Merge tag 'xfs-4.15-merge-2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux
[muen/linux.git] / fs / ecryptfs / keystore.c
1 /**
2  * eCryptfs: Linux filesystem encryption layer
3  * In-kernel key management code.  Includes functions to parse and
4  * write authentication token-related packets with the underlying
5  * file.
6  *
7  * Copyright (C) 2004-2006 International Business Machines Corp.
8  *   Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
9  *              Michael C. Thompson <mcthomps@us.ibm.com>
10  *              Trevor S. Highland <trevor.highland@gmail.com>
11  *
12  * This program is free software; you can redistribute it and/or
13  * modify it under the terms of the GNU General Public License as
14  * published by the Free Software Foundation; either version 2 of the
15  * License, or (at your option) any later version.
16  *
17  * This program is distributed in the hope that it will be useful, but
18  * WITHOUT ANY WARRANTY; without even the implied warranty of
19  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
20  * General Public License for more details.
21  *
22  * You should have received a copy of the GNU General Public License
23  * along with this program; if not, write to the Free Software
24  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
25  * 02111-1307, USA.
26  */
27
28 #include <crypto/hash.h>
29 #include <crypto/skcipher.h>
30 #include <linux/string.h>
31 #include <linux/pagemap.h>
32 #include <linux/key.h>
33 #include <linux/random.h>
34 #include <linux/scatterlist.h>
35 #include <linux/slab.h>
36 #include "ecryptfs_kernel.h"
37
38 /**
39  * request_key returned an error instead of a valid key address;
40  * determine the type of error, make appropriate log entries, and
41  * return an error code.
42  */
43 static int process_request_key_err(long err_code)
44 {
45         int rc = 0;
46
47         switch (err_code) {
48         case -ENOKEY:
49                 ecryptfs_printk(KERN_WARNING, "No key\n");
50                 rc = -ENOENT;
51                 break;
52         case -EKEYEXPIRED:
53                 ecryptfs_printk(KERN_WARNING, "Key expired\n");
54                 rc = -ETIME;
55                 break;
56         case -EKEYREVOKED:
57                 ecryptfs_printk(KERN_WARNING, "Key revoked\n");
58                 rc = -EINVAL;
59                 break;
60         default:
61                 ecryptfs_printk(KERN_WARNING, "Unknown error code: "
62                                 "[0x%.16lx]\n", err_code);
63                 rc = -EINVAL;
64         }
65         return rc;
66 }
67
68 static int process_find_global_auth_tok_for_sig_err(int err_code)
69 {
70         int rc = err_code;
71
72         switch (err_code) {
73         case -ENOENT:
74                 ecryptfs_printk(KERN_WARNING, "Missing auth tok\n");
75                 break;
76         case -EINVAL:
77                 ecryptfs_printk(KERN_WARNING, "Invalid auth tok\n");
78                 break;
79         default:
80                 rc = process_request_key_err(err_code);
81                 break;
82         }
83         return rc;
84 }
85
86 /**
87  * ecryptfs_parse_packet_length
88  * @data: Pointer to memory containing length at offset
89  * @size: This function writes the decoded size to this memory
90  *        address; zero on error
91  * @length_size: The number of bytes occupied by the encoded length
92  *
93  * Returns zero on success; non-zero on error
94  */
95 int ecryptfs_parse_packet_length(unsigned char *data, size_t *size,
96                                  size_t *length_size)
97 {
98         int rc = 0;
99
100         (*length_size) = 0;
101         (*size) = 0;
102         if (data[0] < 192) {
103                 /* One-byte length */
104                 (*size) = data[0];
105                 (*length_size) = 1;
106         } else if (data[0] < 224) {
107                 /* Two-byte length */
108                 (*size) = (data[0] - 192) * 256;
109                 (*size) += data[1] + 192;
110                 (*length_size) = 2;
111         } else if (data[0] == 255) {
112                 /* If support is added, adjust ECRYPTFS_MAX_PKT_LEN_SIZE */
113                 ecryptfs_printk(KERN_ERR, "Five-byte packet length not "
114                                 "supported\n");
115                 rc = -EINVAL;
116                 goto out;
117         } else {
118                 ecryptfs_printk(KERN_ERR, "Error parsing packet length\n");
119                 rc = -EINVAL;
120                 goto out;
121         }
122 out:
123         return rc;
124 }
125
126 /**
127  * ecryptfs_write_packet_length
128  * @dest: The byte array target into which to write the length. Must
129  *        have at least ECRYPTFS_MAX_PKT_LEN_SIZE bytes allocated.
130  * @size: The length to write.
131  * @packet_size_length: The number of bytes used to encode the packet
132  *                      length is written to this address.
133  *
134  * Returns zero on success; non-zero on error.
135  */
136 int ecryptfs_write_packet_length(char *dest, size_t size,
137                                  size_t *packet_size_length)
138 {
139         int rc = 0;
140
141         if (size < 192) {
142                 dest[0] = size;
143                 (*packet_size_length) = 1;
144         } else if (size < 65536) {
145                 dest[0] = (((size - 192) / 256) + 192);
146                 dest[1] = ((size - 192) % 256);
147                 (*packet_size_length) = 2;
148         } else {
149                 /* If support is added, adjust ECRYPTFS_MAX_PKT_LEN_SIZE */
150                 rc = -EINVAL;
151                 ecryptfs_printk(KERN_WARNING,
152                                 "Unsupported packet size: [%zd]\n", size);
153         }
154         return rc;
155 }
156
157 static int
158 write_tag_64_packet(char *signature, struct ecryptfs_session_key *session_key,
159                     char **packet, size_t *packet_len)
160 {
161         size_t i = 0;
162         size_t data_len;
163         size_t packet_size_len;
164         char *message;
165         int rc;
166
167         /*
168          *              ***** TAG 64 Packet Format *****
169          *    | Content Type                       | 1 byte       |
170          *    | Key Identifier Size                | 1 or 2 bytes |
171          *    | Key Identifier                     | arbitrary    |
172          *    | Encrypted File Encryption Key Size | 1 or 2 bytes |
173          *    | Encrypted File Encryption Key      | arbitrary    |
174          */
175         data_len = (5 + ECRYPTFS_SIG_SIZE_HEX
176                     + session_key->encrypted_key_size);
177         *packet = kmalloc(data_len, GFP_KERNEL);
178         message = *packet;
179         if (!message) {
180                 ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
181                 rc = -ENOMEM;
182                 goto out;
183         }
184         message[i++] = ECRYPTFS_TAG_64_PACKET_TYPE;
185         rc = ecryptfs_write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
186                                           &packet_size_len);
187         if (rc) {
188                 ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
189                                 "header; cannot generate packet length\n");
190                 goto out;
191         }
192         i += packet_size_len;
193         memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
194         i += ECRYPTFS_SIG_SIZE_HEX;
195         rc = ecryptfs_write_packet_length(&message[i],
196                                           session_key->encrypted_key_size,
197                                           &packet_size_len);
198         if (rc) {
199                 ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
200                                 "header; cannot generate packet length\n");
201                 goto out;
202         }
203         i += packet_size_len;
204         memcpy(&message[i], session_key->encrypted_key,
205                session_key->encrypted_key_size);
206         i += session_key->encrypted_key_size;
207         *packet_len = i;
208 out:
209         return rc;
210 }
211
212 static int
213 parse_tag_65_packet(struct ecryptfs_session_key *session_key, u8 *cipher_code,
214                     struct ecryptfs_message *msg)
215 {
216         size_t i = 0;
217         char *data;
218         size_t data_len;
219         size_t m_size;
220         size_t message_len;
221         u16 checksum = 0;
222         u16 expected_checksum = 0;
223         int rc;
224
225         /*
226          *              ***** TAG 65 Packet Format *****
227          *         | Content Type             | 1 byte       |
228          *         | Status Indicator         | 1 byte       |
229          *         | File Encryption Key Size | 1 or 2 bytes |
230          *         | File Encryption Key      | arbitrary    |
231          */
232         message_len = msg->data_len;
233         data = msg->data;
234         if (message_len < 4) {
235                 rc = -EIO;
236                 goto out;
237         }
238         if (data[i++] != ECRYPTFS_TAG_65_PACKET_TYPE) {
239                 ecryptfs_printk(KERN_ERR, "Type should be ECRYPTFS_TAG_65\n");
240                 rc = -EIO;
241                 goto out;
242         }
243         if (data[i++]) {
244                 ecryptfs_printk(KERN_ERR, "Status indicator has non-zero value "
245                                 "[%d]\n", data[i-1]);
246                 rc = -EIO;
247                 goto out;
248         }
249         rc = ecryptfs_parse_packet_length(&data[i], &m_size, &data_len);
250         if (rc) {
251                 ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
252                                 "rc = [%d]\n", rc);
253                 goto out;
254         }
255         i += data_len;
256         if (message_len < (i + m_size)) {
257                 ecryptfs_printk(KERN_ERR, "The message received from ecryptfsd "
258                                 "is shorter than expected\n");
259                 rc = -EIO;
260                 goto out;
261         }
262         if (m_size < 3) {
263                 ecryptfs_printk(KERN_ERR,
264                                 "The decrypted key is not long enough to "
265                                 "include a cipher code and checksum\n");
266                 rc = -EIO;
267                 goto out;
268         }
269         *cipher_code = data[i++];
270         /* The decrypted key includes 1 byte cipher code and 2 byte checksum */
271         session_key->decrypted_key_size = m_size - 3;
272         if (session_key->decrypted_key_size > ECRYPTFS_MAX_KEY_BYTES) {
273                 ecryptfs_printk(KERN_ERR, "key_size [%d] larger than "
274                                 "the maximum key size [%d]\n",
275                                 session_key->decrypted_key_size,
276                                 ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
277                 rc = -EIO;
278                 goto out;
279         }
280         memcpy(session_key->decrypted_key, &data[i],
281                session_key->decrypted_key_size);
282         i += session_key->decrypted_key_size;
283         expected_checksum += (unsigned char)(data[i++]) << 8;
284         expected_checksum += (unsigned char)(data[i++]);
285         for (i = 0; i < session_key->decrypted_key_size; i++)
286                 checksum += session_key->decrypted_key[i];
287         if (expected_checksum != checksum) {
288                 ecryptfs_printk(KERN_ERR, "Invalid checksum for file "
289                                 "encryption  key; expected [%x]; calculated "
290                                 "[%x]\n", expected_checksum, checksum);
291                 rc = -EIO;
292         }
293 out:
294         return rc;
295 }
296
297
298 static int
299 write_tag_66_packet(char *signature, u8 cipher_code,
300                     struct ecryptfs_crypt_stat *crypt_stat, char **packet,
301                     size_t *packet_len)
302 {
303         size_t i = 0;
304         size_t j;
305         size_t data_len;
306         size_t checksum = 0;
307         size_t packet_size_len;
308         char *message;
309         int rc;
310
311         /*
312          *              ***** TAG 66 Packet Format *****
313          *         | Content Type             | 1 byte       |
314          *         | Key Identifier Size      | 1 or 2 bytes |
315          *         | Key Identifier           | arbitrary    |
316          *         | File Encryption Key Size | 1 or 2 bytes |
317          *         | File Encryption Key      | arbitrary    |
318          */
319         data_len = (5 + ECRYPTFS_SIG_SIZE_HEX + crypt_stat->key_size);
320         *packet = kmalloc(data_len, GFP_KERNEL);
321         message = *packet;
322         if (!message) {
323                 ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
324                 rc = -ENOMEM;
325                 goto out;
326         }
327         message[i++] = ECRYPTFS_TAG_66_PACKET_TYPE;
328         rc = ecryptfs_write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
329                                           &packet_size_len);
330         if (rc) {
331                 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
332                                 "header; cannot generate packet length\n");
333                 goto out;
334         }
335         i += packet_size_len;
336         memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
337         i += ECRYPTFS_SIG_SIZE_HEX;
338         /* The encrypted key includes 1 byte cipher code and 2 byte checksum */
339         rc = ecryptfs_write_packet_length(&message[i], crypt_stat->key_size + 3,
340                                           &packet_size_len);
341         if (rc) {
342                 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
343                                 "header; cannot generate packet length\n");
344                 goto out;
345         }
346         i += packet_size_len;
347         message[i++] = cipher_code;
348         memcpy(&message[i], crypt_stat->key, crypt_stat->key_size);
349         i += crypt_stat->key_size;
350         for (j = 0; j < crypt_stat->key_size; j++)
351                 checksum += crypt_stat->key[j];
352         message[i++] = (checksum / 256) % 256;
353         message[i++] = (checksum % 256);
354         *packet_len = i;
355 out:
356         return rc;
357 }
358
359 static int
360 parse_tag_67_packet(struct ecryptfs_key_record *key_rec,
361                     struct ecryptfs_message *msg)
362 {
363         size_t i = 0;
364         char *data;
365         size_t data_len;
366         size_t message_len;
367         int rc;
368
369         /*
370          *              ***** TAG 65 Packet Format *****
371          *    | Content Type                       | 1 byte       |
372          *    | Status Indicator                   | 1 byte       |
373          *    | Encrypted File Encryption Key Size | 1 or 2 bytes |
374          *    | Encrypted File Encryption Key      | arbitrary    |
375          */
376         message_len = msg->data_len;
377         data = msg->data;
378         /* verify that everything through the encrypted FEK size is present */
379         if (message_len < 4) {
380                 rc = -EIO;
381                 printk(KERN_ERR "%s: message_len is [%zd]; minimum acceptable "
382                        "message length is [%d]\n", __func__, message_len, 4);
383                 goto out;
384         }
385         if (data[i++] != ECRYPTFS_TAG_67_PACKET_TYPE) {
386                 rc = -EIO;
387                 printk(KERN_ERR "%s: Type should be ECRYPTFS_TAG_67\n",
388                        __func__);
389                 goto out;
390         }
391         if (data[i++]) {
392                 rc = -EIO;
393                 printk(KERN_ERR "%s: Status indicator has non zero "
394                        "value [%d]\n", __func__, data[i-1]);
395
396                 goto out;
397         }
398         rc = ecryptfs_parse_packet_length(&data[i], &key_rec->enc_key_size,
399                                           &data_len);
400         if (rc) {
401                 ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
402                                 "rc = [%d]\n", rc);
403                 goto out;
404         }
405         i += data_len;
406         if (message_len < (i + key_rec->enc_key_size)) {
407                 rc = -EIO;
408                 printk(KERN_ERR "%s: message_len [%zd]; max len is [%zd]\n",
409                        __func__, message_len, (i + key_rec->enc_key_size));
410                 goto out;
411         }
412         if (key_rec->enc_key_size > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
413                 rc = -EIO;
414                 printk(KERN_ERR "%s: Encrypted key_size [%zd] larger than "
415                        "the maximum key size [%d]\n", __func__,
416                        key_rec->enc_key_size,
417                        ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
418                 goto out;
419         }
420         memcpy(key_rec->enc_key, &data[i], key_rec->enc_key_size);
421 out:
422         return rc;
423 }
424
425 /**
426  * ecryptfs_verify_version
427  * @version: The version number to confirm
428  *
429  * Returns zero on good version; non-zero otherwise
430  */
431 static int ecryptfs_verify_version(u16 version)
432 {
433         int rc = 0;
434         unsigned char major;
435         unsigned char minor;
436
437         major = ((version >> 8) & 0xFF);
438         minor = (version & 0xFF);
439         if (major != ECRYPTFS_VERSION_MAJOR) {
440                 ecryptfs_printk(KERN_ERR, "Major version number mismatch. "
441                                 "Expected [%d]; got [%d]\n",
442                                 ECRYPTFS_VERSION_MAJOR, major);
443                 rc = -EINVAL;
444                 goto out;
445         }
446         if (minor != ECRYPTFS_VERSION_MINOR) {
447                 ecryptfs_printk(KERN_ERR, "Minor version number mismatch. "
448                                 "Expected [%d]; got [%d]\n",
449                                 ECRYPTFS_VERSION_MINOR, minor);
450                 rc = -EINVAL;
451                 goto out;
452         }
453 out:
454         return rc;
455 }
456
457 /**
458  * ecryptfs_verify_auth_tok_from_key
459  * @auth_tok_key: key containing the authentication token
460  * @auth_tok: authentication token
461  *
462  * Returns zero on valid auth tok; -EINVAL if the payload is invalid; or
463  * -EKEYREVOKED if the key was revoked before we acquired its semaphore.
