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1/*
2 * Copyright (C) 2010 IBM Corporation
3 * Copyright (C) 2010 Politecnico di Torino, Italy
4 * TORSEC group -- http://security.polito.it
5 *
6 * Authors:
7 * Mimi Zohar <zohar@us.ibm.com>
8 * Roberto Sassu <roberto.sassu@polito.it>
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation, version 2 of the License.
13 *
14 * See Documentation/security/keys-trusted-encrypted.txt
15 */
16
17#include <linux/uaccess.h>
18#include <linux/module.h>
19#include <linux/init.h>
20#include <linux/slab.h>
21#include <linux/parser.h>
22#include <linux/string.h>
23#include <linux/err.h>
24#include <keys/user-type.h>
25#include <keys/trusted-type.h>
26#include <keys/encrypted-type.h>
27#include <linux/key-type.h>
28#include <linux/random.h>
29#include <linux/rcupdate.h>
30#include <linux/scatterlist.h>
31#include <linux/crypto.h>
32#include <linux/ctype.h>
33#include <crypto/hash.h>
34#include <crypto/sha.h>
35#include <crypto/aes.h>
36
37#include "encrypted.h"
38#include "ecryptfs_format.h"
39
40static const char KEY_TRUSTED_PREFIX[] = "trusted:";
41static const char KEY_USER_PREFIX[] = "user:";
42static const char hash_alg[] = "sha256";
43static const char hmac_alg[] = "hmac(sha256)";
44static const char blkcipher_alg[] = "cbc(aes)";
45static const char key_format_default[] = "default";
46static const char key_format_ecryptfs[] = "ecryptfs";
47static unsigned int ivsize;
48static int blksize;
49
50#define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1)
51#define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1)
52#define KEY_ECRYPTFS_DESC_LEN 16
53#define HASH_SIZE SHA256_DIGEST_SIZE
54#define MAX_DATA_SIZE 4096
55#define MIN_DATA_SIZE 20
56
57struct sdesc {
58 struct shash_desc shash;
59 char ctx[];
60};
61
62static struct crypto_shash *hashalg;
63static struct crypto_shash *hmacalg;
64
65enum {
66 Opt_err = -1, Opt_new, Opt_load, Opt_update
67};
68
69enum {
70 Opt_error = -1, Opt_default, Opt_ecryptfs
71};
72
73static const match_table_t key_format_tokens = {
74 {Opt_default, "default"},
75 {Opt_ecryptfs, "ecryptfs"},
76 {Opt_error, NULL}
77};
78
79static const match_table_t key_tokens = {
80 {Opt_new, "new"},
81 {Opt_load, "load"},
82 {Opt_update, "update"},
83 {Opt_err, NULL}
84};
85
86static int aes_get_sizes(void)
87{
88 struct crypto_blkcipher *tfm;
89
90 tfm = crypto_alloc_blkcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
91 if (IS_ERR(tfm)) {
92 pr_err("encrypted_key: failed to alloc_cipher (%ld)\n",
93 PTR_ERR(tfm));
94 return PTR_ERR(tfm);
95 }
96 ivsize = crypto_blkcipher_ivsize(tfm);
97 blksize = crypto_blkcipher_blocksize(tfm);
98 crypto_free_blkcipher(tfm);
99 return 0;
100}
101
102/*
103 * valid_ecryptfs_desc - verify the description of a new/loaded encrypted key
104 *
105 * The description of a encrypted key with format 'ecryptfs' must contain
106 * exactly 16 hexadecimal characters.
107 *
108 */
109static int valid_ecryptfs_desc(const char *ecryptfs_desc)
110{
111 int i;
112
113 if (strlen(ecryptfs_desc) != KEY_ECRYPTFS_DESC_LEN) {
114 pr_err("encrypted_key: key description must be %d hexadecimal "
115 "characters long\n", KEY_ECRYPTFS_DESC_LEN);
116 return -EINVAL;
117 }
118
119 for (i = 0; i < KEY_ECRYPTFS_DESC_LEN; i++) {
120 if (!isxdigit(ecryptfs_desc[i])) {
121 pr_err("encrypted_key: key description must contain "
122 "only hexadecimal characters\n");
123 return -EINVAL;
124 }
125 }
126
127 return 0;
128}
129
130/*
131 * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key
132 *
133 * key-type:= "trusted:" | "user:"
134 * desc:= master-key description
135 *
136 * Verify that 'key-type' is valid and that 'desc' exists. On key update,
137 * only the master key description is permitted to change, not the key-type.
