc = -EINVAL;
1438 		goto out_free;
1439 	}
1440 	rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher,
1441 					    (u16)data[(*packet_size)]);
1442 	if (rc)
1443 		goto out_free;
1444 	/* A little extra work to differentiate among the AES key
1445 	 * sizes; see RFC2440 */
1446 	switch(data[(*packet_size)++]) {
1447 	case RFC2440_CIPHER_AES_192:
1448 		crypt_stat->key_size = 24;
1449 		break;
1450 	default:
1451 		crypt_stat->key_size =
1452 			(*new_auth_tok)->session_key.encrypted_key_size;
1453 	}
1454 	rc = ecryptfs_init_crypt_ctx(crypt_stat);
1455 	if (rc)
1456 		goto out_free;
1457 	if (unlikely(data[(*packet_size)++] != 0x03)) {
1458 		printk(KERN_WARNING "Only S2K ID 3 is currently supported\n");
1459 		rc = -ENOSYS;
1460 		goto out_free;
1461 	}
1462 	/* TODO: finish the hash mapping */
1463 	switch (data[(*packet_size)++]) {
1464 	case 0x01: /* See RFC2440 for these numbers and their mappings */
1465 		/* Choose MD5 */
1466 		memcpy((*new_auth_tok)->token.password.salt,
1467 		       &data[(*packet_size)], ECRYPTFS_SALT_SIZE);
1468 		(*packet_size) += ECRYPTFS_SALT_SIZE;
1469 		/* This conversion was taken straight from RFC2440 */
1470 		(*new_auth_tok)->token.password.hash_iterations =
1471 			((u32) 16 + (data[(*packet_size)] & 15))
1472 				<< ((data[(*packet_size)] >> 4) + 6);
1473 		(*packet_size)++;
1474 		/* Friendly reminder:
1475 		 * (*new_auth_tok)->session_key.encrypted_key_size =
1476 		 *         (body_size - (ECRYPTFS_SALT_SIZE + 5)); */
1477 		memcpy((*new_auth_tok)->session_key.encrypted_key,
1478 		       &data[(*packet_size)],
1479 		       (*new_auth_tok)->session_key.encrypted_key_size);
1480 		(*packet_size) +=
1481 			(*new_auth_tok)->session_key.encrypted_key_size;
1482 		(*new_auth_tok)->session_key.flags &=
1483 			~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1484 		(*new_auth_tok)->session_key.flags |=
1485 			ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
1486 		(*new_auth_tok)->token.password.hash_algo = 0x01; /* MD5 */
1487 		break;
1488 	default:
1489 		ecryptfs_printk(KERN_ERR, "Unsupported hash algorithm: "
1490 				"[%d]\n", data[(*packet_size) - 1]);
1491 		rc = -ENOSYS;
1492 		goto out_free;
1493 	}
1494 	(*new_auth_tok)->token_type = ECRYPTFS_PASSWORD;
1495 	/* TODO: Parametarize; we might actually want userspace to
1496 	 * decrypt the session key. */
1497 	(*new_auth_tok)->session_key.flags &=
1498 			    ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
1499 	(*new_auth_tok)->session_key.flags &=
1500 			    ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
1501 	list_add(&auth_tok_list_item->list, auth_tok_list);
1502 	goto out;
1503 out_free:
1504 	(*new_auth_tok) = NULL;
1505 	memset(auth_tok_list_item, 0,
1506 	       sizeof(struct ecryptfs_auth_tok_list_item));
1507 	kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1508 			auth_tok_list_item);
1509 out:
1510 	if (rc)
1511 		(*packet_size) = 0;
1512 	return rc;
1513 }
1514 
1515 /**
1516  * parse_tag_11_packet
1517  * @data: The raw bytes of the packet
1518  * @contents: This function writes the data contents of the literal
1519  *            packet into this memory location
1520  * @max_contents_bytes: The maximum number of bytes that this function
1521  *                      is allowed to write into contents
1522  * @tag_11_contents_size: This function writes the size of the parsed
1523  *                        contents into this memory location; zero on
1524  *                        error
1525  * @packet_size: This function writes the size of the parsed packet
1526  *               into this memory location; zero on error
1527  * @max_packet_size: maximum number of bytes to parse
1528  *
1529  * Returns zero on success; non-zero on error.
1530  */
1531 static int
parse_tag_11_packet(unsigned char * data,unsigned char * contents,size_t max_contents_bytes,size_t * tag_11_contents_size,size_t * packet_size,size_t max_packet_size)1532 parse_tag_11_packet(unsigned char *data, unsigned char *contents,
1533 		    size_t max_contents_bytes, size_t *tag_11_contents_size,
1534 		    size_t *packet_size, size_t max_packet_size)
1535 {
1536 	size_t body_size;
1537 	size_t length_size;
1538 	int rc = 0;
1539 
1540 	(*packet_size) = 0;
1541 	(*tag_11_contents_size) = 0;
1542 	/* This format is inspired by OpenPGP; see RFC 2440
1543 	 * packet tag 11
1544 	 *
1545 	 * Tag 11 identifier (1 byte)
1546 	 * Max Tag 11 packet size (max 3 bytes)
1547 	 * Binary format specifier (1 byte)
1548 	 * Filename length (1 byte)
1549 	 * Filename ("_CONSOLE") (8 bytes)
1550 	 * Modification date (4 bytes)
1551 	 * Literal data (arbitrary)
1552 	 *
1553 	 * We need at least 16 bytes of data for the packet to even be
1554 	 * valid.