464  */
465 static int
466 ecryptfs_verify_auth_tok_from_key(struct key *auth_tok_key,
467                                   struct ecryptfs_auth_tok **auth_tok)
468 {
469         int rc = 0;
470
471         (*auth_tok) = ecryptfs_get_key_payload_data(auth_tok_key);
472         if (IS_ERR(*auth_tok)) {
473                 rc = PTR_ERR(*auth_tok);
474                 *auth_tok = NULL;
475                 goto out;
476         }
477
478         if (ecryptfs_verify_version((*auth_tok)->version)) {
479                 printk(KERN_ERR "Data structure version mismatch. Userspace "
480                        "tools must match eCryptfs kernel module with major "
481                        "version [%d] and minor version [%d]\n",
482                        ECRYPTFS_VERSION_MAJOR, ECRYPTFS_VERSION_MINOR);
483                 rc = -EINVAL;
484                 goto out;
485         }
486         if ((*auth_tok)->token_type != ECRYPTFS_PASSWORD
487             && (*auth_tok)->token_type != ECRYPTFS_PRIVATE_KEY) {
488                 printk(KERN_ERR "Invalid auth_tok structure "
489                        "returned from key query\n");
490                 rc = -EINVAL;
491                 goto out;
492         }
493 out:
494         return rc;
495 }
496
497 static int
498 ecryptfs_find_global_auth_tok_for_sig(
499         struct key **auth_tok_key,
500         struct ecryptfs_auth_tok **auth_tok,
501         struct ecryptfs_mount_crypt_stat *mount_crypt_stat, char *sig)
502 {
503         struct ecryptfs_global_auth_tok *walker;
504         int rc = 0;
505
506         (*auth_tok_key) = NULL;
507         (*auth_tok) = NULL;
508         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
509         list_for_each_entry(walker,
510                             &mount_crypt_stat->global_auth_tok_list,
511                             mount_crypt_stat_list) {
512                 if (memcmp(walker->sig, sig, ECRYPTFS_SIG_SIZE_HEX))
513                         continue;
514
515                 if (walker->flags & ECRYPTFS_AUTH_TOK_INVALID) {
516                         rc = -EINVAL;
517                         goto out;
518                 }
519
520                 rc = key_validate(walker->global_auth_tok_key);
521                 if (rc) {
522                         if (rc == -EKEYEXPIRED)
523                                 goto out;
524                         goto out_invalid_auth_tok;
525                 }
526
527                 down_write(&(walker->global_auth_tok_key->sem));
528                 rc = ecryptfs_verify_auth_tok_from_key(
529                                 walker->global_auth_tok_key, auth_tok);
530                 if (rc)
531                         goto out_invalid_auth_tok_unlock;
532
533                 (*auth_tok_key) = walker->global_auth_tok_key;
534                 key_get(*auth_tok_key);
535                 goto out;
536         }
537         rc = -ENOENT;
538         goto out;
539 out_invalid_auth_tok_unlock:
540         up_write(&(walker->global_auth_tok_key->sem));
541 out_invalid_auth_tok:
542         printk(KERN_WARNING "Invalidating auth tok with sig = [%s]\n", sig);
543         walker->flags |= ECRYPTFS_AUTH_TOK_INVALID;
544         key_put(walker->global_auth_tok_key);
545         walker->global_auth_tok_key = NULL;
546 out:
547         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
548         return rc;
549 }
550
551 /**
552  * ecryptfs_find_auth_tok_for_sig
553  * @auth_tok: Set to the matching auth_tok; NULL if not found
554  * @crypt_stat: inode crypt_stat crypto context
555  * @sig: Sig of auth_tok to find
556  *
557  * For now, this function simply looks at the registered auth_tok's
558  * linked off the mount_crypt_stat, so all the auth_toks that can be
559  * used must be registered at mount time. This function could
560  * potentially try a lot harder to find auth_tok's (e.g., by calling
561  * out to ecryptfsd to dynamically retrieve an auth_tok object) so
562  * that static registration of auth_tok's will no longer be necessary.
563  *
564  * Returns zero on no error; non-zero on error
565  */
566 static int
567 ecryptfs_find_auth_tok_for_sig(
568         struct key **auth_tok_key,
569         struct ecryptfs_auth_tok **auth_tok,
570         struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
571         char *sig)
572 {
573         int rc = 0;
574
575         rc = ecryptfs_find_global_auth_tok_for_sig(auth_tok_key, auth_tok,
576                                                    mount_crypt_stat, sig);
577         if (rc == -ENOENT) {
578                 /* if the flag ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY is set in the
579                  * mount_crypt_stat structure, we prevent to use auth toks that
580                  * are not inserted through the ecryptfs_add_global_auth_tok
581                  * function.
582                  */
583                 if (mount_crypt_stat->flags
584                                 & ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
585                         return -EINVAL;
586
587                 rc = ecryptfs_keyring_auth_tok_for_sig(auth_tok_key, auth_tok,
588                                                        sig);
589         }
590         return rc;
591 }
592
593 /**
594  * write_tag_70_packet can gobble a lot of stack space. We stuff most
595  * of the function's parameters in a kmalloc'd struct to help reduce
596  * eCryptfs' overall stack usage.
597  */
598 struct ecryptfs_write_tag_70_packet_silly_stack {
599         u8 cipher_code;
600         size_t max_packet_size;
601         size_t packet_size_len;
602         size_t block_aligned_filename_size;
603         size_t block_size;
604         size_t i;
605         size_t j;
606         size_t num_rand_bytes;
607         struct mutex *tfm_mutex;
608         char *block_aligned_filename;
609         struct ecryptfs_auth_tok *auth_tok;
610         struct scatterlist src_sg[2];
611         struct scatterlist dst_sg[2];
612         struct crypto_skcipher *skcipher_tfm;
613         struct skcipher_request *skcipher_req;
614         char iv[ECRYPTFS_MAX_IV_BYTES];
615         char hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
616         char tmp_hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
617         struct crypto_shash *hash_tfm;
618         struct shash_desc *hash_desc;
619 };
620
621 /**
622  * write_tag_70_packet - Write encrypted filename (EFN) packet against FNEK
623  * @filename: NULL-terminated filename string
624  *
625  * This is the simplest mechanism for achieving filename encryption in
626  * eCryptfs. It encrypts the given filename with the mount-wide
627  * filename encryption key (FNEK) and stores it in a packet to @dest,
628  * which the callee will encode and write directly into the dentry
629  * name.
630  */
631 int
632 ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
633                              size_t *packet_size,
634                              struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
635                              char *filename, size_t filename_size)
636 {
637         struct ecryptfs_write_tag_70_packet_silly_stack *s;
638         struct key *auth_tok_key = NULL;
639         int rc = 0;
640
641         s = kzalloc(sizeof(*s), GFP_KERNEL);
642         if (!s) {
643                 printk(KERN_ERR "%s: Out of memory whilst trying to kmalloc "
644                        "[%zd] bytes of kernel memory\n", __func__, sizeof(*s));
645                 return -ENOMEM;
646         }
647         (*packet_size) = 0;
648         rc = ecryptfs_find_auth_tok_for_sig(
649                 &auth_tok_key,
650                 &s->auth_tok, mount_crypt_stat,
651                 mount_crypt_stat->global_default_fnek_sig);
652         if (rc) {
653                 printk(KERN_ERR "%s: Error attempting to find auth tok for "
654                        "fnek sig [%s]; rc = [%d]\n", __func__,
655                        mount_crypt_stat->global_default_fnek_sig, rc);
656                 goto out;
657         }
658         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(
659                 &s->skcipher_tfm,
660                 &s->tfm_mutex, mount_crypt_stat->global_default_fn_cipher_name);
661         if (unlikely(rc)) {
662                 printk(KERN_ERR "Internal error whilst attempting to get "
663                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
664                        mount_crypt_stat->global_default_fn_cipher_name, rc);
665                 goto out;
666         }
667         mutex_lock(s->tfm_mutex);
668         s->block_size = crypto_skcipher_blocksize(s->skcipher_tfm);
669         /* Plus one for the \0 separator between the random prefix
670          * and the plaintext filename */
671         s->num_rand_bytes = (ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES + 1);
672         s->block_aligned_filename_size = (s->num_rand_bytes + filename_size);
673         if ((s->block_aligned_filename_size % s->block_size) != 0) {
674                 s->num_rand_bytes += (s->block_size
675                                       - (s->block_aligned_filename_size
676                                          % s->block_size));
677                 s->block_aligned_filename_size = (s->num_rand_bytes
678                                                   + filename_size);
679         }
680         /* Octet 0: Tag 70 identifier
681          * Octets 1-N1: Tag 70 packet size (includes cipher identifier
682          *              and block-aligned encrypted filename size)
683          * Octets N1-N2: FNEK sig (ECRYPTFS_SIG_SIZE)
684          * Octet N2-N3: Cipher identifier (1 octet)
685          * Octets N3-N4: Block-aligned encrypted filename
686          *  - Consists of a minimum number of random characters, a \0
687          *    separator, and then the filename */
688         s->max_packet_size = (ECRYPTFS_TAG_70_MAX_METADATA_SIZE
689                               + s->block_aligned_filename_size);
690         if (dest == NULL) {
691                 (*packet_size) = s->max_packet_size;
692                 goto out_unlock;
693         }
694         if (s->max_packet_size > (*remaining_bytes)) {
695                 printk(KERN_WARNING "%s: Require [%zd] bytes to write; only "
696                        "[%zd] available\n", __func__, s->max_packet_size,
697                        (*remaining_bytes));
698                 rc = -EINVAL;
699                 goto out_unlock;
700         }
701
702         s->skcipher_req = skcipher_request_alloc(s->skcipher_tfm, GFP_KERNEL);
703         if (!s->skcipher_req) {
704                 printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
705                        "skcipher_request_alloc for %s\n", __func__,
706                        crypto_skcipher_driver_name(s->skcipher_tfm));
707                 rc = -ENOMEM;
708                 goto out_unlock;
709         }
710
711         skcipher_request_set_callback(s->skcipher_req,
712                                       CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
713
714         s->block_aligned_filename = kzalloc(s->block_aligned_filename_size,
715                                             GFP_KERNEL);
716         if (!s->block_aligned_filename) {
717                 printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
718                        "kzalloc [%zd] bytes\n", __func__,
719                        s->block_aligned_filename_size);
720                 rc = -ENOMEM;
721                 goto out_unlock;
722         }
723         dest[s->i++] = ECRYPTFS_TAG_70_PACKET_TYPE;
724         rc = ecryptfs_write_packet_length(&dest[s->i],
725                                           (ECRYPTFS_SIG_SIZE
726                                            + 1 /* Cipher code */
727                                            + s->block_aligned_filename_size),
728                                           &s->packet_size_len);
729         if (rc) {
730                 printk(KERN_ERR "%s: Error generating tag 70 packet "
731                        "header; cannot generate packet length; rc = [%d]\n",
732                        __func__, rc);
733                 goto out_free_unlock;
734         }
735         s->i += s->packet_size_len;
736         ecryptfs_from_hex(&dest[s->i],
737                           mount_crypt_stat->global_default_fnek_sig,
738                           ECRYPTFS_SIG_SIZE);
739         s->i += ECRYPTFS_SIG_SIZE;
740         s->cipher_code = ecryptfs_code_for_cipher_string(
741                 mount_crypt_stat->global_default_fn_cipher_name,
742                 mount_crypt_stat->global_default_fn_cipher_key_bytes);
743         if (s->cipher_code == 0) {
744                 printk(KERN_WARNING "%s: Unable to generate code for "
745                        "cipher [%s] with key bytes [%zd]\n", __func__,
746                        mount_crypt_stat->global_default_fn_cipher_name,
747                        mount_crypt_stat->global_default_fn_cipher_key_bytes);
748                 rc = -EINVAL;
749                 goto out_free_unlock;
750         }
751         dest[s->i++] = s->cipher_code;
752         /* TODO: Support other key modules than passphrase for
753          * filename encryption */
754         if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
755                 rc = -EOPNOTSUPP;
756                 printk(KERN_INFO "%s: Filename encryption only supports "
757                        "password tokens\n", __func__);
758                 goto out_free_unlock;
759         }
760         s->hash_tfm = crypto_alloc_shash(ECRYPTFS_TAG_70_DIGEST, 0, 0);
761         if (IS_ERR(s->hash_tfm)) {
762                         rc = PTR_ERR(s->hash_tfm);
763                         printk(KERN_ERR "%s: Error attempting to "
764                                "allocate hash crypto context; rc = [%d]\n",
765                                __func__, rc);
766                         goto out_free_unlock;
767         }
768
769         s->hash_desc = kmalloc(sizeof(*s->hash_desc) +
770                                crypto_shash_descsize(s->hash_tfm), GFP_KERNEL);
771         if (!s->hash_desc) {
772                 printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
773                        "kmalloc [%zd] bytes\n", __func__,
774                        sizeof(*s->hash_desc) +