138 * The key-type remains constant.
139 *
140 * On success returns 0, otherwise -EINVAL.
141 */
142static int valid_master_desc(const char *new_desc, const char *orig_desc)
143{
144 if (!memcmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) {
145 if (strlen(new_desc) == KEY_TRUSTED_PREFIX_LEN)
146 goto out;
147 if (orig_desc)
148 if (memcmp(new_desc, orig_desc, KEY_TRUSTED_PREFIX_LEN))
149 goto out;
150 } else if (!memcmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) {
151 if (strlen(new_desc) == KEY_USER_PREFIX_LEN)
152 goto out;
153 if (orig_desc)
154 if (memcmp(new_desc, orig_desc, KEY_USER_PREFIX_LEN))
155 goto out;
156 } else
157 goto out;
158 return 0;
159out:
160 return -EINVAL;
161}
162
163/*
164 * datablob_parse - parse the keyctl data
165 *
166 * datablob format:
167 * new [<format>] <master-key name> <decrypted data length>
168 * load [<format>] <master-key name> <decrypted data length>
169 * <encrypted iv + data>
170 * update <new-master-key name>
171 *
172 * Tokenizes a copy of the keyctl data, returning a pointer to each token,
173 * which is null terminated.
174 *
175 * On success returns 0, otherwise -EINVAL.
176 */
177static int datablob_parse(char *datablob, const char **format,
178 char **master_desc, char **decrypted_datalen,
179 char **hex_encoded_iv)
180{
181 substring_t args[MAX_OPT_ARGS];
182 int ret = -EINVAL;
183 int key_cmd;
184 int key_format;
185 char *p, *keyword;
186
187 keyword = strsep(&datablob, " \t");
188 if (!keyword) {
189 pr_info("encrypted_key: insufficient parameters specified\n");
190 return ret;
191 }
192 key_cmd = match_token(keyword, key_tokens, args);
193
194 /* Get optional format: default | ecryptfs */
195 p = strsep(&datablob, " \t");
196 if (!p) {
197 pr_err("encrypted_key: insufficient parameters specified\n");
198 return ret;
199 }
200
201 key_format = match_token(p, key_format_tokens, args);
202 switch (key_format) {
203 case Opt_ecryptfs:
204 case Opt_default:
205 *format = p;
206 *master_desc = strsep(&datablob, " \t");
207 break;
208 case Opt_error:
209 *master_desc = p;
210 break;
211 }
212
213 if (!*master_desc) {
214 pr_info("encrypted_key: master key parameter is missing\n");
215 goto out;
216 }
217
218 if (valid_master_desc(*master_desc, NULL) < 0) {
219 pr_info("encrypted_key: master key parameter \'%s\' "
220 "is invalid\n", *master_desc);
221 goto out;
222 }
223
224 if (decrypted_datalen) {
225 *decrypted_datalen = strsep(&datablob, " \t");
226 if (!*decrypted_datalen) {
227 pr_info("encrypted_key: keylen parameter is missing\n");
228 goto out;
229 }
230 }
231
232 switch (key_cmd) {
233 case Opt_new:
234 if (!decrypted_datalen) {
235 pr_info("encrypted_key: keyword \'%s\' not allowed "
236 "when called from .update method\n", keyword);
237 break;
238 }
239 ret = 0;
240 break;
241 case Opt_load:
242 if (!decrypted_datalen) {
243 pr_info("encrypted_key: keyword \'%s\' not allowed "
244 "when called from .update method\n", keyword);
245 break;
246 }
247 *hex_encoded_iv = strsep(&datablob, " \t");
248 if (!*hex_encoded_iv) {
249 pr_info("encrypted_key: hex blob is missing\n");
250 break;
251 }
252 ret = 0;
253 break;
254 case Opt_update:
255 if (decrypted_datalen) {
256 pr_info("encrypted_key: keyword \'%s\' not allowed "
257 "when called from .instantiate method\n",
258 keyword);
259 break;
260 }
261 ret = 0;
262 break;
263 case Opt_err:
264 pr_info("encrypted_key: keyword \'%s\' not recognized\n",
265 keyword);
266 break;
267 }
268out:
269 return ret;
270}
271
272/*