1555 	 */
1556 	if (max_packet_size < 16) {
1557 		printk(KERN_ERR "Maximum packet size too small\n");
1558 		rc = -EINVAL;
1559 		goto out;
1560 	}
1561 	if (data[(*packet_size)++] != ECRYPTFS_TAG_11_PACKET_TYPE) {
1562 		printk(KERN_WARNING "Invalid tag 11 packet format\n");
1563 		rc = -EINVAL;
1564 		goto out;
1565 	}
1566 	rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1567 					  &length_size);
1568 	if (rc) {
1569 		printk(KERN_WARNING "Invalid tag 11 packet format\n");
1570 		goto out;
1571 	}
1572 	if (body_size < 14) {
1573 		printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1574 		rc = -EINVAL;
1575 		goto out;
1576 	}
1577 	(*packet_size) += length_size;
1578 	(*tag_11_contents_size) = (body_size - 14);
1579 	if (unlikely((*packet_size) + body_size + 1 > max_packet_size)) {
1580 		printk(KERN_ERR "Packet size exceeds max\n");
1581 		rc = -EINVAL;
1582 		goto out;
1583 	}
1584 	if (unlikely((*tag_11_contents_size) > max_contents_bytes)) {
1585 		printk(KERN_ERR "Literal data section in tag 11 packet exceeds "
1586 		       "expected size\n");
1587 		rc = -EINVAL;
1588 		goto out;
1589 	}
1590 	if (data[(*packet_size)++] != 0x62) {
1591 		printk(KERN_WARNING "Unrecognizable packet\n");
1592 		rc = -EINVAL;
1593 		goto out;
1594 	}
1595 	if (data[(*packet_size)++] != 0x08) {
1596 		printk(KERN_WARNING "Unrecognizable packet\n");
1597 		rc = -EINVAL;
1598 		goto out;
1599 	}
1600 	(*packet_size) += 12; /* Ignore filename and modification date */
1601 	memcpy(contents, &data[(*packet_size)], (*tag_11_contents_size));
1602 	(*packet_size) += (*tag_11_contents_size);
1603 out:
1604 	if (rc) {
1605 		(*packet_size) = 0;
1606 		(*tag_11_contents_size) = 0;
1607 	}
1608 	return rc;
1609 }
1610 
ecryptfs_keyring_auth_tok_for_sig(struct key ** auth_tok_key,struct ecryptfs_auth_tok ** auth_tok,char * sig)1611 int ecryptfs_keyring_auth_tok_for_sig(struct key **auth_tok_key,
1612 				      struct ecryptfs_auth_tok **auth_tok,
1613 				      char *sig)
1614 {
1615 	int rc = 0;
1616 
1617 	(*auth_tok_key) = request_key(&key_type_user, sig, NULL);
1618 	if (IS_ERR(*auth_tok_key)) {
1619 		(*auth_tok_key) = ecryptfs_get_encrypted_key(sig);
1620 		if (IS_ERR(*auth_tok_key)) {
1621 			printk(KERN_ERR "Could not find key with description: [%s]\n",
1622 			      sig);
1623 			rc = process_request_key_err(PTR_ERR(*auth_tok_key));
1624 			(*auth_tok_key) = NULL;
1625 			goto out;
1626 		}
1627 	}
1628 	down_write(&(*auth_tok_key)->sem);
1629 	rc = ecryptfs_verify_auth_tok_from_key(*auth_tok_key, auth_tok);
1630 	if (rc) {
1631 		up_write(&(*auth_tok_key)->sem);
1632 		key_put(*auth_tok_key);
1633 		(*auth_tok_key) = NULL;
1634 		goto out;
1635 	}
1636 out:
1637 	return rc;
1638 }
1639 
1640 /**
1641  * decrypt_passphrase_encrypted_session_key - Decrypt the session key with the given auth_tok.
1642  * @auth_tok: The passphrase authentication token to use to encrypt the FEK
1643  * @crypt_stat: The cryptographic context
1644  *
1645  * Returns zero on success; non-zero error otherwise
1646  */
1647 static int
decrypt_passphrase_encrypted_session_key(struct ecryptfs_auth_tok * auth_tok,struct ecryptfs_crypt_stat * crypt_stat)1648 decrypt_passphrase_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
1649 					 struct ecryptfs_crypt_stat *crypt_stat)
1650 {
1651 	struct scatterlist dst_sg[2];
1652 	struct scatterlist src_sg[2];
1653 	struct mutex *tfm_mutex;
1654 	struct crypto_skcipher *tfm;
1655 	struct skcipher_request *req = NULL;
1656 	int rc = 0;
1657 
1658 	if (unlikely(ecryptfs_verbosity > 0)) {
1659 		ecryptfs_printk(
1660 			KERN_DEBUG, "Session key encryption key (size [%d]):\n",
1661 			auth_tok->token.password.session_key_encryption_key_bytes);
1662 		ecryptfs_dump_hex(
1663 			auth_tok->token.password.session_key_encryption_key,
1664 			auth_tok->token.password.session_key_encryption_key_bytes);
1665 	}
1666 	rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex,
1667 							crypt_stat->cipher);
1668 	if (unlikely(rc)) {
1669 		printk(KERN_ERR "Internal error whilst attempting to get "
1670 		       "tfm and mutex for cipher name [%s]; rc = [%d]\n",
1671 		       crypt_stat->cipher, rc);
1672 		goto out;
1673 	}
1674 	rc = virt_to_scatterlist(auth_tok->session_key.encrypted_key,
1675 				 auth_tok->session_key.encrypted_key_size,
1676 				 src_sg, 2);
1677 	if (rc < 1 || rc > 2) {
1678 		printk(KERN_ERR "Internal error whilst attempting to convert "
1679 			"auth_tok->session_key.encrypted_key to scatterlist; "
1680 			"expected rc = 1; got rc = [%d]. "
1681 		       "auth_tok->session_key.encrypted_key_size = [%d]\n", rc,
1682 			auth_tok->session_key.encrypted_key_size);
1683 		goto out;
1684 	}
1685 	auth_tok->session_key.decrypted_key_size =
1686 		auth_tok->session_key.encrypted_key_size;
1687 	rc = virt_to_scatterlist(auth_tok->session_key.decrypted_key,
1688 				 auth_tok->session_key.decrypted_key_size,
1689 				 dst_sg, 2);
1690 	if (rc < 1 || rc > 2) {
1691 		printk(KERN_ERR "Internal error whilst attempting to convert "
1692 			"auth_tok->session_key.decrypted_key to scatterlist; "
1693 			"expected rc = 1; got rc = [%d]\n", rc);
1694 		goto out;
1695 	}
1696 	mutex_lock(tfm_mutex);
1697 	req = skcipher_request_alloc(tfm, GFP_KERNEL);
1698 	if (!req) {
1699 		mutex_unlock(tfm_mutex);
1700 		printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
1701 		       "skcipher_request_alloc for %s\n", __func__,
1702 		       crypto_skcipher_driver_name(tfm));
1703 		rc = -ENOMEM;
1704 		goto out;
1705 	}
1706 
1707 	skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP,
1708 				      NULL, NULL);
1709 	rc = crypto_skcipher_setkey(
1710 		tfm, auth_tok->token.password.session_key_encryption_key,
1711 		crypt_stat->key_size);
1712 	if (unlikely(rc < 0)) {
1713 		mutex_unlock(tfm_mutex);
1714 		printk(KERN_ERR "Error setting key for crypto context\n");
1715 		rc = -EINVAL;
1716 		goto out;
1717 	}
1718 	skcipher_request_set_crypt(req, src_sg, dst_sg,
1719 				   auth_tok->session_key.encrypted_key_size,
1720 				   NULL);
1721 	rc = crypto_skcipher_decrypt(req);
1722 	mutex_unlock(tfm_mutex);
1723 	if (unlikely(rc)) {
1724 		printk(KERN_ERR "Error decrypting; rc = [%d]\n", rc);
1725 		goto out;
1726 	}
1727 	auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1728 	memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
1729 	       auth_tok->session_key.decrypted_key_size);
1730 	crypt_stat->flags |= ECRYPTFS_KEY_VALID;
1731 	if (unlikely(ecryptfs_verbosity > 0)) {
1732 		ecryptfs_printk(KERN_DEBUG, "FEK of size [%zd]:\n",
1733 				crypt_stat->key_size);
1734 		ecryptfs_dump_hex(crypt_stat->key,
1735 				  crypt_stat->key_size);
1736 	}
1737 out:
1738 	skcipher_request_free(req);
1739 	return rc;
1740 }
1741 
1742 /**
1743  * ecryptfs_parse_packet_set
1744  * @crypt_stat: The cryptographic context
1745  * @src: Virtual address of region of memory containing the packets
1746  * @ecryptfs_dentry: The eCryptfs dentry associated with the packet set
1747  *
1748  * Get crypt_stat to have the file's session key if the requisite key
1749  * is available to decrypt the session key.