775                        crypto_shash_descsize(s->hash_tfm));
776                 rc = -ENOMEM;
777                 goto out_release_free_unlock;
778         }
779
780         s->hash_desc->tfm = s->hash_tfm;
781         s->hash_desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
782
783         rc = crypto_shash_digest(s->hash_desc,
784                                  (u8 *)s->auth_tok->token.password.session_key_encryption_key,
785                                  s->auth_tok->token.password.session_key_encryption_key_bytes,
786                                  s->hash);
787         if (rc) {
788                 printk(KERN_ERR
789                        "%s: Error computing crypto hash; rc = [%d]\n",
790                        __func__, rc);
791                 goto out_release_free_unlock;
792         }
793         for (s->j = 0; s->j < (s->num_rand_bytes - 1); s->j++) {
794                 s->block_aligned_filename[s->j] =
795                         s->hash[(s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)];
796                 if ((s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)
797                     == (ECRYPTFS_TAG_70_DIGEST_SIZE - 1)) {
798                         rc = crypto_shash_digest(s->hash_desc, (u8 *)s->hash,
799                                                 ECRYPTFS_TAG_70_DIGEST_SIZE,
800                                                 s->tmp_hash);
801                         if (rc) {
802                                 printk(KERN_ERR
803                                        "%s: Error computing crypto hash; "
804                                        "rc = [%d]\n", __func__, rc);
805                                 goto out_release_free_unlock;
806                         }
807                         memcpy(s->hash, s->tmp_hash,
808                                ECRYPTFS_TAG_70_DIGEST_SIZE);
809                 }
810                 if (s->block_aligned_filename[s->j] == '\0')
811                         s->block_aligned_filename[s->j] = ECRYPTFS_NON_NULL;
812         }
813         memcpy(&s->block_aligned_filename[s->num_rand_bytes], filename,
814                filename_size);
815         rc = virt_to_scatterlist(s->block_aligned_filename,
816                                  s->block_aligned_filename_size, s->src_sg, 2);
817         if (rc < 1) {
818                 printk(KERN_ERR "%s: Internal error whilst attempting to "
819                        "convert filename memory to scatterlist; rc = [%d]. "
820                        "block_aligned_filename_size = [%zd]\n", __func__, rc,
821                        s->block_aligned_filename_size);
822                 goto out_release_free_unlock;
823         }
824         rc = virt_to_scatterlist(&dest[s->i], s->block_aligned_filename_size,
825                                  s->dst_sg, 2);
826         if (rc < 1) {
827                 printk(KERN_ERR "%s: Internal error whilst attempting to "
828                        "convert encrypted filename memory to scatterlist; "
829                        "rc = [%d]. block_aligned_filename_size = [%zd]\n",
830                        __func__, rc, s->block_aligned_filename_size);
831                 goto out_release_free_unlock;
832         }
833         /* The characters in the first block effectively do the job
834          * of the IV here, so we just use 0's for the IV. Note the
835          * constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
836          * >= ECRYPTFS_MAX_IV_BYTES. */
837         rc = crypto_skcipher_setkey(
838                 s->skcipher_tfm,
839                 s->auth_tok->token.password.session_key_encryption_key,
840                 mount_crypt_stat->global_default_fn_cipher_key_bytes);
841         if (rc < 0) {
842                 printk(KERN_ERR "%s: Error setting key for crypto context; "
843                        "rc = [%d]. s->auth_tok->token.password.session_key_"
844                        "encryption_key = [0x%p]; mount_crypt_stat->"
845                        "global_default_fn_cipher_key_bytes = [%zd]\n", __func__,
846                        rc,
847                        s->auth_tok->token.password.session_key_encryption_key,
848                        mount_crypt_stat->global_default_fn_cipher_key_bytes);
849                 goto out_release_free_unlock;
850         }
851         skcipher_request_set_crypt(s->skcipher_req, s->src_sg, s->dst_sg,
852                                    s->block_aligned_filename_size, s->iv);
853         rc = crypto_skcipher_encrypt(s->skcipher_req);
854         if (rc) {
855                 printk(KERN_ERR "%s: Error attempting to encrypt filename; "
856                        "rc = [%d]\n", __func__, rc);
857                 goto out_release_free_unlock;
858         }
859         s->i += s->block_aligned_filename_size;
860         (*packet_size) = s->i;
861         (*remaining_bytes) -= (*packet_size);
862 out_release_free_unlock:
863         crypto_free_shash(s->hash_tfm);
864 out_free_unlock:
865         kzfree(s->block_aligned_filename);
866 out_unlock:
867         mutex_unlock(s->tfm_mutex);
868 out:
869         if (auth_tok_key) {
870                 up_write(&(auth_tok_key->sem));
871                 key_put(auth_tok_key);
872         }
873         skcipher_request_free(s->skcipher_req);
874         kzfree(s->hash_desc);
875         kfree(s);
876         return rc;
877 }
878
879 struct ecryptfs_parse_tag_70_packet_silly_stack {
880         u8 cipher_code;
881         size_t max_packet_size;
882         size_t packet_size_len;
883         size_t parsed_tag_70_packet_size;
884         size_t block_aligned_filename_size;
885         size_t block_size;
886         size_t i;
887         struct mutex *tfm_mutex;
888         char *decrypted_filename;
889         struct ecryptfs_auth_tok *auth_tok;
890         struct scatterlist src_sg[2];
891         struct scatterlist dst_sg[2];
892         struct crypto_skcipher *skcipher_tfm;
893         struct skcipher_request *skcipher_req;
894         char fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX + 1];
895         char iv[ECRYPTFS_MAX_IV_BYTES];
896         char cipher_string[ECRYPTFS_MAX_CIPHER_NAME_SIZE + 1];
897 };
898
899 /**
900  * parse_tag_70_packet - Parse and process FNEK-encrypted passphrase packet
901  * @filename: This function kmalloc's the memory for the filename
902  * @filename_size: This function sets this to the amount of memory
903  *                 kmalloc'd for the filename
904  * @packet_size: This function sets this to the the number of octets
905  *               in the packet parsed
906  * @mount_crypt_stat: The mount-wide cryptographic context
907  * @data: The memory location containing the start of the tag 70
908  *        packet
909  * @max_packet_size: The maximum legal size of the packet to be parsed
910  *                   from @data
911  *
912  * Returns zero on success; non-zero otherwise
913  */
914 int
915 ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
916                              size_t *packet_size,
917                              struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
918                              char *data, size_t max_packet_size)
919 {
920         struct ecryptfs_parse_tag_70_packet_silly_stack *s;
921         struct key *auth_tok_key = NULL;
922         int rc = 0;
923
924         (*packet_size) = 0;
925         (*filename_size) = 0;
926         (*filename) = NULL;
927         s = kzalloc(sizeof(*s), GFP_KERNEL);
928         if (!s) {
929                 printk(KERN_ERR "%s: Out of memory whilst trying to kmalloc "
930                        "[%zd] bytes of kernel memory\n", __func__, sizeof(*s));
931                 return -ENOMEM;
932         }
933         if (max_packet_size < ECRYPTFS_TAG_70_MIN_METADATA_SIZE) {
934                 printk(KERN_WARNING "%s: max_packet_size is [%zd]; it must be "
935                        "at least [%d]\n", __func__, max_packet_size,
936                        ECRYPTFS_TAG_70_MIN_METADATA_SIZE);
937                 rc = -EINVAL;
938                 goto out;
939         }
940         /* Octet 0: Tag 70 identifier
941          * Octets 1-N1: Tag 70 packet size (includes cipher identifier
942          *              and block-aligned encrypted filename size)
943          * Octets N1-N2: FNEK sig (ECRYPTFS_SIG_SIZE)
944          * Octet N2-N3: Cipher identifier (1 octet)
945          * Octets N3-N4: Block-aligned encrypted filename
946          *  - Consists of a minimum number of random numbers, a \0
947          *    separator, and then the filename */
948         if (data[(*packet_size)++] != ECRYPTFS_TAG_70_PACKET_TYPE) {
949                 printk(KERN_WARNING "%s: Invalid packet tag [0x%.2x]; must be "
950                        "tag [0x%.2x]\n", __func__,
951                        data[((*packet_size) - 1)], ECRYPTFS_TAG_70_PACKET_TYPE);
952                 rc = -EINVAL;
953                 goto out;
954         }
955         rc = ecryptfs_parse_packet_length(&data[(*packet_size)],
956                                           &s->parsed_tag_70_packet_size,
957                                           &s->packet_size_len);
958         if (rc) {
959                 printk(KERN_WARNING "%s: Error parsing packet length; "
960                        "rc = [%d]\n", __func__, rc);
961                 goto out;
962         }
963         s->block_aligned_filename_size = (s->parsed_tag_70_packet_size
964                                           - ECRYPTFS_SIG_SIZE - 1);
965         if ((1 + s->packet_size_len + s->parsed_tag_70_packet_size)
966             > max_packet_size) {
967                 printk(KERN_WARNING "%s: max_packet_size is [%zd]; real packet "
968                        "size is [%zd]\n", __func__, max_packet_size,
969                        (1 + s->packet_size_len + 1
970                         + s->block_aligned_filename_size));
971                 rc = -EINVAL;
972                 goto out;
973         }
974         (*packet_size) += s->packet_size_len;
975         ecryptfs_to_hex(s->fnek_sig_hex, &data[(*packet_size)],
976                         ECRYPTFS_SIG_SIZE);
977         s->fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX] = '\0';
978         (*packet_size) += ECRYPTFS_SIG_SIZE;
979         s->cipher_code = data[(*packet_size)++];
980         rc = ecryptfs_cipher_code_to_string(s->cipher_string, s->cipher_code);
981         if (rc) {
982                 printk(KERN_WARNING "%s: Cipher code [%d] is invalid\n",
983                        __func__, s->cipher_code);
984                 goto out;
985         }
986         rc = ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
987                                             &s->auth_tok, mount_crypt_stat,
988                                             s->fnek_sig_hex);
989         if (rc) {
990                 printk(KERN_ERR "%s: Error attempting to find auth tok for "
991                        "fnek sig [%s]; rc = [%d]\n", __func__, s->fnek_sig_hex,
992                        rc);
993                 goto out;
994         }
995         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&s->skcipher_tfm,
996                                                         &s->tfm_mutex,
997                                                         s->cipher_string);
998         if (unlikely(rc)) {
999                 printk(KERN_ERR "Internal error whilst attempting to get "
1000                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
1001                        s->cipher_string, rc);
1002                 goto out;
1003         }
1004         mutex_lock(s->tfm_mutex);
1005         rc = virt_to_scatterlist(&data[(*packet_size)],
1006                                  s->block_aligned_filename_size, s->src_sg, 2);
1007         if (rc < 1) {
1008                 printk(KERN_ERR "%s: Internal error whilst attempting to "
1009                        "convert encrypted filename memory to scatterlist; "
1010                        "rc = [%d]. block_aligned_filename_size = [%zd]\n",
1011                        __func__, rc, s->block_aligned_filename_size);
1012                 goto out_unlock;
1013         }
1014         (*packet_size) += s->block_aligned_filename_size;
1015         s->decrypted_filename = kmalloc(s->block_aligned_filename_size,
1016                                         GFP_KERNEL);
1017         if (!s->decrypted_filename) {
1018                 printk(KERN_ERR "%s: Out of memory whilst attempting to "
1019                        "kmalloc [%zd] bytes\n", __func__,
1020                        s->block_aligned_filename_size);
1021                 rc = -ENOMEM;
1022                 goto out_unlock;
1023         }
1024         rc = virt_to_scatterlist(s->decrypted_filename,
1025                                  s->block_aligned_filename_size, s->dst_sg, 2);
1026         if (rc < 1) {
1027                 printk(KERN_ERR "%s: Internal error whilst attempting to "
1028                        "convert decrypted filename memory to scatterlist; "
1029                        "rc = [%d]. block_aligned_filename_size = [%zd]\n",
1030                        __func__, rc, s->block_aligned_filename_size);
1031                 goto out_free_unlock;
1032         }
1033
1034         s->skcipher_req = skcipher_request_alloc(s->skcipher_tfm, GFP_KERNEL);
1035         if (!s->skcipher_req) {
1036                 printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
1037                        "skcipher_request_alloc for %s\n", __func__,
1038                        crypto_skcipher_driver_name(s->skcipher_tfm));
1039                 rc = -ENOMEM;
1040                 goto out_free_unlock;
1041         }
1042
1043         skcipher_request_set_callback(s->skcipher_req,
1044                                       CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);
1045
1046         /* The characters in the first block effectively do the job of
1047          * the IV here, so we just use 0's for the IV. Note the
1048          * constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
1049          * >= ECRYPTFS_MAX_IV_BYTES. */
1050         /* TODO: Support other key modules than passphrase for
1051          * filename encryption */
1052         if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
1053                 rc = -EOPNOTSUPP;