273 * datablob_format - format as an ascii string, before copying to userspace
274 */
275static char *datablob_format(struct encrypted_key_payload *epayload,
276 size_t asciiblob_len)
277{
278 char *ascii_buf, *bufp;
279 u8 *iv = epayload->iv;
280 int len;
281 int i;
282
283 ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL);
284 if (!ascii_buf)
285 goto out;
286
287 ascii_buf[asciiblob_len] = '\0';
288
289 /* copy datablob master_desc and datalen strings */
290 len = sprintf(ascii_buf, "%s %s %s ", epayload->format,
291 epayload->master_desc, epayload->datalen);
292
293 /* convert the hex encoded iv, encrypted-data and HMAC to ascii */
294 bufp = &ascii_buf[len];
295 for (i = 0; i < (asciiblob_len - len) / 2; i++)
296 bufp = pack_hex_byte(bufp, iv[i]);
297out:
298 return ascii_buf;
299}
300
301/*
302 * request_trusted_key - request the trusted key
303 *
304 * Trusted keys are sealed to PCRs and other metadata. Although userspace
305 * manages both trusted/encrypted key-types, like the encrypted key type
306 * data, trusted key type data is not visible decrypted from userspace.
307 */
308static struct key *request_trusted_key(const char *trusted_desc,
309 u8 **master_key, size_t *master_keylen)
310{
311 struct trusted_key_payload *tpayload;
312 struct key *tkey;
313
314 tkey = request_key(&key_type_trusted, trusted_desc, NULL);
315 if (IS_ERR(tkey))
316 goto error;
317
318 down_read(&tkey->sem);
319 tpayload = rcu_dereference(tkey->payload.data);
320 *master_key = tpayload->key;
321 *master_keylen = tpayload->key_len;
322error:
323 return tkey;
324}
325
326/*
327 * request_user_key - request the user key
328 *
329 * Use a user provided key to encrypt/decrypt an encrypted-key.
330 */
331static struct key *request_user_key(const char *master_desc, u8 **master_key,
332 size_t *master_keylen)
333{
334 struct user_key_payload *upayload;
335 struct key *ukey;
336
337 ukey = request_key(&key_type_user, master_desc, NULL);
338 if (IS_ERR(ukey))
339 goto error;
340
341 down_read(&ukey->sem);
342 upayload = rcu_dereference(ukey->payload.data);
343 *master_key = upayload->data;
344 *master_keylen = upayload->datalen;
345error:
346 return ukey;
347}
348
349static struct sdesc *alloc_sdesc(struct crypto_shash *alg)
350{
351 struct sdesc *sdesc;
352 int size;
353
354 size = sizeof(struct shash_desc) + crypto_shash_descsize(alg);
355 sdesc = kmalloc(size, GFP_KERNEL);
356 if (!sdesc)
357 return ERR_PTR(-ENOMEM);
358 sdesc->shash.tfm = alg;
359 sdesc->shash.flags = 0x0;
360 return sdesc;
361}
362
363static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen,
364 const u8 *buf, unsigned int buflen)
365{
366 struct sdesc *sdesc;
367 int ret;
368
369 sdesc = alloc_sdesc(hmacalg);
370 if (IS_ERR(sdesc)) {
371 pr_info("encrypted_key: can't alloc %s\n", hmac_alg);
372 return PTR_ERR(sdesc);
373 }
374
375 ret = crypto_shash_setkey(hmacalg, key, keylen);
376 if (!ret)
377 ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
378 kfree(sdesc);
379 return ret;
380}
381
382static int calc_hash(u8 *digest, const u8 *buf, unsigned int buflen)
383{
384 struct sdesc *sdesc;
385 int ret;
386
387 sdesc = alloc_sdesc(hashalg);
388 if (IS_ERR(sdesc)) {
389 pr_info("encrypted_key: can't alloc %s\n", hash_alg);
390 return PTR_ERR(sdesc);
391 }
392
393 ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
394 kfree(sdesc);
395 return ret;
396}
397
398enum derived_key_type { ENC_KEY, AUTH_KEY };
399
400/* Derive authentication/encryption key from trusted key */
401static int get_derived_key(u8 *derived_key, enum derived_key_type key_type,