1750  *
1751  * Returns Zero if a valid authentication token was retrieved and
1752  * processed; negative value for file not encrypted or for error
1753  * conditions.
1754  */
ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat * crypt_stat,unsigned char * src,struct dentry * ecryptfs_dentry)1755 int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
1756 			      unsigned char *src,
1757 			      struct dentry *ecryptfs_dentry)
1758 {
1759 	size_t i = 0;
1760 	size_t found_auth_tok;
1761 	size_t next_packet_is_auth_tok_packet;
1762 	struct list_head auth_tok_list;
1763 	struct ecryptfs_auth_tok *matching_auth_tok;
1764 	struct ecryptfs_auth_tok *candidate_auth_tok;
1765 	char *candidate_auth_tok_sig;
1766 	size_t packet_size;
1767 	struct ecryptfs_auth_tok *new_auth_tok;
1768 	unsigned char sig_tmp_space[ECRYPTFS_SIG_SIZE];
1769 	struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1770 	size_t tag_11_contents_size;
1771 	size_t tag_11_packet_size;
1772 	struct key *auth_tok_key = NULL;
1773 	int rc = 0;
1774 
1775 	INIT_LIST_HEAD(&auth_tok_list);
1776 	/* Parse the header to find as many packets as we can; these will be
1777 	 * added the our &auth_tok_list */
1778 	next_packet_is_auth_tok_packet = 1;
1779 	while (next_packet_is_auth_tok_packet) {
1780 		size_t max_packet_size = ((PAGE_SIZE - 8) - i);
1781 
1782 		switch (src[i]) {
1783 		case ECRYPTFS_TAG_3_PACKET_TYPE:
1784 			rc = parse_tag_3_packet(crypt_stat,
1785 						(unsigned char *)&src[i],
1786 						&auth_tok_list, &new_auth_tok,
1787 						&packet_size, max_packet_size);
1788 			if (rc) {
1789 				ecryptfs_printk(KERN_ERR, "Error parsing "
1790 						"tag 3 packet\n");
1791 				rc = -EIO;
1792 				goto out_wipe_list;
1793 			}
1794 			i += packet_size;
1795 			rc = parse_tag_11_packet((unsigned char *)&src[i],
1796 						 sig_tmp_space,
1797 						 ECRYPTFS_SIG_SIZE,
1798 						 &tag_11_contents_size,
1799 						 &tag_11_packet_size,
1800 						 max_packet_size);
1801 			if (rc) {
1802 				ecryptfs_printk(KERN_ERR, "No valid "
1803 						"(ecryptfs-specific) literal "
1804 						"packet containing "
1805 						"authentication token "
1806 						"signature found after "
1807 						"tag 3 packet\n");
1808 				rc = -EIO;
1809 				goto out_wipe_list;
1810 			}
1811 			i += tag_11_packet_size;
1812 			if (ECRYPTFS_SIG_SIZE != tag_11_contents_size) {
1813 				ecryptfs_printk(KERN_ERR, "Expected "
1814 						"signature of size [%d]; "
1815 						"read size [%zd]\n",
1816 						ECRYPTFS_SIG_SIZE,
1817 						tag_11_contents_size);
1818 				rc = -EIO;
1819 				goto out_wipe_list;
1820 			}
1821 			ecryptfs_to_hex(new_auth_tok->token.password.signature,
1822 					sig_tmp_space, tag_11_contents_size);
1823 			new_auth_tok->token.password.signature[
1824 				ECRYPTFS_PASSWORD_SIG_SIZE] = '\0';
1825 			crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
1826 			break;
1827 		case ECRYPTFS_TAG_1_PACKET_TYPE:
1828 			rc = parse_tag_1_packet(crypt_stat,
1829 						(unsigned char *)&src[i],
1830 						&auth_tok_list, &new_auth_tok,
1831 						&packet_size, max_packet_size);
1832 			if (rc) {
1833 				ecryptfs_printk(KERN_ERR, "Error parsing "
1834 						"tag 1 packet\n");
1835 				rc = -EIO;
1836 				goto out_wipe_list;
1837 			}
1838 			i += packet_size;
1839 			crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
1840 			break;
1841 		case ECRYPTFS_TAG_11_PACKET_TYPE:
1842 			ecryptfs_printk(KERN_WARNING, "Invalid packet set "
1843 					"(Tag 11 not allowed by itself)\n");
1844 			rc = -EIO;
1845 			goto out_wipe_list;
1846 		default:
1847 			ecryptfs_printk(KERN_DEBUG, "No packet at offset [%zd] "
1848 					"of the file header; hex value of "
1849 					"character is [0x%.2x]\n", i, src[i]);
1850 			next_packet_is_auth_tok_packet = 0;
1851 		}
1852 	}
1853 	if (list_empty(&auth_tok_list)) {
1854 		printk(KERN_ERR "The lower file appears to be a non-encrypted "
1855 		       "eCryptfs file; this is not supported in this version "
1856 		       "of the eCryptfs kernel module\n");
1857 		rc = -EINVAL;
1858 		goto out;
1859 	}
1860 	/* auth_tok_list contains the set of authentication tokens
1861 	 * parsed from the metadata. We need to find a matching
1862 	 * authentication token that has the secret component(s)
1863 	 * necessary to decrypt the EFEK in the auth_tok parsed from
1864 	 * the metadata. There may be several potential matches, but
1865 	 * just one will be sufficient to decrypt to get the FEK. */
1866 find_next_matching_auth_tok:
1867 	found_auth_tok = 0;
1868 	list_for_each_entry(auth_tok_list_item, &auth_tok_list, list) {
1869 		candidate_auth_tok = &auth_tok_list_item->auth_tok;
1870 		if (unlikely(ecryptfs_verbosity > 0)) {
1871 			ecryptfs_printk(KERN_DEBUG,
1872 					"Considering candidate auth tok:\n");
1873 			ecryptfs_dump_auth_tok(candidate_auth_tok);
1874 		}
1875 		rc = ecryptfs_get_auth_tok_sig(&candidate_auth_tok_sig,
1876 					       candidate_auth_tok);
1877 		if (rc) {
1878 			printk(KERN_ERR
1879 			       "Unrecognized candidate auth tok type: [%d]\n",
1880 			       candidate_auth_tok->token_type);