1054                 printk(KERN_INFO "%s: Filename encryption only supports "
1055                        "password tokens\n", __func__);
1056                 goto out_free_unlock;
1057         }
1058         rc = crypto_skcipher_setkey(
1059                 s->skcipher_tfm,
1060                 s->auth_tok->token.password.session_key_encryption_key,
1061                 mount_crypt_stat->global_default_fn_cipher_key_bytes);
1062         if (rc < 0) {
1063                 printk(KERN_ERR "%s: Error setting key for crypto context; "
1064                        "rc = [%d]. s->auth_tok->token.password.session_key_"
1065                        "encryption_key = [0x%p]; mount_crypt_stat->"
1066                        "global_default_fn_cipher_key_bytes = [%zd]\n", __func__,
1067                        rc,
1068                        s->auth_tok->token.password.session_key_encryption_key,
1069                        mount_crypt_stat->global_default_fn_cipher_key_bytes);
1070                 goto out_free_unlock;
1071         }
1072         skcipher_request_set_crypt(s->skcipher_req, s->src_sg, s->dst_sg,
1073                                    s->block_aligned_filename_size, s->iv);
1074         rc = crypto_skcipher_decrypt(s->skcipher_req);
1075         if (rc) {
1076                 printk(KERN_ERR "%s: Error attempting to decrypt filename; "
1077                        "rc = [%d]\n", __func__, rc);
1078                 goto out_free_unlock;
1079         }
1080         while (s->decrypted_filename[s->i] != '\0'
1081                && s->i < s->block_aligned_filename_size)
1082                 s->i++;
1083         if (s->i == s->block_aligned_filename_size) {
1084                 printk(KERN_WARNING "%s: Invalid tag 70 packet; could not "
1085                        "find valid separator between random characters and "
1086                        "the filename\n", __func__);
1087                 rc = -EINVAL;
1088                 goto out_free_unlock;
1089         }
1090         s->i++;
1091         (*filename_size) = (s->block_aligned_filename_size - s->i);
1092         if (!((*filename_size) > 0 && (*filename_size < PATH_MAX))) {
1093                 printk(KERN_WARNING "%s: Filename size is [%zd], which is "
1094                        "invalid\n", __func__, (*filename_size));
1095                 rc = -EINVAL;
1096                 goto out_free_unlock;
1097         }
1098         (*filename) = kmalloc(((*filename_size) + 1), GFP_KERNEL);
1099         if (!(*filename)) {
1100                 printk(KERN_ERR "%s: Out of memory whilst attempting to "
1101                        "kmalloc [%zd] bytes\n", __func__,
1102                        ((*filename_size) + 1));
1103                 rc = -ENOMEM;
1104                 goto out_free_unlock;
1105         }
1106         memcpy((*filename), &s->decrypted_filename[s->i], (*filename_size));
1107         (*filename)[(*filename_size)] = '\0';
1108 out_free_unlock:
1109         kfree(s->decrypted_filename);
1110 out_unlock:
1111         mutex_unlock(s->tfm_mutex);
1112 out:
1113         if (rc) {
1114                 (*packet_size) = 0;
1115                 (*filename_size) = 0;
1116                 (*filename) = NULL;
1117         }
1118         if (auth_tok_key) {
1119                 up_write(&(auth_tok_key->sem));
1120                 key_put(auth_tok_key);
1121         }
1122         skcipher_request_free(s->skcipher_req);
1123         kfree(s);
1124         return rc;
1125 }
1126
1127 static int
1128 ecryptfs_get_auth_tok_sig(char **sig, struct ecryptfs_auth_tok *auth_tok)
1129 {
1130         int rc = 0;
1131
1132         (*sig) = NULL;
1133         switch (auth_tok->token_type) {
1134         case ECRYPTFS_PASSWORD:
1135                 (*sig) = auth_tok->token.password.signature;
1136                 break;
1137         case ECRYPTFS_PRIVATE_KEY:
1138                 (*sig) = auth_tok->token.private_key.signature;
1139                 break;
1140         default:
1141                 printk(KERN_ERR "Cannot get sig for auth_tok of type [%d]\n",
1142                        auth_tok->token_type);
1143                 rc = -EINVAL;
1144         }
1145         return rc;
1146 }
1147
1148 /**
1149  * decrypt_pki_encrypted_session_key - Decrypt the session key with the given auth_tok.
1150  * @auth_tok: The key authentication token used to decrypt the session key
1151  * @crypt_stat: The cryptographic context
1152  *
1153  * Returns zero on success; non-zero error otherwise.
1154  */
1155 static int
1156 decrypt_pki_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
1157                                   struct ecryptfs_crypt_stat *crypt_stat)
1158 {
1159         u8 cipher_code = 0;
1160         struct ecryptfs_msg_ctx *msg_ctx;
1161         struct ecryptfs_message *msg = NULL;
1162         char *auth_tok_sig;
1163         char *payload = NULL;
1164         size_t payload_len = 0;
1165         int rc;
1166
1167         rc = ecryptfs_get_auth_tok_sig(&auth_tok_sig, auth_tok);
1168         if (rc) {
1169                 printk(KERN_ERR "Unrecognized auth tok type: [%d]\n",
1170                        auth_tok->token_type);
1171                 goto out;
1172         }
1173         rc = write_tag_64_packet(auth_tok_sig, &(auth_tok->session_key),
1174                                  &payload, &payload_len);
1175         if (rc) {
1176                 ecryptfs_printk(KERN_ERR, "Failed to write tag 64 packet\n");
1177                 goto out;
1178         }
1179         rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);
1180         if (rc) {
1181                 ecryptfs_printk(KERN_ERR, "Error sending message to "
1182                                 "ecryptfsd: %d\n", rc);
1183                 goto out;
1184         }
1185         rc = ecryptfs_wait_for_response(msg_ctx, &msg);
1186         if (rc) {
1187                 ecryptfs_printk(KERN_ERR, "Failed to receive tag 65 packet "
1188                                 "from the user space daemon\n");
1189                 rc = -EIO;
1190                 goto out;
1191         }
1192         rc = parse_tag_65_packet(&(auth_tok->session_key),
1193                                  &cipher_code, msg);
1194         if (rc) {
1195                 printk(KERN_ERR "Failed to parse tag 65 packet; rc = [%d]\n",
1196                        rc);
1197                 goto out;
1198         }
1199         auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1200         memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
1201                auth_tok->session_key.decrypted_key_size);
1202         crypt_stat->key_size = auth_tok->session_key.decrypted_key_size;
1203         rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher, cipher_code);
1204         if (rc) {
1205                 ecryptfs_printk(KERN_ERR, "Cipher code [%d] is invalid\n",
1206                                 cipher_code)
1207                 goto out;
1208         }
1209         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
1210         if (ecryptfs_verbosity > 0) {
1211                 ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n");
1212                 ecryptfs_dump_hex(crypt_stat->key,
1213                                   crypt_stat->key_size);
1214         }
1215 out:
1216         kfree(msg);
1217         kfree(payload);
1218         return rc;
1219 }
1220
1221 static void wipe_auth_tok_list(struct list_head *auth_tok_list_head)
1222 {
1223         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1224         struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;
1225
1226         list_for_each_entry_safe(auth_tok_list_item, auth_tok_list_item_tmp,
1227                                  auth_tok_list_head, list) {
1228                 list_del(&auth_tok_list_item->list);
1229                 kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1230                                 auth_tok_list_item);
1231         }
1232 }
1233
1234 struct kmem_cache *ecryptfs_auth_tok_list_item_cache;
1235
1236 /**
1237  * parse_tag_1_packet
1238  * @crypt_stat: The cryptographic context to modify based on packet contents
1239  * @data: The raw bytes of the packet.
1240  * @auth_tok_list: eCryptfs parses packets into authentication tokens;
1241  *                 a new authentication token will be placed at the
1242  *                 end of this list for this packet.
1243  * @new_auth_tok: Pointer to a pointer to memory that this function
1244  *                allocates; sets the memory address of the pointer to
1245  *                NULL on error. This object is added to the
1246  *                auth_tok_list.
1247  * @packet_size: This function writes the size of the parsed packet
1248  *               into this memory location; zero on error.
1249  * @max_packet_size: The maximum allowable packet size
1250  *
1251  * Returns zero on success; non-zero on error.
1252  */
1253 static int
1254 parse_tag_1_packet(struct ecryptfs_crypt_stat *crypt_stat,
1255                    unsigned char *data, struct list_head *auth_tok_list,
1256                    struct ecryptfs_auth_tok **new_auth_tok,
1257                    size_t *packet_size, size_t max_packet_size)
1258 {
1259         size_t body_size;
1260         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1261         size_t length_size;
1262         int rc = 0;
1263
1264         (*packet_size) = 0;
1265         (*new_auth_tok) = NULL;
1266         /**
1267          * This format is inspired by OpenPGP; see RFC 2440
1268          * packet tag 1
1269          *
1270          * Tag 1 identifier (1 byte)
1271          * Max Tag 1 packet size (max 3 bytes)
1272          * Version (1 byte)
1273          * Key identifier (8 bytes; ECRYPTFS_SIG_SIZE)
1274          * Cipher identifier (1 byte)
1275          * Encrypted key size (arbitrary)
1276          *
1277          * 12 bytes minimum packet size
1278          */
1279         if (unlikely(max_packet_size < 12)) {
1280                 printk(KERN_ERR "Invalid max packet size; must be >=12\n");
1281                 rc = -EINVAL;
1282                 goto out;
1283         }
1284         if (data[(*packet_size)++] != ECRYPTFS_TAG_1_PACKET_TYPE) {
1285                 printk(KERN_ERR "Enter w/ first byte != 0x%.2x\n",
1286                        ECRYPTFS_TAG_1_PACKET_TYPE);
1287                 rc = -EINVAL;
1288                 goto out;
1289         }
1290         /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
1291          * at end of function upon failure */
1292         auth_tok_list_item =
1293                 kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache,
1294                                   GFP_KERNEL);
1295         if (!auth_tok_list_item) {
1296                 printk(KERN_ERR "Unable to allocate memory\n");
1297                 rc = -ENOMEM;
1298                 goto out;
1299         }
1300         (*new_auth_tok) = &auth_tok_list_item->auth_tok;
1301         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1302                                           &length_size);
1303         if (rc) {
1304                 printk(KERN_WARNING "Error parsing packet length; "
1305                        "rc = [%d]\n", rc);
1306                 goto out_free;
1307         }
1308         if (unlikely(body_size < (ECRYPTFS_SIG_SIZE + 2))) {
1309                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1310                 rc = -EINVAL;
1311                 goto out_free;
1312         }
1313         (*packet_size) += length_size;
1314         if (unlikely((*packet_size) + body_size > max_packet_size)) {
1315                 printk(KERN_WARNING "Packet size exceeds max\n");
1316                 rc = -EINVAL;
1317                 goto out_free;
1318         }
1319         if (unlikely(data[(*packet_size)++] != 0x03)) {
1320                 printk(KERN_WARNING "Unknown version number [%d]\n",
1321                        data[(*packet_size) - 1]);
1322                 rc = -EINVAL;
1323                 goto out_free;
1324         }
1325         ecryptfs_to_hex((*new_auth_tok)->token.private_key.signature,
1326                         &data[(*packet_size)], ECRYPTFS_SIG_SIZE);
1327         *packet_size += ECRYPTFS_SIG_SIZE;
1328         /* This byte is skipped because the kernel does not need to
1329          * know which public key encryption algorithm was used */
1330         (*packet_size)++;
1331         (*new_auth_tok)->session_key.encrypted_key_size =
1332                 body_size - (ECRYPTFS_SIG_SIZE + 2);
1333         if ((*new_auth_tok)->session_key.encrypted_key_size
1334             > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
1335                 printk(KERN_WARNING "Tag 1 packet contains key larger "
1336                        "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES");
1337                 rc = -EINVAL;
1338                 goto out;
1339         }
1340         memcpy((*new_auth_tok)->session_key.encrypted_key,
1341                &data[(*packet_size)], (body_size - (ECRYPTFS_SIG_SIZE + 2)));
1342         (*packet_size) += (*new_auth_tok)->session_key.encrypted_key_size;
1343         (*new_auth_tok)->session_key.flags &=
1344                 ~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1345         (*new_auth_tok)->session_key.flags |=
1346                 ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
1347         (*new_auth_tok)->token_type = ECRYPTFS_PRIVATE_KEY;
1348         (*new_auth_tok)->flags = 0;
1349         (*new_auth_tok)->session_key.flags &=
1350                 ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
1351         (*new_auth_tok)->session_key.flags &=
1352                 ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
1353         list_add(&auth_tok_list_item->list, auth_tok_list);
1354         goto out;
1355 out_free:
1356         (*new_auth_tok) = NULL;
1357         memset(auth_tok_list_item, 0,
1358                sizeof(struct ecryptfs_auth_tok_list_item));
1359         kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1360                         auth_tok_list_item);
1361 out:
1362         if (rc)
1363                 (*packet_size) = 0;
1364         return rc;
1365 }
1366
1367 /**
1368  * parse_tag_3_packet
1369  * @crypt_stat: The cryptographic context to modify based on packet
1370  *              contents.