402 const u8 *master_key, size_t master_keylen)
403{
404 u8 *derived_buf;
405 unsigned int derived_buf_len;
406 int ret;
407
408 derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen;
409 if (derived_buf_len < HASH_SIZE)
410 derived_buf_len = HASH_SIZE;
411
412 derived_buf = kzalloc(derived_buf_len, GFP_KERNEL);
413 if (!derived_buf) {
414 pr_err("encrypted_key: out of memory\n");
415 return -ENOMEM;
416 }
417 if (key_type)
418 strcpy(derived_buf, "AUTH_KEY");
419 else
420 strcpy(derived_buf, "ENC_KEY");
421
422 memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
423 master_keylen);
424 ret = calc_hash(derived_key, derived_buf, derived_buf_len);
425 kfree(derived_buf);
426 return ret;
427}
428
429static int init_blkcipher_desc(struct blkcipher_desc *desc, const u8 *key,
430 unsigned int key_len, const u8 *iv,
431 unsigned int ivsize)
432{
433 int ret;
434
435 desc->tfm = crypto_alloc_blkcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
436 if (IS_ERR(desc->tfm)) {
437 pr_err("encrypted_key: failed to load %s transform (%ld)\n",
438 blkcipher_alg, PTR_ERR(desc->tfm));
439 return PTR_ERR(desc->tfm);
440 }
441 desc->flags = 0;
442
443 ret = crypto_blkcipher_setkey(desc->tfm, key, key_len);
444 if (ret < 0) {
445 pr_err("encrypted_key: failed to setkey (%d)\n", ret);
446 crypto_free_blkcipher(desc->tfm);
447 return ret;
448 }
449 crypto_blkcipher_set_iv(desc->tfm, iv, ivsize);
450 return 0;
451}
452
453static struct key *request_master_key(struct encrypted_key_payload *epayload,
454 u8 **master_key, size_t *master_keylen)
455{
456 struct key *mkey = NULL;
457
458 if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX,
459 KEY_TRUSTED_PREFIX_LEN)) {
460 mkey = request_trusted_key(epayload->master_desc +
461 KEY_TRUSTED_PREFIX_LEN,
462 master_key, master_keylen);
463 } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX,
464 KEY_USER_PREFIX_LEN)) {
465 mkey = request_user_key(epayload->master_desc +
466 KEY_USER_PREFIX_LEN,
467 master_key, master_keylen);
468 } else
469 goto out;
470
471 if (IS_ERR(mkey)) {
472 pr_info("encrypted_key: key %s not found",
473 epayload->master_desc);
474 goto out;
475 }
476
477 dump_master_key(*master_key, *master_keylen);
478out:
479 return mkey;
480}
481
482/* Before returning data to userspace, encrypt decrypted data. */
483static int derived_key_encrypt(struct encrypted_key_payload *epayload,
484 const u8 *derived_key,
485 unsigned int derived_keylen)
486{
487 struct scatterlist sg_in[2];
488 struct scatterlist sg_out[1];
489 struct blkcipher_desc desc;
490 unsigned int encrypted_datalen;
491 unsigned int padlen;
492 char pad[16];
493 int ret;
494
495 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
496 padlen = encrypted_datalen - epayload->decrypted_datalen;
497
498 ret = init_blkcipher_desc(&desc, derived_key, derived_keylen,
499 epayload->iv, ivsize);
500 if (ret < 0)
501 goto out;
502 dump_decrypted_data(epayload);
503
504 memset(pad, 0, sizeof pad);
505 sg_init_table(sg_in, 2);
506 sg_set_buf(&sg_in[0], epayload->decrypted_data,
507 epayload->decrypted_datalen);
508 sg_set_buf(&sg_in[1], pad, padlen);
509
510 sg_init_table(sg_out, 1);
511 sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
512
513 ret = crypto_blkcipher_encrypt(&desc, sg_out, sg_in, encrypted_datalen);
514 crypto_free_blkcipher(desc.tfm);
515 if (ret < 0)
516 pr_err("encrypted_key: failed to encrypt (%d)\n", ret);
517 else
518 dump_encrypted_data(epayload, encrypted_datalen);
519out:
520 return ret;
521}
522