1881 			rc = -EINVAL;
1882 			goto out_wipe_list;
1883 		}
1884 		rc = ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
1885 					       &matching_auth_tok,
1886 					       crypt_stat->mount_crypt_stat,
1887 					       candidate_auth_tok_sig);
1888 		if (!rc) {
1889 			found_auth_tok = 1;
1890 			goto found_matching_auth_tok;
1891 		}
1892 	}
1893 	if (!found_auth_tok) {
1894 		ecryptfs_printk(KERN_ERR, "Could not find a usable "
1895 				"authentication token\n");
1896 		rc = -EIO;
1897 		goto out_wipe_list;
1898 	}
1899 found_matching_auth_tok:
1900 	if (candidate_auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
1901 		memcpy(&(candidate_auth_tok->token.private_key),
1902 		       &(matching_auth_tok->token.private_key),
1903 		       sizeof(struct ecryptfs_private_key));
1904 		up_write(&(auth_tok_key->sem));
1905 		key_put(auth_tok_key);
1906 		rc = decrypt_pki_encrypted_session_key(candidate_auth_tok,
1907 						       crypt_stat);
1908 	} else if (candidate_auth_tok->token_type == ECRYPTFS_PASSWORD) {
1909 		memcpy(&(candidate_auth_tok->token.password),
1910 		       &(matching_auth_tok->token.password),
1911 		       sizeof(struct ecryptfs_password));
1912 		up_write(&(auth_tok_key->sem));
1913 		key_put(auth_tok_key);
1914 		rc = decrypt_passphrase_encrypted_session_key(
1915 			candidate_auth_tok, crypt_stat);
1916 	} else {
1917 		up_write(&(auth_tok_key->sem));
1918 		key_put(auth_tok_key);
1919 		rc = -EINVAL;
1920 	}
1921 	if (rc) {
1922 		struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;
1923 
1924 		ecryptfs_printk(KERN_WARNING, "Error decrypting the "
1925 				"session key for authentication token with sig "
1926 				"[%.*s]; rc = [%d]. Removing auth tok "
1927 				"candidate from the list and searching for "
1928 				"the next match.\n", ECRYPTFS_SIG_SIZE_HEX,
1929 				candidate_auth_tok_sig,	rc);
1930 		list_for_each_entry_safe(auth_tok_list_item,
1931 					 auth_tok_list_item_tmp,
1932 					 &auth_tok_list, list) {
1933 			if (candidate_auth_tok
1934 			    == &auth_tok_list_item->auth_tok) {
1935 				list_del(&auth_tok_list_item->list);
1936 				kmem_cache_free(
1937 					ecryptfs_auth_tok_list_item_cache,
1938 					auth_tok_list_item);
1939 				goto find_next_matching_auth_tok;
1940 			}
1941 		}
1942 		BUG();
1943 	}
1944 	rc = ecryptfs_compute_root_iv(crypt_stat);
1945 	if (rc) {
1946 		ecryptfs_printk(KERN_ERR, "Error computing "
1947 				"the root IV\n");
1948 		goto out_wipe_list;
1949 	}
1950 	rc = ecryptfs_init_crypt_ctx(crypt_stat);
1951 	if (rc) {
1952 		ecryptfs_printk(KERN_ERR, "Error initializing crypto "
1953 				"context for cipher [%s]; rc = [%d]\n",
1954 				crypt_stat->cipher, rc);
1955 	}
1956 out_wipe_list:
1957 	wipe_auth_tok_list(&auth_tok_list);
1958 out:
1959 	return rc;
1960 }
1961 
1962 static int
pki_encrypt_session_key(struct key * auth_tok_key,struct ecryptfs_auth_tok * auth_tok,struct ecryptfs_crypt_stat * crypt_stat,struct ecryptfs_key_record * key_rec)1963 pki_encrypt_session_key(struct key *auth_tok_key,
1964 			struct ecryptfs_auth_tok *auth_tok,
1965 			struct ecryptfs_crypt_stat *crypt_stat,
1966 			struct ecryptfs_key_record *key_rec)
1967 {
1968 	struct ecryptfs_msg_ctx *msg_ctx = NULL;
1969 	char *payload = NULL;
1970 	size_t payload_len = 0;
1971 	struct ecryptfs_message *msg;
1972 	int rc;
1973 
1974 	rc = write_tag_66_packet(auth_tok->token.private_key.signature,
1975 				 ecryptfs_code_for_cipher_string(
1976 					 crypt_stat->cipher,
1977 					 crypt_stat->key_size),
1978 				 crypt_stat, &payload, &payload_len);
1979 	up_write(&(auth_tok_key->sem));
1980 	key_put(auth_tok_key);
1981 	if (rc) {
1982 		ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet\n");
1983 		goto out;
1984 	}
1985 	rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);
1986 	if (rc) {
1987 		ecryptfs_printk(KERN_ERR, "Error sending message to "
1988 				"ecryptfsd: %d\n", rc);
1989 		goto out;
1990 	}
1991 	rc = ecryptfs_wait_for_response(msg_ctx, &msg);
1992 	if (rc) {
1993 		ecryptfs_printk(KERN_ERR, "Failed to receive tag 67 packet "
1994 				"from the user space daemon\n");
1995 		rc = -EIO;
1996 		goto out;
1997 	}
1998 	rc = parse_tag_67_packet(key_rec, msg);
1999 	if (rc)
2000 		ecryptfs_printk(KERN_ERR, "Error parsing tag 67 packet\n");
2001 	kfree(msg);
2002 out:
2003 	kfree(payload);
2004 	return rc;
2005 }
2006 /**
2007  * write_tag_1_packet - Write an RFC2440-compatible tag 1 (public key) packet
2008  * @dest: Buffer into which to write the packet
2009  * @remaining_bytes: Maximum number of bytes that can be writtn
2010  * @auth_tok_key: The authentication token key to unlock and put when done with
2011  *                @auth_tok
2012  * @auth_tok: The authentication token used for generating the tag 1 packet
2013  * @crypt_stat: The cryptographic context
2014  * @key_rec: The key record struct for the tag 1 packet
2015  * @packet_size: This function will write the number of bytes that end
2016  *               up constituting the packet; set to zero on error
2017  *
2018  * Returns zero on success; non-zero on error.