1371  * @data: The raw bytes of the packet.
1372  * @auth_tok_list: eCryptfs parses packets into authentication tokens;
1373  *                 a new authentication token will be placed at the end
1374  *                 of this list for this packet.
1375  * @new_auth_tok: Pointer to a pointer to memory that this function
1376  *                allocates; sets the memory address of the pointer to
1377  *                NULL on error. This object is added to the
1378  *                auth_tok_list.
1379  * @packet_size: This function writes the size of the parsed packet
1380  *               into this memory location; zero on error.
1381  * @max_packet_size: maximum number of bytes to parse
1382  *
1383  * Returns zero on success; non-zero on error.
1384  */
1385 static int
1386 parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat,
1387                    unsigned char *data, struct list_head *auth_tok_list,
1388                    struct ecryptfs_auth_tok **new_auth_tok,
1389                    size_t *packet_size, size_t max_packet_size)
1390 {
1391         size_t body_size;
1392         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1393         size_t length_size;
1394         int rc = 0;
1395
1396         (*packet_size) = 0;
1397         (*new_auth_tok) = NULL;
1398         /**
1399          *This format is inspired by OpenPGP; see RFC 2440
1400          * packet tag 3
1401          *
1402          * Tag 3 identifier (1 byte)
1403          * Max Tag 3 packet size (max 3 bytes)
1404          * Version (1 byte)
1405          * Cipher code (1 byte)
1406          * S2K specifier (1 byte)
1407          * Hash identifier (1 byte)
1408          * Salt (ECRYPTFS_SALT_SIZE)
1409          * Hash iterations (1 byte)
1410          * Encrypted key (arbitrary)
1411          *
1412          * (ECRYPTFS_SALT_SIZE + 7) minimum packet size
1413          */
1414         if (max_packet_size < (ECRYPTFS_SALT_SIZE + 7)) {
1415                 printk(KERN_ERR "Max packet size too large\n");
1416                 rc = -EINVAL;
1417                 goto out;
1418         }
1419         if (data[(*packet_size)++] != ECRYPTFS_TAG_3_PACKET_TYPE) {
1420                 printk(KERN_ERR "First byte != 0x%.2x; invalid packet\n",
1421                        ECRYPTFS_TAG_3_PACKET_TYPE);
1422                 rc = -EINVAL;
1423                 goto out;
1424         }
1425         /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
1426          * at end of function upon failure */
1427         auth_tok_list_item =
1428             kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache, GFP_KERNEL);
1429         if (!auth_tok_list_item) {
1430                 printk(KERN_ERR "Unable to allocate memory\n");
1431                 rc = -ENOMEM;
1432                 goto out;
1433         }
1434         (*new_auth_tok) = &auth_tok_list_item->auth_tok;
1435         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1436                                           &length_size);
1437         if (rc) {
1438                 printk(KERN_WARNING "Error parsing packet length; rc = [%d]\n",
1439                        rc);
1440                 goto out_free;
1441         }
1442         if (unlikely(body_size < (ECRYPTFS_SALT_SIZE + 5))) {
1443                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1444                 rc = -EINVAL;
1445                 goto out_free;
1446         }
1447         (*packet_size) += length_size;
1448         if (unlikely((*packet_size) + body_size > max_packet_size)) {
1449                 printk(KERN_ERR "Packet size exceeds max\n");
1450                 rc = -EINVAL;
1451                 goto out_free;
1452         }
1453         (*new_auth_tok)->session_key.encrypted_key_size =
1454                 (body_size - (ECRYPTFS_SALT_SIZE + 5));
1455         if ((*new_auth_tok)->session_key.encrypted_key_size
1456             > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
1457                 printk(KERN_WARNING "Tag 3 packet contains key larger "
1458                        "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES\n");
1459                 rc = -EINVAL;
1460                 goto out_free;
1461         }
1462         if (unlikely(data[(*packet_size)++] != 0x04)) {
1463                 printk(KERN_WARNING "Unknown version number [%d]\n",
1464                        data[(*packet_size) - 1]);
1465                 rc = -EINVAL;
1466                 goto out_free;
1467         }
1468         rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher,
1469                                             (u16)data[(*packet_size)]);
1470         if (rc)
1471                 goto out_free;
1472         /* A little extra work to differentiate among the AES key
1473          * sizes; see RFC2440 */
1474         switch(data[(*packet_size)++]) {
1475         case RFC2440_CIPHER_AES_192:
1476                 crypt_stat->key_size = 24;
1477                 break;
1478         default:
1479                 crypt_stat->key_size =
1480                         (*new_auth_tok)->session_key.encrypted_key_size;
1481         }
1482         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1483         if (rc)
1484                 goto out_free;
1485         if (unlikely(data[(*packet_size)++] != 0x03)) {
1486                 printk(KERN_WARNING "Only S2K ID 3 is currently supported\n");
1487                 rc = -ENOSYS;
1488                 goto out_free;
1489         }
1490         /* TODO: finish the hash mapping */
1491         switch (data[(*packet_size)++]) {
1492         case 0x01: /* See RFC2440 for these numbers and their mappings */
1493                 /* Choose MD5 */
1494                 memcpy((*new_auth_tok)->token.password.salt,
1495                        &data[(*packet_size)], ECRYPTFS_SALT_SIZE);
1496                 (*packet_size) += ECRYPTFS_SALT_SIZE;
1497                 /* This conversion was taken straight from RFC2440 */
1498                 (*new_auth_tok)->token.password.hash_iterations =
1499                         ((u32) 16 + (data[(*packet_size)] & 15))
1500                                 << ((data[(*packet_size)] >> 4) + 6);
1501                 (*packet_size)++;
1502                 /* Friendly reminder:
1503                  * (*new_auth_tok)->session_key.encrypted_key_size =
1504                  *         (body_size - (ECRYPTFS_SALT_SIZE + 5)); */
1505                 memcpy((*new_auth_tok)->session_key.encrypted_key,
1506                        &data[(*packet_size)],
1507                        (*new_auth_tok)->session_key.encrypted_key_size);
1508                 (*packet_size) +=
1509                         (*new_auth_tok)->session_key.encrypted_key_size;
1510                 (*new_auth_tok)->session_key.flags &=
1511                         ~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1512                 (*new_auth_tok)->session_key.flags |=
1513                         ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
1514                 (*new_auth_tok)->token.password.hash_algo = 0x01; /* MD5 */
1515                 break;
1516         default:
1517                 ecryptfs_printk(KERN_ERR, "Unsupported hash algorithm: "
1518                                 "[%d]\n", data[(*packet_size) - 1]);
1519                 rc = -ENOSYS;
1520                 goto out_free;
1521         }
1522         (*new_auth_tok)->token_type = ECRYPTFS_PASSWORD;
1523         /* TODO: Parametarize; we might actually want userspace to
1524          * decrypt the session key. */
1525         (*new_auth_tok)->session_key.flags &=
1526                             ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
1527         (*new_auth_tok)->session_key.flags &=
1528                             ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
1529         list_add(&auth_tok_list_item->list, auth_tok_list);
1530         goto out;
1531 out_free:
1532         (*new_auth_tok) = NULL;
1533         memset(auth_tok_list_item, 0,
1534                sizeof(struct ecryptfs_auth_tok_list_item));
1535         kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
1536                         auth_tok_list_item);
1537 out:
1538         if (rc)
1539                 (*packet_size) = 0;
1540         return rc;
1541 }
1542
1543 /**
1544  * parse_tag_11_packet
1545  * @data: The raw bytes of the packet
1546  * @contents: This function writes the data contents of the literal
1547  *            packet into this memory location
1548  * @max_contents_bytes: The maximum number of bytes that this function
1549  *                      is allowed to write into contents
1550  * @tag_11_contents_size: This function writes the size of the parsed
1551  *                        contents into this memory location; zero on
1552  *                        error
1553  * @packet_size: This function writes the size of the parsed packet
1554  *               into this memory location; zero on error
1555  * @max_packet_size: maximum number of bytes to parse
1556  *
1557  * Returns zero on success; non-zero on error.
1558  */
1559 static int
1560 parse_tag_11_packet(unsigned char *data, unsigned char *contents,
1561                     size_t max_contents_bytes, size_t *tag_11_contents_size,
1562                     size_t *packet_size, size_t max_packet_size)
1563 {
1564         size_t body_size;
1565         size_t length_size;
1566         int rc = 0;
1567
1568         (*packet_size) = 0;
1569         (*tag_11_contents_size) = 0;
1570         /* This format is inspired by OpenPGP; see RFC 2440
1571          * packet tag 11
1572          *
1573          * Tag 11 identifier (1 byte)
1574          * Max Tag 11 packet size (max 3 bytes)
1575          * Binary format specifier (1 byte)
1576          * Filename length (1 byte)
1577          * Filename ("_CONSOLE") (8 bytes)
1578          * Modification date (4 bytes)
1579          * Literal data (arbitrary)
1580          *
1581          * We need at least 16 bytes of data for the packet to even be
1582          * valid.
1583          */
1584         if (max_packet_size < 16) {
1585                 printk(KERN_ERR "Maximum packet size too small\n");
1586                 rc = -EINVAL;
1587                 goto out;
1588         }
1589         if (data[(*packet_size)++] != ECRYPTFS_TAG_11_PACKET_TYPE) {
1590                 printk(KERN_WARNING "Invalid tag 11 packet format\n");
1591                 rc = -EINVAL;
1592                 goto out;
1593         }
1594         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
1595                                           &length_size);
1596         if (rc) {
1597                 printk(KERN_WARNING "Invalid tag 11 packet format\n");
1598                 goto out;
1599         }
1600         if (body_size < 14) {
1601                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1602                 rc = -EINVAL;
1603                 goto out;
1604         }
1605         (*packet_size) += length_size;
1606         (*tag_11_contents_size) = (body_size - 14);
1607         if (unlikely((*packet_size) + body_size + 1 > max_packet_size)) {
1608                 printk(KERN_ERR "Packet size exceeds max\n");
1609                 rc = -EINVAL;
1610                 goto out;
1611         }
1612         if (unlikely((*tag_11_contents_size) > max_contents_bytes)) {
1613                 printk(KERN_ERR "Literal data section in tag 11 packet exceeds "
1614                        "expected size\n");
1615                 rc = -EINVAL;
1616                 goto out;
1617         }
1618         if (data[(*packet_size)++] != 0x62) {
1619                 printk(KERN_WARNING "Unrecognizable packet\n");
1620                 rc = -EINVAL;
1621                 goto out;
1622         }
1623         if (data[(*packet_size)++] != 0x08) {
1624                 printk(KERN_WARNING "Unrecognizable packet\n");
1625                 rc = -EINVAL;
1626                 goto out;
1627         }
1628         (*packet_size) += 12; /* Ignore filename and modification date */
1629         memcpy(contents, &data[(*packet_size)], (*tag_11_contents_size));
1630         (*packet_size) += (*tag_11_contents_size);
1631 out:
1632         if (rc) {
1633                 (*packet_size) = 0;
1634                 (*tag_11_contents_size) = 0;
1635         }
1636         return rc;
1637 }
1638
1639 int ecryptfs_keyring_auth_tok_for_sig(struct key **auth_tok_key,
1640                                       struct ecryptfs_auth_tok **auth_tok,
1641                                       char *sig)
1642 {
1643         int rc = 0;
1644
1645         (*auth_tok_key) = request_key(&key_type_user, sig, NULL);
1646         if (!(*auth_tok_key) || IS_ERR(*auth_tok_key)) {
1647                 (*auth_tok_key) = ecryptfs_get_encrypted_key(sig);
1648                 if (!(*auth_tok_key) || IS_ERR(*auth_tok_key)) {
1649                         printk(KERN_ERR "Could not find key with description: [%s]\n",
1650                               sig);
1651                         rc = process_request_key_err(PTR_ERR(*auth_tok_key));
1652                         (*auth_tok_key) = NULL;
1653                         goto out;
1654                 }
1655         }
1656         down_write(&(*auth_tok_key)->sem);
1657         rc = ecryptfs_verify_auth_tok_from_key(*auth_tok_key, auth_tok);
1658         if (rc) {
1659                 up_write(&(*auth_tok_key)->sem);
1660                 key_put(*auth_tok_key);
1661                 (*auth_tok_key) = NULL;
1662                 goto out;
1663         }
1664 out:
1665         return rc;
1666 }
1667
1668 /**
1669  * decrypt_passphrase_encrypted_session_key - Decrypt the session key with the given auth_tok.