523static int datablob_hmac_append(struct encrypted_key_payload *epayload,
524 const u8 *master_key, size_t master_keylen)
525{
526 u8 derived_key[HASH_SIZE];
527 u8 *digest;
528 int ret;
529
530 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
531 if (ret < 0)
532 goto out;
533
534 digest = epayload->format + epayload->datablob_len;
535 ret = calc_hmac(digest, derived_key, sizeof derived_key,
536 epayload->format, epayload->datablob_len);
537 if (!ret)
538 dump_hmac(NULL, digest, HASH_SIZE);
539out:
540 return ret;
541}
542
543/* verify HMAC before decrypting encrypted key */
544static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
545 const u8 *format, const u8 *master_key,
546 size_t master_keylen)
547{
548 u8 derived_key[HASH_SIZE];
549 u8 digest[HASH_SIZE];
550 int ret;
551 char *p;
552 unsigned short len;
553
554 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
555 if (ret < 0)
556 goto out;
557
558 len = epayload->datablob_len;
559 if (!format) {
560 p = epayload->master_desc;
561 len -= strlen(epayload->format) + 1;
562 } else
563 p = epayload->format;
564
565 ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len);
566 if (ret < 0)
567 goto out;
568 ret = memcmp(digest, epayload->format + epayload->datablob_len,
569 sizeof digest);
570 if (ret) {
571 ret = -EINVAL;
572 dump_hmac("datablob",
573 epayload->format + epayload->datablob_len,
574 HASH_SIZE);
575 dump_hmac("calc", digest, HASH_SIZE);
576 }
577out:
578 return ret;
579}
580
581static int derived_key_decrypt(struct encrypted_key_payload *epayload,
582 const u8 *derived_key,
583 unsigned int derived_keylen)
584{
585 struct scatterlist sg_in[1];
586 struct scatterlist sg_out[2];
587 struct blkcipher_desc desc;
588 unsigned int encrypted_datalen;
589 char pad[16];
590 int ret;
591
592 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
593 ret = init_blkcipher_desc(&desc, derived_key, derived_keylen,
594 epayload->iv, ivsize);
595 if (ret < 0)
596 goto out;
597 dump_encrypted_data(epayload, encrypted_datalen);
598
599 memset(pad, 0, sizeof pad);
600 sg_init_table(sg_in, 1);
601 sg_init_table(sg_out, 2);
602 sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen);
603 sg_set_buf(&sg_out[0], epayload->decrypted_data,
604 epayload->decrypted_datalen);
605 sg_set_buf(&sg_out[1], pad, sizeof pad);
606
607 ret = crypto_blkcipher_decrypt(&desc, sg_out, sg_in, encrypted_datalen);
608 crypto_free_blkcipher(desc.tfm);
609 if (ret < 0)
610 goto out;
611 dump_decrypted_data(epayload);
612out:
613 return ret;
614}
615
616/* Allocate memory for decrypted key and datablob. */
617static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
618 const char *format,
619 const char *master_desc,
620 const char *datalen)
621{
622 struct encrypted_key_payload *epayload = NULL;
623 unsigned short datablob_len;
624 unsigned short decrypted_datalen;
625 unsigned short payload_datalen;
626 unsigned int encrypted_datalen;
627 unsigned int format_len;
628 long dlen;
629 int ret;
630
631 ret = strict_strtol(datalen, 10, &dlen);
632 if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE)
633 return ERR_PTR(-EINVAL);
634
635 format_len = (!format) ? strlen(key_format_default) : strlen(format);
636 decrypted_datalen = dlen;
637 payload_datalen = decrypted_datalen;
638 if (format && !strcmp(format, key_format_ecryptfs)) {
639 if (dlen != ECRYPTFS_MAX_KEY_BYTES) {
640 pr_err("encrypted_key: keylen for the ecryptfs format "
641 "must be equal to %d bytes\n",
642 ECRYPTFS_MAX_KEY_BYTES);
643 return ERR_PTR(-EINVAL);