2019  */
2020 static int
write_tag_1_packet(char * dest,size_t * remaining_bytes,struct key * auth_tok_key,struct ecryptfs_auth_tok * auth_tok,struct ecryptfs_crypt_stat * crypt_stat,struct ecryptfs_key_record * key_rec,size_t * packet_size)2021 write_tag_1_packet(char *dest, size_t *remaining_bytes,
2022 		   struct key *auth_tok_key, struct ecryptfs_auth_tok *auth_tok,
2023 		   struct ecryptfs_crypt_stat *crypt_stat,
2024 		   struct ecryptfs_key_record *key_rec, size_t *packet_size)
2025 {
2026 	size_t i;
2027 	size_t encrypted_session_key_valid = 0;
2028 	size_t packet_size_length;
2029 	size_t max_packet_size;
2030 	int rc = 0;
2031 
2032 	(*packet_size) = 0;
2033 	ecryptfs_from_hex(key_rec->sig, auth_tok->token.private_key.signature,
2034 			  ECRYPTFS_SIG_SIZE);
2035 	encrypted_session_key_valid = 0;
2036 	for (i = 0; i < crypt_stat->key_size; i++)
2037 		encrypted_session_key_valid |=
2038 			auth_tok->session_key.encrypted_key[i];
2039 	if (encrypted_session_key_valid) {
2040 		memcpy(key_rec->enc_key,
2041 		       auth_tok->session_key.encrypted_key,
2042 		       auth_tok->session_key.encrypted_key_size);
2043 		up_write(&(auth_tok_key->sem));
2044 		key_put(auth_tok_key);
2045 		goto encrypted_session_key_set;
2046 	}
2047 	if (auth_tok->session_key.encrypted_key_size == 0)
2048 		auth_tok->session_key.encrypted_key_size =
2049 			auth_tok->token.private_key.key_size;
2050 	rc = pki_encrypt_session_key(auth_tok_key, auth_tok, crypt_stat,
2051 				     key_rec);
2052 	if (rc) {
2053 		printk(KERN_ERR "Failed to encrypt session key via a key "
2054 		       "module; rc = [%d]\n", rc);
2055 		goto out;
2056 	}
2057 	if (ecryptfs_verbosity > 0) {
2058 		ecryptfs_printk(KERN_DEBUG, "Encrypted key:\n");
2059 		ecryptfs_dump_hex(key_rec->enc_key, key_rec->enc_key_size);
2060 	}
2061 encrypted_session_key_set:
2062 	/* This format is inspired by OpenPGP; see RFC 2440
2063 	 * packet tag 1 */
2064 	max_packet_size = (1                         /* Tag 1 identifier */
2065 			   + 3                       /* Max Tag 1 packet size */
2066 			   + 1                       /* Version */
2067 			   + ECRYPTFS_SIG_SIZE       /* Key identifier */
2068 			   + 1                       /* Cipher identifier */
2069 			   + key_rec->enc_key_size); /* Encrypted key size */
2070 	if (max_packet_size > (*remaining_bytes)) {
2071 		printk(KERN_ERR "Packet length larger than maximum allowable; "
2072 		       "need up to [%td] bytes, but there are only [%td] "
2073 		       "available\n", max_packet_size, (*remaining_bytes));
2074 		rc = -EINVAL;
2075 		goto out;
2076 	}
2077 	dest[(*packet_size)++] = ECRYPTFS_TAG_1_PACKET_TYPE;
2078 	rc = ecryptfs_write_packet_length(&dest[(*packet_size)],
2079 					  (max_packet_size - 4),
2080 					  &packet_size_length);
2081 	if (rc) {
2082 		ecryptfs_printk(KERN_ERR, "Error generating tag 1 packet "
2083 				"header; cannot generate packet length\n");
2084 		goto out;
2085 	}
2086 	(*packet_size) += packet_size_length;
2087 	dest[(*packet_size)++] = 0x03; /* version 3 */
2088 	memcpy(&dest[(*packet_size)], key_rec->sig, ECRYPTFS_SIG_SIZE);
2089 	(*packet_size) += ECRYPTFS_SIG_SIZE;
2090 	dest[(*packet_size)++] = RFC2440_CIPHER_RSA;
2091 	memcpy(&dest[(*packet_size)], key_rec->enc_key,
2092 	       key_rec->enc_key_size);
2093 	(*packet_size) += key_rec->enc_key_size;
2094 out:
2095 	if (rc)
2096 		(*packet_size) = 0;
2097 	else
2098 		(*remaining_bytes) -= (*packet_size);
2099 	return rc;
2100 }
2101 
2102 /**
2103  * write_tag_11_packet
2104  * @dest: Target into which Tag 11 packet is to be written
2105  * @remaining_bytes: Maximum packet length
2106  * @contents: Byte array of contents to copy in
2107  * @contents_length: Number of bytes in contents
2108  * @packet_length: Length of the Tag 11 packet written; zero on error
2109  *
2110  * Returns zero on success; non-zero on error.