1670  * @auth_tok: The passphrase authentication token to use to encrypt the FEK
1671  * @crypt_stat: The cryptographic context
1672  *
1673  * Returns zero on success; non-zero error otherwise
1674  */
1675 static int
1676 decrypt_passphrase_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
1677                                          struct ecryptfs_crypt_stat *crypt_stat)
1678 {
1679         struct scatterlist dst_sg[2];
1680         struct scatterlist src_sg[2];
1681         struct mutex *tfm_mutex;
1682         struct crypto_skcipher *tfm;
1683         struct skcipher_request *req = NULL;
1684         int rc = 0;
1685
1686         if (unlikely(ecryptfs_verbosity > 0)) {
1687                 ecryptfs_printk(
1688                         KERN_DEBUG, "Session key encryption key (size [%d]):\n",
1689                         auth_tok->token.password.session_key_encryption_key_bytes);
1690                 ecryptfs_dump_hex(
1691                         auth_tok->token.password.session_key_encryption_key,
1692                         auth_tok->token.password.session_key_encryption_key_bytes);
1693         }
1694         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex,
1695                                                         crypt_stat->cipher);
1696         if (unlikely(rc)) {
1697                 printk(KERN_ERR "Internal error whilst attempting to get "
1698                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
1699                        crypt_stat->cipher, rc);
1700                 goto out;
1701         }
1702         rc = virt_to_scatterlist(auth_tok->session_key.encrypted_key,
1703                                  auth_tok->session_key.encrypted_key_size,
1704                                  src_sg, 2);
1705         if (rc < 1 || rc > 2) {
1706                 printk(KERN_ERR "Internal error whilst attempting to convert "
1707                         "auth_tok->session_key.encrypted_key to scatterlist; "
1708                         "expected rc = 1; got rc = [%d]. "
1709                        "auth_tok->session_key.encrypted_key_size = [%d]\n", rc,
1710                         auth_tok->session_key.encrypted_key_size);
1711                 goto out;
1712         }
1713         auth_tok->session_key.decrypted_key_size =
1714                 auth_tok->session_key.encrypted_key_size;
1715         rc = virt_to_scatterlist(auth_tok->session_key.decrypted_key,
1716                                  auth_tok->session_key.decrypted_key_size,
1717                                  dst_sg, 2);
1718         if (rc < 1 || rc > 2) {
1719                 printk(KERN_ERR "Internal error whilst attempting to convert "
1720                         "auth_tok->session_key.decrypted_key to scatterlist; "
1721                         "expected rc = 1; got rc = [%d]\n", rc);
1722                 goto out;
1723         }
1724         mutex_lock(tfm_mutex);
1725         req = skcipher_request_alloc(tfm, GFP_KERNEL);
1726         if (!req) {
1727                 mutex_unlock(tfm_mutex);
1728                 printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
1729                        "skcipher_request_alloc for %s\n", __func__,
1730                        crypto_skcipher_driver_name(tfm));
1731                 rc = -ENOMEM;
1732                 goto out;
1733         }
1734
1735         skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP,
1736                                       NULL, NULL);
1737         rc = crypto_skcipher_setkey(
1738                 tfm, auth_tok->token.password.session_key_encryption_key,
1739                 crypt_stat->key_size);
1740         if (unlikely(rc < 0)) {
1741                 mutex_unlock(tfm_mutex);
1742                 printk(KERN_ERR "Error setting key for crypto context\n");
1743                 rc = -EINVAL;
1744                 goto out;
1745         }
1746         skcipher_request_set_crypt(req, src_sg, dst_sg,
1747                                    auth_tok->session_key.encrypted_key_size,
1748                                    NULL);
1749         rc = crypto_skcipher_decrypt(req);
1750         mutex_unlock(tfm_mutex);
1751         if (unlikely(rc)) {
1752                 printk(KERN_ERR "Error decrypting; rc = [%d]\n", rc);
1753                 goto out;
1754         }
1755         auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
1756         memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
1757                auth_tok->session_key.decrypted_key_size);
1758         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
1759         if (unlikely(ecryptfs_verbosity > 0)) {
1760                 ecryptfs_printk(KERN_DEBUG, "FEK of size [%zd]:\n",
1761                                 crypt_stat->key_size);
1762                 ecryptfs_dump_hex(crypt_stat->key,
1763                                   crypt_stat->key_size);
1764         }
1765 out:
1766         skcipher_request_free(req);
1767         return rc;
1768 }
1769
1770 /**
1771  * ecryptfs_parse_packet_set
1772  * @crypt_stat: The cryptographic context
1773  * @src: Virtual address of region of memory containing the packets
1774  * @ecryptfs_dentry: The eCryptfs dentry associated with the packet set
1775  *
1776  * Get crypt_stat to have the file's session key if the requisite key
1777  * is available to decrypt the session key.
1778  *
1779  * Returns Zero if a valid authentication token was retrieved and
1780  * processed; negative value for file not encrypted or for error
1781  * conditions.
1782  */
1783 int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
1784                               unsigned char *src,
1785                               struct dentry *ecryptfs_dentry)
1786 {
1787         size_t i = 0;
1788         size_t found_auth_tok;
1789         size_t next_packet_is_auth_tok_packet;
1790         struct list_head auth_tok_list;
1791         struct ecryptfs_auth_tok *matching_auth_tok;
1792         struct ecryptfs_auth_tok *candidate_auth_tok;
1793         char *candidate_auth_tok_sig;
1794         size_t packet_size;
1795         struct ecryptfs_auth_tok *new_auth_tok;
1796         unsigned char sig_tmp_space[ECRYPTFS_SIG_SIZE];
1797         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1798         size_t tag_11_contents_size;
1799         size_t tag_11_packet_size;
1800         struct key *auth_tok_key = NULL;
1801         int rc = 0;
1802
1803         INIT_LIST_HEAD(&auth_tok_list);
1804         /* Parse the header to find as many packets as we can; these will be
1805          * added the our &auth_tok_list */
1806         next_packet_is_auth_tok_packet = 1;
1807         while (next_packet_is_auth_tok_packet) {
1808                 size_t max_packet_size = ((PAGE_SIZE - 8) - i);
1809
1810                 switch (src[i]) {
1811                 case ECRYPTFS_TAG_3_PACKET_TYPE:
1812                         rc = parse_tag_3_packet(crypt_stat,
1813                                                 (unsigned char *)&src[i],
1814                                                 &auth_tok_list, &new_auth_tok,
1815                                                 &packet_size, max_packet_size);
1816                         if (rc) {
1817                                 ecryptfs_printk(KERN_ERR, "Error parsing "
1818                                                 "tag 3 packet\n");
1819                                 rc = -EIO;
1820                                 goto out_wipe_list;
1821                         }
1822                         i += packet_size;
1823                         rc = parse_tag_11_packet((unsigned char *)&src[i],
1824                                                  sig_tmp_space,
1825                                                  ECRYPTFS_SIG_SIZE,
1826                                                  &tag_11_contents_size,
1827                                                  &tag_11_packet_size,
1828                                                  max_packet_size);
1829                         if (rc) {
1830                                 ecryptfs_printk(KERN_ERR, "No valid "
1831                                                 "(ecryptfs-specific) literal "
1832                                                 "packet containing "
1833                                                 "authentication token "
1834                                                 "signature found after "
1835                                                 "tag 3 packet\n");
1836                                 rc = -EIO;
1837                                 goto out_wipe_list;
1838                         }
1839                         i += tag_11_packet_size;
1840                         if (ECRYPTFS_SIG_SIZE != tag_11_contents_size) {
1841                                 ecryptfs_printk(KERN_ERR, "Expected "
1842                                                 "signature of size [%d]; "
1843                                                 "read size [%zd]\n",
1844                                                 ECRYPTFS_SIG_SIZE,
1845                                                 tag_11_contents_size);
1846                                 rc = -EIO;
1847                                 goto out_wipe_list;
1848                         }
1849                         ecryptfs_to_hex(new_auth_tok->token.password.signature,
1850                                         sig_tmp_space, tag_11_contents_size);
1851                         new_auth_tok->token.password.signature[
1852                                 ECRYPTFS_PASSWORD_SIG_SIZE] = '\0';
1853                         crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
1854                         break;
1855                 case ECRYPTFS_TAG_1_PACKET_TYPE:
1856                         rc = parse_tag_1_packet(crypt_stat,
1857                                                 (unsigned char *)&src[i],
1858                                                 &auth_tok_list, &new_auth_tok,
1859                                                 &packet_size, max_packet_size);
1860                         if (rc) {
1861                                 ecryptfs_printk(KERN_ERR, "Error parsing "
1862                                                 "tag 1 packet\n");
1863                                 rc = -EIO;
1864                                 goto out_wipe_list;
1865                         }
1866                         i += packet_size;
1867                         crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
1868                         break;
1869                 case ECRYPTFS_TAG_11_PACKET_TYPE:
1870                         ecryptfs_printk(KERN_WARNING, "Invalid packet set "
1871                                         "(Tag 11 not allowed by itself)\n");
1872                         rc = -EIO;
1873                         goto out_wipe_list;
1874                 default:
1875                         ecryptfs_printk(KERN_DEBUG, "No packet at offset [%zd] "
1876                                         "of the file header; hex value of "
1877                                         "character is [0x%.2x]\n", i, src[i]);
1878                         next_packet_is_auth_tok_packet = 0;
1879                 }
1880         }
1881         if (list_empty(&auth_tok_list)) {
1882                 printk(KERN_ERR "The lower file appears to be a non-encrypted "
1883                        "eCryptfs file; this is not supported in this version "
1884                        "of the eCryptfs kernel module\n");
1885                 rc = -EINVAL;
1886                 goto out;
1887         }
1888         /* auth_tok_list contains the set of authentication tokens
1889          * parsed from the metadata. We need to find a matching
1890          * authentication token that has the secret component(s)
1891          * necessary to decrypt the EFEK in the auth_tok parsed from
1892          * the metadata. There may be several potential matches, but
1893          * just one will be sufficient to decrypt to get the FEK. */
1894 find_next_matching_auth_tok:
1895         found_auth_tok = 0;
1896         list_for_each_entry(auth_tok_list_item, &auth_tok_list, list) {
1897                 candidate_auth_tok = &auth_tok_list_item->auth_tok;
1898                 if (unlikely(ecryptfs_verbosity > 0)) {
1899                         ecryptfs_printk(KERN_DEBUG,
1900                                         "Considering cadidate auth tok:\n");
1901                         ecryptfs_dump_auth_tok(candidate_auth_tok);
1902                 }
1903                 rc = ecryptfs_get_auth_tok_sig(&candidate_auth_tok_sig,
1904                                                candidate_auth_tok);
1905                 if (rc) {
1906                         printk(KERN_ERR
1907                                "Unrecognized candidate auth tok type: [%d]\n",
1908                                candidate_auth_tok->token_type);
1909                         rc = -EINVAL;
1910                         goto out_wipe_list;
1911                 }
1912                 rc = ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
1913                                                &matching_auth_tok,
1914                                                crypt_stat->mount_crypt_stat,
1915                                                candidate_auth_tok_sig);
1916                 if (!rc) {
1917                         found_auth_tok = 1;
1918                         goto found_matching_auth_tok;
1919                 }
1920         }
1921         if (!found_auth_tok) {
1922                 ecryptfs_printk(KERN_ERR, "Could not find a usable "
1923                                 "authentication token\n");
1924                 rc = -EIO;
1925                 goto out_wipe_list;
1926         }
1927 found_matching_auth_tok:
1928         if (candidate_auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
1929                 memcpy(&(candidate_auth_tok->token.private_key),
1930                        &(matching_auth_tok->token.private_key),
1931                        sizeof(struct ecryptfs_private_key));
1932                 up_write(&(auth_tok_key->sem));
1933                 key_put(auth_tok_key);
1934                 rc = decrypt_pki_encrypted_session_key(candidate_auth_tok,
1935                                                        crypt_stat);
1936         } else if (candidate_auth_tok->token_type == ECRYPTFS_PASSWORD) {
1937                 memcpy(&(candidate_auth_tok->token.password),
1938                        &(matching_auth_tok->token.password),
1939                        sizeof(struct ecryptfs_password));
1940                 up_write(&(auth_tok_key->sem));
1941                 key_put(auth_tok_key);
1942                 rc = decrypt_passphrase_encrypted_session_key(
1943                         candidate_auth_tok, crypt_stat);
1944         } else {
1945                 up_write(&(auth_tok_key->sem));
1946                 key_put(auth_tok_key);
1947                 rc = -EINVAL;
1948         }
1949         if (rc) {
1950                 struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;
1951
1952                 ecryptfs_printk(KERN_WARNING, "Error decrypting the "
1953                                 "session key for authentication token with sig "
1954                                 "[%.*s]; rc = [%d]. Removing auth tok "
1955                                 "candidate from the list and searching for "
1956                                 "the next match.\n", ECRYPTFS_SIG_SIZE_HEX,
1957                                 candidate_auth_tok_sig, rc);
1958                 list_for_each_entry_safe(auth_tok_list_item,
1959                                          auth_tok_list_item_tmp,
1960                                          &auth_tok_list, list) {
1961                         if (candidate_auth_tok
1962                             == &auth_tok_list_item->auth_tok) {
1963                                 list_del(&auth_tok_list_item->list);
1964                                 kmem_cache_free(
1965                                         ecryptfs_auth_tok_list_item_cache,
1966                                         auth_tok_list_item);
1967                                 goto find_next_matching_auth_tok;
1968                         }
1969                 }
1970                 BUG();
1971         }
1972         rc = ecryptfs_compute_root_iv(crypt_stat);
1973         if (rc) {
1974                 ecryptfs_printk(KERN_ERR, "Error computing "
1975                                 "the root IV\n");
1976                 goto out_wipe_list;
1977         }
1978         rc = ecryptfs_init_crypt_ctx(crypt_stat);
1979         if (rc) {
1980                 ecryptfs_printk(KERN_ERR, "Error initializing crypto "
1981                                 "context for cipher [%s]; rc = [%d]\n",
1982                                 crypt_stat->cipher, rc);
1983         }
1984 out_wipe_list:
1985         wipe_auth_tok_list(&auth_tok_list);
1986 out:
1987         return rc;
1988 }
1989
1990 static int
1991 pki_encrypt_session_key(struct key *auth_tok_key,
1992                         struct ecryptfs_auth_tok *auth_tok,
1993                         struct ecryptfs_crypt_stat *crypt_stat,
1994                         struct ecryptfs_key_record *key_rec)
1995 {
1996         struct ecryptfs_msg_ctx *msg_ctx = NULL;
1997         char *payload = NULL;
1998         size_t payload_len = 0;
1999         struct ecryptfs_message *msg;
2000         int rc;
2001
2002         rc = write_tag_66_packet(auth_tok->token.private_key.signature,
2003                                  ecryptfs_code_for_cipher_string(
2004                                          crypt_stat->cipher,
2005                                          crypt_stat->key_size),
2006                                  crypt_stat, &payload, &payload_len);
2007         up_write(&(auth_tok_key->sem));
2008         key_put(auth_tok_key);
2009         if (rc) {
2010                 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet\n");
2011                 goto out;
2012         }
2013         rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);
2014         if (rc) {
2015                 ecryptfs_printk(KERN_ERR, "Error sending message to "
2016                                 "ecryptfsd: %d\n", rc);
2017                 goto out;
2018         }
2019         rc = ecryptfs_wait_for_response(msg_ctx, &msg);
2020         if (rc) {
2021                 ecryptfs_printk(KERN_ERR, "Failed to receive tag 67 packet "
2022                                 "from the user space daemon\n");
2023                 rc = -EIO;
2024                 goto out;
2025         }
2026         rc = parse_tag_67_packet(key_rec, msg);
2027         if (rc)
2028                 ecryptfs_printk(KERN_ERR, "Error parsing tag 67 packet\n");
2029         kfree(msg);
2030 out:
2031         kfree(payload);
2032         return rc;
2033 }
2034 /**
2035  * write_tag_1_packet - Write an RFC2440-compatible tag 1 (public key) packet
2036  * @dest: Buffer into which to write the packet
2037  * @remaining_bytes: Maximum number of bytes that can be writtn
2038  * @auth_tok_key: The authentication token key to unlock and put when done with
2039  *                @auth_tok
2040  * @auth_tok: The authentication token used for generating the tag 1 packet
2041  * @crypt_stat: The cryptographic context
2042  * @key_rec: The key record struct for the tag 1 packet
2043  * @packet_size: This function will write the number of bytes that end
2044  *               up constituting the packet; set to zero on error
2045  *
2046  * Returns zero on success; non-zero on error.