644 }
645 decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES;
646 payload_datalen = sizeof(struct ecryptfs_auth_tok);
647 }
648
649 encrypted_datalen = roundup(decrypted_datalen, blksize);
650
651 datablob_len = format_len + 1 + strlen(master_desc) + 1
652 + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen;
653
654 ret = key_payload_reserve(key, payload_datalen + datablob_len
655 + HASH_SIZE + 1);
656 if (ret < 0)
657 return ERR_PTR(ret);
658
659 epayload = kzalloc(sizeof(*epayload) + payload_datalen +
660 datablob_len + HASH_SIZE + 1, GFP_KERNEL);
661 if (!epayload)
662 return ERR_PTR(-ENOMEM);
663
664 epayload->payload_datalen = payload_datalen;
665 epayload->decrypted_datalen = decrypted_datalen;
666 epayload->datablob_len = datablob_len;
667 return epayload;
668}
669
670static int encrypted_key_decrypt(struct encrypted_key_payload *epayload,
671 const char *format, const char *hex_encoded_iv)
672{
673 struct key *mkey;
674 u8 derived_key[HASH_SIZE];
675 u8 *master_key;
676 u8 *hmac;
677 const char *hex_encoded_data;
678 unsigned int encrypted_datalen;
679 size_t master_keylen;
680 size_t asciilen;
681 int ret;
682
683 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
684 asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2;
685 if (strlen(hex_encoded_iv) != asciilen)
686 return -EINVAL;
687
688 hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2;
689 hex2bin(epayload->iv, hex_encoded_iv, ivsize);
690 hex2bin(epayload->encrypted_data, hex_encoded_data, encrypted_datalen);
691
692 hmac = epayload->format + epayload->datablob_len;
693 hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2), HASH_SIZE);
694
695 mkey = request_master_key(epayload, &master_key, &master_keylen);
696 if (IS_ERR(mkey))
697 return PTR_ERR(mkey);
698
699 ret = datablob_hmac_verify(epayload, format, master_key, master_keylen);
700 if (ret < 0) {
701 pr_err("encrypted_key: bad hmac (%d)\n", ret);
702 goto out;
703 }
704
705 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
706 if (ret < 0)
707 goto out;
708
709 ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key);
710 if (ret < 0)
711 pr_err("encrypted_key: failed to decrypt key (%d)\n", ret);
712out:
713 up_read(&mkey->sem);
714 key_put(mkey);
715 return ret;
716}
717
718static void __ekey_init(struct encrypted_key_payload *epayload,
719 const char *format, const char *master_desc,
720 const char *datalen)
721{
722 unsigned int format_len;
723
724 format_len = (!format) ? strlen(key_format_default) : strlen(format);
725 epayload->format = epayload->payload_data + epayload->payload_datalen;
726 epayload->master_desc = epayload->format + format_len + 1;
727 epayload->datalen = epayload->master_desc + strlen(master_desc) + 1;
728 epayload->iv = epayload->datalen + strlen(datalen) + 1;
729 epayload->encrypted_data = epayload->iv + ivsize + 1;
730 epayload->decrypted_data = epayload->payload_data;
731
732 if (!format)
733 memcpy(epayload->format, key_format_default, format_len);
734 else {
735 if (!strcmp(format, key_format_ecryptfs))
736 epayload->decrypted_data =
737 ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data);
738
739 memcpy(epayload->format, format, format_len);
740 }
741
742 memcpy(epayload->master_desc, master_desc, strlen(master_desc));
743 memcpy(epayload->datalen, datalen, strlen(datalen));
744}
745
746/*
747 * encrypted_init - initialize an encrypted key
748 *
749 * For a new key, use a random number for both the iv and data
750 * itself. For an old key, decrypt the hex encoded data.