2111  */
2112 static int
write_tag_11_packet(char * dest,size_t * remaining_bytes,char * contents,size_t contents_length,size_t * packet_length)2113 write_tag_11_packet(char *dest, size_t *remaining_bytes, char *contents,
2114 		    size_t contents_length, size_t *packet_length)
2115 {
2116 	size_t packet_size_length;
2117 	size_t max_packet_size;
2118 	int rc = 0;
2119 
2120 	(*packet_length) = 0;
2121 	/* This format is inspired by OpenPGP; see RFC 2440
2122 	 * packet tag 11 */
2123 	max_packet_size = (1                   /* Tag 11 identifier */
2124 			   + 3                 /* Max Tag 11 packet size */
2125 			   + 1                 /* Binary format specifier */
2126 			   + 1                 /* Filename length */
2127 			   + 8                 /* Filename ("_CONSOLE") */
2128 			   + 4                 /* Modification date */
2129 			   + contents_length); /* Literal data */
2130 	if (max_packet_size > (*remaining_bytes)) {
2131 		printk(KERN_ERR "Packet length larger than maximum allowable; "
2132 		       "need up to [%td] bytes, but there are only [%td] "
2133 		       "available\n", max_packet_size, (*remaining_bytes));
2134 		rc = -EINVAL;
2135 		goto out;
2136 	}
2137 	dest[(*packet_length)++] = ECRYPTFS_TAG_11_PACKET_TYPE;
2138 	rc = ecryptfs_write_packet_length(&dest[(*packet_length)],
2139 					  (max_packet_size - 4),
2140 					  &packet_size_length);
2141 	if (rc) {
2142 		printk(KERN_ERR "Error generating tag 11 packet header; cannot "
2143 		       "generate packet length. rc = [%d]\n", rc);
2144 		goto out;
2145 	}
2146 	(*packet_length) += packet_size_length;
2147 	dest[(*packet_length)++] = 0x62; /* binary data format specifier */
2148 	dest[(*packet_length)++] = 8;
2149 	memcpy(&dest[(*packet_length)], "_CONSOLE", 8);
2150 	(*packet_length) += 8;
2151 	memset(&dest[(*packet_length)], 0x00, 4);
2152 	(*packet_length) += 4;
2153 	memcpy(&dest[(*packet_length)], contents, contents_length);
2154 	(*packet_length) += contents_length;
2155  out:
2156 	if (rc)
2157 		(*packet_length) = 0;
2158 	else
2159 		(*remaining_bytes) -= (*packet_length);
2160 	return rc;
2161 }
2162 
2163 /**
2164  * write_tag_3_packet
2165  * @dest: Buffer into which to write the packet
2166  * @remaining_bytes: Maximum number of bytes that can be written
2167  * @auth_tok: Authentication token
2168  * @crypt_stat: The cryptographic context
2169  * @key_rec: encrypted key
2170  * @packet_size: This function will write the number of bytes that end
2171  *               up constituting the packet; set to zero on error
2172  *
2173  * Returns zero on success; non-zero on error.
2174  */
2175 static int
write_tag_3_packet(char * dest,size_t * remaining_bytes,struct ecryptfs_auth_tok * auth_tok,struct ecryptfs_crypt_stat * crypt_stat,struct ecryptfs_key_record * key_rec,size_t * packet_size)2176 write_tag_3_packet(char *dest, size_t *remaining_bytes,
2177 		   struct ecryptfs_auth_tok *auth_tok,
2178 		   struct ecryptfs_crypt_stat *crypt_stat,
2179 		   struct ecryptfs_key_record *key_rec, size_t *packet_size)
2180 {
2181 	size_t i;
2182 	size_t encrypted_session_key_valid = 0;
2183 	char session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES];
2184 	struct scatterlist dst_sg[2];
2185 	struct scatterlist src_sg[2];
2186 	struct mutex *tfm_mutex = NULL;
2187 	u8 cipher_code;
2188 	size_t packet_size_length;
2189 	size_t max_packet_size;
2190 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2191 		crypt_stat->mount_crypt_stat;
2192 	struct crypto_skcipher *tfm;
2193 	struct skcipher_request *req;
2194 	int rc = 0;
2195 
2196 	(*packet_size) = 0;
2197 	ecryptfs_from_hex(key_rec->sig, auth_tok->token.password.signature,
2198 			  ECRYPTFS_SIG_SIZE);
2199 	rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex,
2200 							crypt_stat->cipher);
2201 	if (unlikely(rc)) {
2202 		printk(KERN_ERR "Internal error whilst attempting to get "
2203 		       "tfm and mutex for cipher name [%s]; rc = [%d]\n",
2204 		       crypt_stat->cipher, rc);
2205 		goto out;
2206 	}
2207 	if (mount_crypt_stat->global_default_cipher_key_size == 0) {
2208 		printk(KERN_WARNING "No key size specified at mount; "
2209 		       "defaulting to [%d]\n",
2210 		       crypto_skcipher_max_keysize(tfm));
2211 		mount_crypt_stat->global_default_cipher_key_size =
2212 			crypto_skcipher_max_keysize(tfm);
2213 	}
2214 	if (crypt_stat->key_size == 0)
2215 		crypt_stat->key_size =
2216 			mount_crypt_stat->global_default_cipher_key_size;
2217 	if (auth_tok->session_key.encrypted_key_size == 0)
2218 		auth_tok->session_key.encrypted_key_size =
2219 			crypt_stat->key_size;
2220 	if (crypt_stat->key_size == 24
2221 	    && strcmp("aes", crypt_stat->cipher) == 0) {
2222 		memset((crypt_stat->key + 24), 0, 8);
2223 		auth_tok->session_key.encrypted_key_size = 32;
2224 	} else
2225 		auth_tok->session_key.encrypted_key_size = crypt_stat->key_size;
2226 	key_rec->enc_key_size =
2227 		auth_tok->session_key.encrypted_key_size;
2228 	encrypted_session_key_valid = 0;
2229 	for (i = 0; i < auth_tok->session_key.encrypted_key_size; i++)
2230 		encrypted_session_key_valid |=
2231 			auth_tok->session_key.encrypted_key[i];
2232 	if (encrypted_session_key_valid) {
2233 		ecryptfs_printk(KERN_DEBUG, "encrypted_session_key_valid != 0; "
2234 				"using auth_tok->session_key.encrypted_key, "
2235 				"where key_rec->enc_key_size = [%zd]\n",
2236 				key_rec->enc_key_size);
2237 		memcpy(key_rec->enc_key,
2238 		       auth_tok->session_key.encrypted_key,
2239 		       key_rec->enc_key_size);
2240 		goto encrypted_session_key_set;
2241 	}
2242 	if (auth_tok->token.password.flags &
2243 	    ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET) {
2244 		ecryptfs_printk(KERN_DEBUG, "Using previously generated "
2245 				"session key encryption key of size [%d]\n",
2246 				auth_tok->token.password.