2047  */
2048 static int
2049 write_tag_1_packet(char *dest, size_t *remaining_bytes,
2050                    struct key *auth_tok_key, struct ecryptfs_auth_tok *auth_tok,
2051                    struct ecryptfs_crypt_stat *crypt_stat,
2052                    struct ecryptfs_key_record *key_rec, size_t *packet_size)
2053 {
2054         size_t i;
2055         size_t encrypted_session_key_valid = 0;
2056         size_t packet_size_length;
2057         size_t max_packet_size;
2058         int rc = 0;
2059
2060         (*packet_size) = 0;
2061         ecryptfs_from_hex(key_rec->sig, auth_tok->token.private_key.signature,
2062                           ECRYPTFS_SIG_SIZE);
2063         encrypted_session_key_valid = 0;
2064         for (i = 0; i < crypt_stat->key_size; i++)
2065                 encrypted_session_key_valid |=
2066                         auth_tok->session_key.encrypted_key[i];
2067         if (encrypted_session_key_valid) {
2068                 memcpy(key_rec->enc_key,
2069                        auth_tok->session_key.encrypted_key,
2070                        auth_tok->session_key.encrypted_key_size);
2071                 up_write(&(auth_tok_key->sem));
2072                 key_put(auth_tok_key);
2073                 goto encrypted_session_key_set;
2074         }
2075         if (auth_tok->session_key.encrypted_key_size == 0)
2076                 auth_tok->session_key.encrypted_key_size =
2077                         auth_tok->token.private_key.key_size;
2078         rc = pki_encrypt_session_key(auth_tok_key, auth_tok, crypt_stat,
2079                                      key_rec);
2080         if (rc) {
2081                 printk(KERN_ERR "Failed to encrypt session key via a key "
2082                        "module; rc = [%d]\n", rc);
2083                 goto out;
2084         }
2085         if (ecryptfs_verbosity > 0) {
2086                 ecryptfs_printk(KERN_DEBUG, "Encrypted key:\n");
2087                 ecryptfs_dump_hex(key_rec->enc_key, key_rec->enc_key_size);
2088         }
2089 encrypted_session_key_set:
2090         /* This format is inspired by OpenPGP; see RFC 2440
2091          * packet tag 1 */
2092         max_packet_size = (1                         /* Tag 1 identifier */
2093                            + 3                       /* Max Tag 1 packet size */
2094                            + 1                       /* Version */
2095                            + ECRYPTFS_SIG_SIZE       /* Key identifier */
2096                            + 1                       /* Cipher identifier */
2097                            + key_rec->enc_key_size); /* Encrypted key size */
2098         if (max_packet_size > (*remaining_bytes)) {
2099                 printk(KERN_ERR "Packet length larger than maximum allowable; "
2100                        "need up to [%td] bytes, but there are only [%td] "
2101                        "available\n", max_packet_size, (*remaining_bytes));
2102                 rc = -EINVAL;
2103                 goto out;
2104         }
2105         dest[(*packet_size)++] = ECRYPTFS_TAG_1_PACKET_TYPE;
2106         rc = ecryptfs_write_packet_length(&dest[(*packet_size)],
2107                                           (max_packet_size - 4),
2108                                           &packet_size_length);
2109         if (rc) {
2110                 ecryptfs_printk(KERN_ERR, "Error generating tag 1 packet "
2111                                 "header; cannot generate packet length\n");
2112                 goto out;
2113         }
2114         (*packet_size) += packet_size_length;
2115         dest[(*packet_size)++] = 0x03; /* version 3 */
2116         memcpy(&dest[(*packet_size)], key_rec->sig, ECRYPTFS_SIG_SIZE);
2117         (*packet_size) += ECRYPTFS_SIG_SIZE;
2118         dest[(*packet_size)++] = RFC2440_CIPHER_RSA;
2119         memcpy(&dest[(*packet_size)], key_rec->enc_key,
2120                key_rec->enc_key_size);
2121         (*packet_size) += key_rec->enc_key_size;
2122 out:
2123         if (rc)
2124                 (*packet_size) = 0;
2125         else
2126                 (*remaining_bytes) -= (*packet_size);
2127         return rc;
2128 }
2129
2130 /**
2131  * write_tag_11_packet
2132  * @dest: Target into which Tag 11 packet is to be written
2133  * @remaining_bytes: Maximum packet length
2134  * @contents: Byte array of contents to copy in
2135  * @contents_length: Number of bytes in contents
2136  * @packet_length: Length of the Tag 11 packet written; zero on error
2137  *
2138  * Returns zero on success; non-zero on error.
2139  */
2140 static int
2141 write_tag_11_packet(char *dest, size_t *remaining_bytes, char *contents,
2142                     size_t contents_length, size_t *packet_length)
2143 {
2144         size_t packet_size_length;
2145         size_t max_packet_size;
2146         int rc = 0;
2147
2148         (*packet_length) = 0;
2149         /* This format is inspired by OpenPGP; see RFC 2440
2150          * packet tag 11 */
2151         max_packet_size = (1                   /* Tag 11 identifier */
2152                            + 3                 /* Max Tag 11 packet size */
2153                            + 1                 /* Binary format specifier */
2154                            + 1                 /* Filename length */
2155                            + 8                 /* Filename ("_CONSOLE") */
2156                            + 4                 /* Modification date */
2157                            + contents_length); /* Literal data */
2158         if (max_packet_size > (*remaining_bytes)) {
2159                 printk(KERN_ERR "Packet length larger than maximum allowable; "
2160                        "need up to [%td] bytes, but there are only [%td] "
2161                        "available\n", max_packet_size, (*remaining_bytes));
2162                 rc = -EINVAL;
2163                 goto out;
2164         }
2165         dest[(*packet_length)++] = ECRYPTFS_TAG_11_PACKET_TYPE;
2166         rc = ecryptfs_write_packet_length(&dest[(*packet_length)],
2167                                           (max_packet_size - 4),
2168                                           &packet_size_length);
2169         if (rc) {
2170                 printk(KERN_ERR "Error generating tag 11 packet header; cannot "
2171                        "generate packet length. rc = [%d]\n", rc);
2172                 goto out;
2173         }
2174         (*packet_length) += packet_size_length;
2175         dest[(*packet_length)++] = 0x62; /* binary data format specifier */
2176         dest[(*packet_length)++] = 8;
2177         memcpy(&dest[(*packet_length)], "_CONSOLE", 8);
2178         (*packet_length) += 8;
2179         memset(&dest[(*packet_length)], 0x00, 4);
2180         (*packet_length) += 4;
2181         memcpy(&dest[(*packet_length)], contents, contents_length);
2182         (*packet_length) += contents_length;
2183  out:
2184         if (rc)
2185                 (*packet_length) = 0;
2186         else
2187                 (*remaining_bytes) -= (*packet_length);
2188         return rc;
2189 }
2190
2191 /**
2192  * write_tag_3_packet
2193  * @dest: Buffer into which to write the packet
2194  * @remaining_bytes: Maximum number of bytes that can be written
2195  * @auth_tok: Authentication token
2196  * @crypt_stat: The cryptographic context
2197  * @key_rec: encrypted key
2198  * @packet_size: This function will write the number of bytes that end
2199  *               up constituting the packet; set to zero on error
2200  *
2201  * Returns zero on success; non-zero on error.
2202  */
2203 static int
2204 write_tag_3_packet(char *dest, size_t *remaining_bytes,
2205                    struct ecryptfs_auth_tok *auth_tok,
2206                    struct ecryptfs_crypt_stat *crypt_stat,
2207                    struct ecryptfs_key_record *key_rec, size_t *packet_size)
2208 {
2209         size_t i;
2210         size_t encrypted_session_key_valid = 0;
2211         char session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES];
2212         struct scatterlist dst_sg[2];
2213         struct scatterlist src_sg[2];
2214         struct mutex *tfm_mutex = NULL;
2215         u8 cipher_code;
2216         size_t packet_size_length;
2217         size_t max_packet_size;
2218         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2219                 crypt_stat->mount_crypt_stat;
2220         struct crypto_skcipher *tfm;
2221         struct skcipher_request *req;
2222         int rc = 0;
2223
2224         (*packet_size) = 0;
2225         ecryptfs_from_hex(key_rec->sig, auth_tok->token.password.signature,
2226                           ECRYPTFS_SIG_SIZE);
2227         rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&tfm, &tfm_mutex,
2228                                                         crypt_stat->cipher);
2229         if (unlikely(rc)) {
2230                 printk(KERN_ERR "Internal error whilst attempting to get "
2231                        "tfm and mutex for cipher name [%s]; rc = [%d]\n",
2232                        crypt_stat->cipher, rc);
2233                 goto out;
2234         }
2235         if (mount_crypt_stat->global_default_cipher_key_size == 0) {
2236                 printk(KERN_WARNING "No key size specified at mount; "
2237                        "defaulting to [%d]\n",
2238                        crypto_skcipher_default_keysize(tfm));
2239                 mount_crypt_stat->global_default_cipher_key_size =
2240                         crypto_skcipher_default_keysize(tfm);
2241         }
2242         if (crypt_stat->key_size == 0)
2243                 crypt_stat->key_size =
2244                         mount_crypt_stat->global_default_cipher_key_size;
2245         if (auth_tok->session_key.encrypted_key_size == 0)
2246                 auth_tok->session_key.encrypted_key_size =
2247                         crypt_stat->key_size;
2248         if (crypt_stat->key_size == 24
2249             && strcmp("aes", crypt_stat->cipher) == 0) {
2250                 memset((crypt_stat->key + 24), 0, 8);
2251                 auth_tok->session_key.encrypted_key_size = 32;
2252         } else
2253                 auth_tok->session_key.encrypted_key_size = crypt_stat->key_size;
2254         key_rec->enc_key_size =
2255                 auth_tok->session_key.encrypted_key_size;
2256         encrypted_session_key_valid = 0;
2257         for (i = 0; i < auth_tok->session_key.encrypted_key_size; i++)
2258                 encrypted_session_key_valid |=
2259                         auth_tok->session_key.encrypted_key[i];
2260         if (encrypted_session_key_valid) {
2261                 ecryptfs_printk(KERN_DEBUG, "encrypted_session_key_valid != 0; "
2262                                 "using auth_tok->session_key.encrypted_key, "
2263                                 "where key_rec->enc_key_size = [%zd]\n",
2264                                 key_rec->enc_key_size);
2265                 memcpy(key_rec->enc_key,
2266                        auth_tok->session_key.encrypted_key,
2267                        key_rec->enc_key_size);
2268                 goto encrypted_session_key_set;
2269         }
2270         if (auth_tok->token.password.flags &
2271             ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET) {
2272                 ecryptfs_printk(KERN_DEBUG, "Using previously generated "
2273                                 "session key encryption key of size [%d]\n",
2274                                 auth_tok->token.password.