751 */
752static int encrypted_init(struct encrypted_key_payload *epayload,
753 const char *key_desc, const char *format,
754 const char *master_desc, const char *datalen,
755 const char *hex_encoded_iv)
756{
757 int ret = 0;
758
759 if (format && !strcmp(format, key_format_ecryptfs)) {
760 ret = valid_ecryptfs_desc(key_desc);
761 if (ret < 0)
762 return ret;
763
764 ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data,
765 key_desc);
766 }
767
768 __ekey_init(epayload, format, master_desc, datalen);
769 if (!hex_encoded_iv) {
770 get_random_bytes(epayload->iv, ivsize);
771
772 get_random_bytes(epayload->decrypted_data,
773 epayload->decrypted_datalen);
774 } else
775 ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv);
776 return ret;
777}
778
779/*
780 * encrypted_instantiate - instantiate an encrypted key
781 *
782 * Decrypt an existing encrypted datablob or create a new encrypted key
783 * based on a kernel random number.
784 *
785 * On success, return 0. Otherwise return errno.
786 */
787static int encrypted_instantiate(struct key *key, const void *data,
788 size_t datalen)
789{
790 struct encrypted_key_payload *epayload = NULL;
791 char *datablob = NULL;
792 const char *format = NULL;
793 char *master_desc = NULL;
794 char *decrypted_datalen = NULL;
795 char *hex_encoded_iv = NULL;
796 int ret;
797
798 if (datalen <= 0 || datalen > 32767 || !data)
799 return -EINVAL;
800
801 datablob = kmalloc(datalen + 1, GFP_KERNEL);
802 if (!datablob)
803 return -ENOMEM;
804 datablob[datalen] = 0;
805 memcpy(datablob, data, datalen);
806 ret = datablob_parse(datablob, &format, &master_desc,
807 &decrypted_datalen, &hex_encoded_iv);
808 if (ret < 0)
809 goto out;
810
811 epayload = encrypted_key_alloc(key, format, master_desc,
812 decrypted_datalen);
813 if (IS_ERR(epayload)) {
814 ret = PTR_ERR(epayload);
815 goto out;
816 }
817 ret = encrypted_init(epayload, key->description, format, master_desc,
818 decrypted_datalen, hex_encoded_iv);
819 if (ret < 0) {
820 kfree(epayload);
821 goto out;
822 }
823
824 rcu_assign_pointer(key->payload.data, epayload);
825out:
826 kfree(datablob);
827 return ret;
828}
829
830static void encrypted_rcu_free(struct rcu_head *rcu)
831{
832 struct encrypted_key_payload *epayload;
833
834 epayload = container_of(rcu, struct encrypted_key_payload, rcu);
835 memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
836 kfree(epayload);
837}
838
839/*
840 * encrypted_update - update the master key description
841 *
842 * Change the master key description for an existing encrypted key.
843 * The next read will return an encrypted datablob using the new
844 * master key description.
845 *
846 * On success, return 0. Otherwise return errno.
847 */
848static int encrypted_update(struct key *key, const void *data, size_t datalen)
849{
850 struct encrypted_key_payload *epayload = key->payload.data;
851 struct encrypted_key_payload *new_epayload;
852 char *buf;
853 char *new_master_desc = NULL;
854 const char *format = NULL;
855 int ret = 0;
856
857 if (datalen <= 0 || datalen > 32767 || !data)
858 return -EINVAL;
859
860 buf = kmalloc(datalen + 1, GFP_KERNEL);
861 if (!buf)
862 return -ENOMEM;
863
864 buf[datalen] = 0;
865 memcpy(buf, data, datalen);
866 ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL);
867 if (ret < 0)
868 goto out;
869
870 ret = valid_master_desc(new_master_desc, epayload->master_desc);
871 if (ret < 0)
872 goto out;
873
874 new_epayload = encrypted_key_alloc(key, epayload->format,
875 new_master_desc, epayload->datalen);
876 if (IS_ERR(new_epayload)) {
877 ret = PTR_ERR(new_epayload);
878 goto out;
879 }
880
881 __ekey_init(new_epayload, epayload->format, new_master_desc,
882 epayload->datalen);
883
884 memcpy(new_epayload->iv, epayload->iv, ivsize);
885 memcpy(new_epayload->payload_data, epayload->payload_data,
886 epayload->payload_datalen);
887
888 rcu_assign_pointer(key->payload.data, new_epayload);
889 call_rcu(&epayload->rcu, encrypted_rcu_free);
890out:
891 kfree(buf);
892 return ret;
893}
894
895/*
896 * encrypted_read - format and copy the encrypted data to userspace
897 *
898 * The resulting datablob format is:
899 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data>
900 *
901 * On success, return to userspace the encrypted key datablob size.