2247 				session_key_encryption_key_bytes);
2248 		memcpy(session_key_encryption_key,
2249 		       auth_tok->token.password.session_key_encryption_key,
2250 		       crypt_stat->key_size);
2251 		ecryptfs_printk(KERN_DEBUG,
2252 				"Cached session key encryption key:\n");
2253 		if (ecryptfs_verbosity > 0)
2254 			ecryptfs_dump_hex(session_key_encryption_key, 16);
2255 	}
2256 	if (unlikely(ecryptfs_verbosity > 0)) {
2257 		ecryptfs_printk(KERN_DEBUG, "Session key encryption key:\n");
2258 		ecryptfs_dump_hex(session_key_encryption_key, 16);
2259 	}
2260 	rc = virt_to_scatterlist(crypt_stat->key, key_rec->enc_key_size,
2261 				 src_sg, 2);
2262 	if (rc < 1 || rc > 2) {
2263 		ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
2264 				"for crypt_stat session key; expected rc = 1; "
2265 				"got rc = [%d]. key_rec->enc_key_size = [%zd]\n",
2266 				rc, key_rec->enc_key_size);
2267 		rc = -ENOMEM;
2268 		goto out;
2269 	}
2270 	rc = virt_to_scatterlist(key_rec->enc_key, key_rec->enc_key_size,
2271 				 dst_sg, 2);
2272 	if (rc < 1 || rc > 2) {
2273 		ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
2274 				"for crypt_stat encrypted session key; "
2275 				"expected rc = 1; got rc = [%d]. "
2276 				"key_rec->enc_key_size = [%zd]\n", rc,
2277 				key_rec->enc_key_size);
2278 		rc = -ENOMEM;
2279 		goto out;
2280 	}
2281 	mutex_lock(tfm_mutex);
2282 	rc = crypto_skcipher_setkey(tfm, session_key_encryption_key,
2283 				    crypt_stat->key_size);
2284 	if (rc < 0) {
2285 		mutex_unlock(tfm_mutex);
2286 		ecryptfs_printk(KERN_ERR, "Error setting key for crypto "
2287 				"context; rc = [%d]\n", rc);
2288 		goto out;
2289 	}
2290 
2291 	req = skcipher_request_alloc(tfm, GFP_KERNEL);
2292 	if (!req) {
2293 		mutex_unlock(tfm_mutex);
2294 		ecryptfs_printk(KERN_ERR, "Out of kernel memory whilst "
2295 				"attempting to skcipher_request_alloc for "
2296 				"%s\n", crypto_skcipher_driver_name(tfm));
2297 		rc = -ENOMEM;
2298 		goto out;
2299 	}
2300 
2301 	skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP,
2302 				      NULL, NULL);
2303 
2304 	rc = 0;
2305 	ecryptfs_printk(KERN_DEBUG, "Encrypting [%zd] bytes of the key\n",
2306 			crypt_stat->key_size);
2307 	skcipher_request_set_crypt(req, src_sg, dst_sg,
2308 				   (*key_rec).enc_key_size, NULL);
2309 	rc = crypto_skcipher_encrypt(req);
2310 	mutex_unlock(tfm_mutex);
2311 	skcipher_request_free(req);
2312 	if (rc) {
2313 		printk(KERN_ERR "Error encrypting; rc = [%d]\n", rc);
2314 		goto out;
2315 	}
2316 	ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n");
2317 	if (ecryptfs_verbosity > 0) {
2318 		ecryptfs_printk(KERN_DEBUG, "EFEK of size [%zd]:\n",
2319 				key_rec->enc_key_size);
2320 		ecryptfs_dump_hex(key_rec->enc_key,
2321 				  key_rec->enc_key_size);
2322 	}
2323 encrypted_session_key_set:
2324 	/* This format is inspired by OpenPGP; see RFC 2440
2325 	 * packet tag 3 */
2326 	max_packet_size = (1                         /* Tag 3 identifier */
2327 			   + 3                       /* Max Tag 3 packet size */
2328 			   + 1                       /* Version */
2329 			   + 1                       /* Cipher code */
2330 			   + 1                       /* S2K specifier */
2331 			   + 1                       /* Hash identifier */
2332 			   + ECRYPTFS_SALT_SIZE      /* Salt */
2333 			   + 1                       /* Hash iterations */
2334 			   + key_rec->enc_key_size); /* Encrypted key size */
2335 	if (max_packet_size > (*remaining_bytes)) {
2336 		printk(KERN_ERR "Packet too large; need up to [%td] bytes, but "
2337 		       "there are only [%td] available\n", max_packet_size,
2338 		       (*remaining_bytes));
2339 		rc = -EINVAL;
2340 		goto out;
2341 	}
2342 	dest[(*packet_size)++] = ECRYPTFS_TAG_3_PACKET_TYPE;
2343 	/* Chop off the Tag 3 identifier(1) and Tag 3 packet size(3)
2344 	 * to get the number of octets in the actual Tag 3 packet */
2345 	rc = ecryptfs_write_packet_length(&dest[(*packet_size)],
2346 					  (max_packet_size - 4),
2347 					  &packet_size_length);
2348 	if (rc) {
2349 		printk(KERN_ERR "Error generating tag 3 packet header; cannot "
2350 		       "generate packet length. rc = [%d]\n", rc);
2351 		goto out;
2352 	}
2353 	(*packet_size) += packet_size_length;
2354 	dest[(*packet_size)++] = 0x04; /* version 4 */
2355 	/* TODO: Break from RFC2440 so that arbitrary ciphers can be
2356 	 * specified with strings */
2357 	cipher_code = ecryptfs_code_for_cipher_string(crypt_stat->cipher,
2358 						      crypt_stat->key_size);
2359 	if (cipher_code == 0) {
2360 		ecryptfs_printk(KERN_WARNING, "Unable to generate code for "
2361 				"cipher [%s]\n", crypt_stat->cipher);
2362 		rc = -EINVAL;
2363 		goto out;
2364 	}
2365 	dest[(*packet_size)++] = cipher_code;
2366 	dest[(*packet_size)++] = 0x03;	/* S2K */
2367 	dest[(*packet_size)++] = 0x01;	/* MD5 (TODO: parameterize) */
2368 	memcpy(&dest[(*packet_size)], auth_tok->token.password.salt,
2369 	       ECRYPTFS_SALT_SIZE);
2370 	(*packet_size) += ECRYPTFS_SALT_SIZE;	/* salt */
2371 	dest[(*packet_size)++] = 0x60;	/* hash iterations (65536) */
2372 	memcpy(&dest[(*packet_size)], key_rec->enc_key,
2373 	       key_rec->enc_key_size);
2374 	(*packet_size) += key_rec->enc_key_size;
2375 out:
2376 	if (rc)
2377 		(*packet_size) = 0;
2378 	else
2379 		(*remaining_bytes) -= (*packet_size);
2380 	return rc;
2381 }
2382 
2383 struct kmem_cache *ecryptfs_key_record_cache;
2384 
2385 /**
2386  * ecryptfs_generate_key_packet_set
2387  * @dest_base: Virtual address from which to write the key record set
2388  * @crypt_stat: The cryptographic context from which the
2389  *              authentication tokens will be retrieved
2390  * @ecryptfs_dentry: The dentry, used to retrieve the mount crypt stat
2391  *                   for the global parameters
2392  * @len: The amount written
2393  * @max: The maximum amount of data allowed to be written
2394  *
2395  * Generates a key packet set and writes it to the virtual address
2396  * passed in.