2275                                 session_key_encryption_key_bytes);
2276                 memcpy(session_key_encryption_key,
2277                        auth_tok->token.password.session_key_encryption_key,
2278                        crypt_stat->key_size);
2279                 ecryptfs_printk(KERN_DEBUG,
2280                                 "Cached session key encryption key:\n");
2281                 if (ecryptfs_verbosity > 0)
2282                         ecryptfs_dump_hex(session_key_encryption_key, 16);
2283         }
2284         if (unlikely(ecryptfs_verbosity > 0)) {
2285                 ecryptfs_printk(KERN_DEBUG, "Session key encryption key:\n");
2286                 ecryptfs_dump_hex(session_key_encryption_key, 16);
2287         }
2288         rc = virt_to_scatterlist(crypt_stat->key, key_rec->enc_key_size,
2289                                  src_sg, 2);
2290         if (rc < 1 || rc > 2) {
2291                 ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
2292                                 "for crypt_stat session key; expected rc = 1; "
2293                                 "got rc = [%d]. key_rec->enc_key_size = [%zd]\n",
2294                                 rc, key_rec->enc_key_size);
2295                 rc = -ENOMEM;
2296                 goto out;
2297         }
2298         rc = virt_to_scatterlist(key_rec->enc_key, key_rec->enc_key_size,
2299                                  dst_sg, 2);
2300         if (rc < 1 || rc > 2) {
2301                 ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
2302                                 "for crypt_stat encrypted session key; "
2303                                 "expected rc = 1; got rc = [%d]. "
2304                                 "key_rec->enc_key_size = [%zd]\n", rc,
2305                                 key_rec->enc_key_size);
2306                 rc = -ENOMEM;
2307                 goto out;
2308         }
2309         mutex_lock(tfm_mutex);
2310         rc = crypto_skcipher_setkey(tfm, session_key_encryption_key,
2311                                     crypt_stat->key_size);
2312         if (rc < 0) {
2313                 mutex_unlock(tfm_mutex);
2314                 ecryptfs_printk(KERN_ERR, "Error setting key for crypto "
2315                                 "context; rc = [%d]\n", rc);
2316                 goto out;
2317         }
2318
2319         req = skcipher_request_alloc(tfm, GFP_KERNEL);
2320         if (!req) {
2321                 mutex_unlock(tfm_mutex);
2322                 ecryptfs_printk(KERN_ERR, "Out of kernel memory whilst "
2323                                 "attempting to skcipher_request_alloc for "
2324                                 "%s\n", crypto_skcipher_driver_name(tfm));
2325                 rc = -ENOMEM;
2326                 goto out;
2327         }
2328
2329         skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_SLEEP,
2330                                       NULL, NULL);
2331
2332         rc = 0;
2333         ecryptfs_printk(KERN_DEBUG, "Encrypting [%zd] bytes of the key\n",
2334                         crypt_stat->key_size);
2335         skcipher_request_set_crypt(req, src_sg, dst_sg,
2336                                    (*key_rec).enc_key_size, NULL);
2337         rc = crypto_skcipher_encrypt(req);
2338         mutex_unlock(tfm_mutex);
2339         skcipher_request_free(req);
2340         if (rc) {
2341                 printk(KERN_ERR "Error encrypting; rc = [%d]\n", rc);
2342                 goto out;
2343         }
2344         ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n");
2345         if (ecryptfs_verbosity > 0) {
2346                 ecryptfs_printk(KERN_DEBUG, "EFEK of size [%zd]:\n",
2347                                 key_rec->enc_key_size);
2348                 ecryptfs_dump_hex(key_rec->enc_key,
2349                                   key_rec->enc_key_size);
2350         }
2351 encrypted_session_key_set:
2352         /* This format is inspired by OpenPGP; see RFC 2440
2353          * packet tag 3 */
2354         max_packet_size = (1                         /* Tag 3 identifier */
2355                            + 3                       /* Max Tag 3 packet size */
2356                            + 1                       /* Version */
2357                            + 1                       /* Cipher code */
2358                            + 1                       /* S2K specifier */
2359                            + 1                       /* Hash identifier */
2360                            + ECRYPTFS_SALT_SIZE      /* Salt */
2361                            + 1                       /* Hash iterations */
2362                            + key_rec->enc_key_size); /* Encrypted key size */
2363         if (max_packet_size > (*remaining_bytes)) {
2364                 printk(KERN_ERR "Packet too large; need up to [%td] bytes, but "
2365                        "there are only [%td] available\n", max_packet_size,
2366                        (*remaining_bytes));
2367                 rc = -EINVAL;
2368                 goto out;
2369         }
2370         dest[(*packet_size)++] = ECRYPTFS_TAG_3_PACKET_TYPE;
2371         /* Chop off the Tag 3 identifier(1) and Tag 3 packet size(3)
2372          * to get the number of octets in the actual Tag 3 packet */
2373         rc = ecryptfs_write_packet_length(&dest[(*packet_size)],
2374                                           (max_packet_size - 4),
2375                                           &packet_size_length);
2376         if (rc) {
2377                 printk(KERN_ERR "Error generating tag 3 packet header; cannot "
2378                        "generate packet length. rc = [%d]\n", rc);
2379                 goto out;
2380         }
2381         (*packet_size) += packet_size_length;
2382         dest[(*packet_size)++] = 0x04; /* version 4 */
2383         /* TODO: Break from RFC2440 so that arbitrary ciphers can be
2384          * specified with strings */
2385         cipher_code = ecryptfs_code_for_cipher_string(crypt_stat->cipher,
2386                                                       crypt_stat->key_size);
2387         if (cipher_code == 0) {
2388                 ecryptfs_printk(KERN_WARNING, "Unable to generate code for "
2389                                 "cipher [%s]\n", crypt_stat->cipher);
2390                 rc = -EINVAL;
2391                 goto out;
2392         }
2393         dest[(*packet_size)++] = cipher_code;
2394         dest[(*packet_size)++] = 0x03;  /* S2K */
2395         dest[(*packet_size)++] = 0x01;  /* MD5 (TODO: parameterize) */
2396         memcpy(&dest[(*packet_size)], auth_tok->token.password.salt,
2397                ECRYPTFS_SALT_SIZE);
2398         (*packet_size) += ECRYPTFS_SALT_SIZE;   /* salt */
2399         dest[(*packet_size)++] = 0x60;  /* hash iterations (65536) */
2400         memcpy(&dest[(*packet_size)], key_rec->enc_key,
2401                key_rec->enc_key_size);
2402         (*packet_size) += key_rec->enc_key_size;
2403 out:
2404         if (rc)
2405                 (*packet_size) = 0;
2406         else
2407                 (*remaining_bytes) -= (*packet_size);
2408         return rc;
2409 }
2410
2411 struct kmem_cache *ecryptfs_key_record_cache;
2412
2413 /**
2414  * ecryptfs_generate_key_packet_set
2415  * @dest_base: Virtual address from which to write the key record set
2416  * @crypt_stat: The cryptographic context from which the
2417  *              authentication tokens will be retrieved
2418  * @ecryptfs_dentry: The dentry, used to retrieve the mount crypt stat
2419  *                   for the global parameters
2420  * @len: The amount written
2421  * @max: The maximum amount of data allowed to be written
2422  *
2423  * Generates a key packet set and writes it to the virtual address
2424  * passed in.
2425  *
2426  * Returns zero on success; non-zero on error.
2427  */
2428 int
2429 ecryptfs_generate_key_packet_set(char *dest_base,
2430                                  struct ecryptfs_crypt_stat *crypt_stat,
2431                                  struct dentry *ecryptfs_dentry, size_t *len,
2432                                  size_t max)
2433 {
2434         struct ecryptfs_auth_tok *auth_tok;
2435         struct key *auth_tok_key = NULL;
2436         struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
2437                 &ecryptfs_superblock_to_private(
2438                         ecryptfs_dentry->d_sb)->mount_crypt_stat;
2439         size_t written;
2440         struct ecryptfs_key_record *key_rec;
2441         struct ecryptfs_key_sig *key_sig;
2442         int rc = 0;
2443
2444         (*len) = 0;
2445         mutex_lock(&crypt_stat->keysig_list_mutex);
2446         key_rec = kmem_cache_alloc(ecryptfs_key_record_cache, GFP_KERNEL);
2447         if (!key_rec) {
2448                 rc = -ENOMEM;
2449                 goto out;
2450         }
2451         list_for_each_entry(key_sig, &crypt_stat->keysig_list,
2452                             crypt_stat_list) {
2453                 memset(key_rec, 0, sizeof(*key_rec));
2454                 rc = ecryptfs_find_global_auth_tok_for_sig(&auth_tok_key,
2455                                                            &auth_tok,
2456                                                            mount_crypt_stat,
2457                                                            key_sig->keysig);
2458                 if (rc) {
2459                         printk(KERN_WARNING "Unable to retrieve auth tok with "
2460                                "sig = [%s]\n", key_sig->keysig);
2461                         rc = process_find_global_auth_tok_for_sig_err(rc);
2462                         goto out_free;
2463                 }
2464                 if (auth_tok->token_type == ECRYPTFS_PASSWORD) {
2465                         rc = write_tag_3_packet((dest_base + (*len)),
2466                                                 &max, auth_tok,
2467                                                 crypt_stat, key_rec,
2468                                                 &written);
2469                         up_write(&(auth_tok_key->sem));
2470                         key_put(auth_tok_key);
2471                         if (rc) {
2472                                 ecryptfs_printk(KERN_WARNING, "Error "
2473                                                 "writing tag 3 packet\n");
2474                                 goto out_free;
2475                         }
2476                         (*len) += written;
2477                         /* Write auth tok signature packet */
2478                         rc = write_tag_11_packet((dest_base + (*len)), &max,
2479                                                  key_rec->sig,
2480                                                  ECRYPTFS_SIG_SIZE, &written);
2481                         if (rc) {
2482                                 ecryptfs_printk(KERN_ERR, "Error writing "
2483                                                 "auth tok signature packet\n");
2484                                 goto out_free;
2485                         }
2486                         (*len) += written;
2487                 } else if (auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
2488                         rc = write_tag_1_packet(dest_base + (*len), &max,
2489                                                 auth_tok_key, auth_tok,
2490                                                 crypt_stat, key_rec, &written);
2491                         if (rc) {
2492                                 ecryptfs_printk(KERN_WARNING, "Error "
2493                                                 "writing tag 1 packet\n");
2494                                 goto out_free;
2495                         }
2496                         (*len) += written;
2497                 } else {
2498                         up_write(&(auth_tok_key->sem));
2499                         key_put(auth_tok_key);
2500                         ecryptfs_printk(KERN_WARNING, "Unsupported "
2501                                         "authentication token type\n");
2502                         rc = -EINVAL;
2503                         goto out_free;
2504                 }
2505         }
2506         if (likely(max > 0)) {
2507                 dest_base[(*len)] = 0x00;
2508         } else {
2509                 ecryptfs_printk(KERN_ERR, "Error writing boundary byte\n");
2510                 rc = -EIO;
2511         }
2512 out_free:
2513         kmem_cache_free(ecryptfs_key_record_cache, key_rec);
2514 out:
2515         if (rc)
2516                 (*len) = 0;
2517         mutex_unlock(&crypt_stat->keysig_list_mutex);
2518         return rc;
2519 }
2520
2521 struct kmem_cache *ecryptfs_key_sig_cache;
2522
2523 int ecryptfs_add_keysig(struct ecryptfs_crypt_stat *crypt_stat, char *sig)
2524 {
2525         struct ecryptfs_key_sig *new_key_sig;
2526
2527         new_key_sig = kmem_cache_alloc(ecryptfs_key_sig_cache, GFP_KERNEL);
2528         if (!new_key_sig) {
2529                 printk(KERN_ERR
2530                        "Error allocating from ecryptfs_key_sig_cache\n");
2531                 return -ENOMEM;
2532         }
2533         memcpy(new_key_sig->keysig, sig, ECRYPTFS_SIG_SIZE_HEX);
2534         new_key_sig->keysig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
2535         /* Caller must hold keysig_list_mutex */
2536         list_add(&new_key_sig->crypt_stat_list, &crypt_stat->keysig_list);
2537
2538         return 0;
2539 }
2540
2541 struct kmem_cache *ecryptfs_global_auth_tok_cache;
2542
2543 int
2544 ecryptfs_add_global_auth_tok(struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
2545                              char *sig, u32 global_auth_tok_flags)
2546 {
2547         struct ecryptfs_global_auth_tok *new_auth_tok;
2548         int rc = 0;
2549
2550         new_auth_tok = kmem_cache_zalloc(ecryptfs_global_auth_tok_cache,
2551                                         GFP_KERNEL);
2552         if (!new_auth_tok) {
2553                 rc = -ENOMEM;
2554                 printk(KERN_ERR "Error allocating from "
2555                        "ecryptfs_global_auth_tok_cache\n");
2556                 goto out;
2557         }
2558         memcpy(new_auth_tok->sig, sig, ECRYPTFS_SIG_SIZE_HEX);
2559         new_auth_tok->flags = global_auth_tok_flags;
2560         new_auth_tok->sig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
2561         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
2562         list_add(&new_auth_tok->mount_crypt_stat_list,
2563                  &mount_crypt_stat->global_auth_tok_list);
2564         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
2565 out:
2566         return rc;
2567 }
2568