902 */
903static long encrypted_read(const struct key *key, char __user *buffer,
904 size_t buflen)
905{
906 struct encrypted_key_payload *epayload;
907 struct key *mkey;
908 u8 *master_key;
909 size_t master_keylen;
910 char derived_key[HASH_SIZE];
911 char *ascii_buf;
912 size_t asciiblob_len;
913 int ret;
914
915 epayload = rcu_dereference_key(key);
916
917 /* returns the hex encoded iv, encrypted-data, and hmac as ascii */
918 asciiblob_len = epayload->datablob_len + ivsize + 1
919 + roundup(epayload->decrypted_datalen, blksize)
920 + (HASH_SIZE * 2);
921
922 if (!buffer || buflen < asciiblob_len)
923 return asciiblob_len;
924
925 mkey = request_master_key(epayload, &master_key, &master_keylen);
926 if (IS_ERR(mkey))
927 return PTR_ERR(mkey);
928
929 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
930 if (ret < 0)
931 goto out;
932
933 ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key);
934 if (ret < 0)
935 goto out;
936
937 ret = datablob_hmac_append(epayload, master_key, master_keylen);
938 if (ret < 0)
939 goto out;
940
941 ascii_buf = datablob_format(epayload, asciiblob_len);
942 if (!ascii_buf) {
943 ret = -ENOMEM;
944 goto out;
945 }
946
947 up_read(&mkey->sem);
948 key_put(mkey);
949
950 if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0)
951 ret = -EFAULT;
952 kfree(ascii_buf);
953
954 return asciiblob_len;
955out:
956 up_read(&mkey->sem);
957 key_put(mkey);
958 return ret;
959}
960
961/*
962 * encrypted_destroy - before freeing the key, clear the decrypted data
963 *
964 * Before freeing the key, clear the memory containing the decrypted
965 * key data.
966 */
967static void encrypted_destroy(struct key *key)
968{
969 struct encrypted_key_payload *epayload = key->payload.data;
970
971 if (!epayload)
972 return;
973
974 memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
975 kfree(key->payload.data);
976}
977
978struct key_type key_type_encrypted = {
979 .name = "encrypted",
980 .instantiate = encrypted_instantiate,
981 .update = encrypted_update,
982 .match = user_match,
983 .destroy = encrypted_destroy,
984 .describe = user_describe,
985 .read = encrypted_read,
986};
987EXPORT_SYMBOL_GPL(key_type_encrypted);
988
989static void encrypted_shash_release(void)
990{
991 if (hashalg)
992 crypto_free_shash(hashalg);
993 if (hmacalg)
994 crypto_free_shash(hmacalg);
995}
996
997static int __init encrypted_shash_alloc(void)
998{
999 int ret;
1000
1001 hmacalg = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC);
1002 if (IS_ERR(hmacalg)) {
1003 pr_info("encrypted_key: could not allocate crypto %s\n",
1004 hmac_alg);
1005 return PTR_ERR(hmacalg);
1006 }
1007
1008 hashalg = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC);
1009 if (IS_ERR(hashalg)) {
1010 pr_info("encrypted_key: could not allocate crypto %s\n",
1011 hash_alg);
1012 ret = PTR_ERR(hashalg);
1013 goto hashalg_fail;
1014 }
1015
1016 return 0;
1017
1018hashalg_fail:
1019 crypto_free_shash(hmacalg);
1020 return ret;
1021}
1022
1023static int __init init_encrypted(void)
1024{
1025 int ret;
1026
1027 ret = encrypted_shash_alloc();
1028 if (ret < 0)
1029 return ret;
1030 ret = register_key_type(&key_type_encrypted);
1031 if (ret < 0)
1032 goto out;
1033 return aes_get_sizes();
1034out:
1035 encrypted_shash_release();
1036 return ret;
1037
1038}
1039
1040static void __exit cleanup_encrypted(void)
1041{
1042 encrypted_shash_release();
1043 unregister_key_type(&key_type_encrypted);
1044}
1045
1046late_initcall(init_encrypted);
1047module_exit(cleanup_encrypted);
1048
1049MODULE_LICENSE("GPL");