2397  *
2398  * Returns zero on success; non-zero on error.
2399  */
2400 int
ecryptfs_generate_key_packet_set(char * dest_base,struct ecryptfs_crypt_stat * crypt_stat,struct dentry * ecryptfs_dentry,size_t * len,size_t max)2401 ecryptfs_generate_key_packet_set(char *dest_base,
2402 				 struct ecryptfs_crypt_stat *crypt_stat,
2403 				 struct dentry *ecryptfs_dentry, size_t *len,
2404 				 size_t max)
2405 {
2406 	struct ecryptfs_auth_tok *auth_tok;
2407 	struct key *auth_tok_key = NULL;
2408 	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2409 		&ecryptfs_superblock_to_private(
2410 			ecryptfs_dentry->d_sb)->mount_crypt_stat;
2411 	size_t written;
2412 	struct ecryptfs_key_record *key_rec;
2413 	struct ecryptfs_key_sig *key_sig;
2414 	int rc = 0;
2415 
2416 	(*len) = 0;
2417 	mutex_lock(&crypt_stat->keysig_list_mutex);
2418 	key_rec = kmem_cache_alloc(ecryptfs_key_record_cache, GFP_KERNEL);
2419 	if (!key_rec) {
2420 		rc = -ENOMEM;
2421 		goto out;
2422 	}
2423 	list_for_each_entry(key_sig, &crypt_stat->keysig_list,
2424 			    crypt_stat_list) {
2425 		memset(key_rec, 0, sizeof(*key_rec));
2426 		rc = ecryptfs_find_global_auth_tok_for_sig(&auth_tok_key,
2427 							   &auth_tok,
2428 							   mount_crypt_stat,
2429 							   key_sig->keysig);
2430 		if (rc) {
2431 			printk(KERN_WARNING "Unable to retrieve auth tok with "
2432 			       "sig = [%s]\n", key_sig->keysig);
2433 			rc = process_find_global_auth_tok_for_sig_err(rc);
2434 			goto out_free;
2435 		}
2436 		if (auth_tok->token_type == ECRYPTFS_PASSWORD) {
2437 			rc = write_tag_3_packet((dest_base + (*len)),
2438 						&max, auth_tok,
2439 						crypt_stat, key_rec,
2440 						&written);
2441 			up_write(&(auth_tok_key->sem));
2442 			key_put(auth_tok_key);
2443 			if (rc) {
2444 				ecryptfs_printk(KERN_WARNING, "Error "
2445 						"writing tag 3 packet\n");
2446 				goto out_free;
2447 			}
2448 			(*len) += written;
2449 			/* Write auth tok signature packet */
2450 			rc = write_tag_11_packet((dest_base + (*len)), &max,
2451 						 key_rec->sig,
2452 						 ECRYPTFS_SIG_SIZE, &written);
2453 			if (rc) {
2454 				ecryptfs_printk(KERN_ERR, "Error writing "
2455 						"auth tok signature packet\n");
2456 				goto out_free;
2457 			}
2458 			(*len) += written;
2459 		} else if (auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
2460 			rc = write_tag_1_packet(dest_base + (*len), &max,
2461 						auth_tok_key, auth_tok,
2462 						crypt_stat, key_rec, &written);
2463 			if (rc) {
2464 				ecryptfs_printk(KERN_WARNING, "Error "
2465 						"writing tag 1 packet\n");
2466 				goto out_free;
2467 			}
2468 			(*len) += written;
2469 		} else {
2470 			up_write(&(auth_tok_key->sem));
2471 			key_put(auth_tok_key);
2472 			ecryptfs_printk(KERN_WARNING, "Unsupported "
2473 					"authentication token type\n");
2474 			rc = -EINVAL;
2475 			goto out_free;
2476 		}
2477 	}
2478 	if (likely(max > 0)) {
2479 		dest_base[(*len)] = 0x00;
2480 	} else {
2481 		ecryptfs_printk(KERN_ERR, "Error writing boundary byte\n");
2482 		rc = -EIO;
2483 	}
2484 out_free:
2485 	kmem_cache_free(ecryptfs_key_record_cache, key_rec);
2486 out:
2487 	if (rc)
2488 		(*len) = 0;
2489 	mutex_unlock(&crypt_stat->keysig_list_mutex);
2490 	return rc;
2491 }
2492 
2493 struct kmem_cache *ecryptfs_key_sig_cache;
2494 
ecryptfs_add_keysig(struct ecryptfs_crypt_stat * crypt_stat,char * sig)2495 int ecryptfs_add_keysig(struct ecryptfs_crypt_stat *crypt_stat, char *sig)
2496 {
2497 	struct ecryptfs_key_sig *new_key_sig;
2498 
2499 	new_key_sig = kmem_cache_alloc(ecryptfs_key_sig_cache, GFP_KERNEL);
2500 	if (!new_key_sig)
2501 		return -ENOMEM;
2502 
2503 	memcpy(new_key_sig->keysig, sig, ECRYPTFS_SIG_SIZE_HEX);
2504 	new_key_sig->keysig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
2505 	/* Caller must hold keysig_list_mutex */
2506 	list_add(&new_key_sig->crypt_stat_list, &crypt_stat->keysig_list);
2507 
2508 	return 0;
2509 }
2510 
2511 struct kmem_cache *ecryptfs_global_auth_tok_cache;
2512 
2513 int
ecryptfs_add_global_auth_tok(struct ecryptfs_mount_crypt_stat * mount_crypt_stat,char * sig,u32 global_auth_tok_flags)2514 ecryptfs_add_global_auth_tok(struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
2515 			     char *sig, u32 global_auth_tok_flags)
2516 {
2517 	struct ecryptfs_global_auth_tok *new_auth_tok;
2518 
2519 	new_auth_tok = kmem_cache_zalloc(ecryptfs_global_auth_tok_cache,
2520 					GFP_KERNEL);
2521 	if (!new_auth_tok)
2522 		return -ENOMEM;
2523 
2524 	memcpy(new_auth_tok->sig, sig, ECRYPTFS_SIG_SIZE_HEX);
2525 	new_auth_tok->flags = global_auth_tok_flags;
2526 	new_auth_tok->sig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
2527 	mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
2528 	list_add(&new_auth_tok->mount_crypt_stat_list,
2529 		 &mount_crypt_stat->global_auth_tok_list);
2530 	mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
2531 	return 0;
2532 }
2533 
2534