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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 = hex_byte_pack(bufp, iv[i]);
297out:
298 return ascii_buf;
299}
300
301/*
302 * request_user_key - request the user key
303 *
304 * Use a user provided key to encrypt/decrypt an encrypted-key.
305 */
306static struct key *request_user_key(const char *master_desc, u8 **master_key,
307 size_t *master_keylen)
308{
309 struct user_key_payload *upayload;
310 struct key *ukey;
311
312 ukey = request_key(&key_type_user, master_desc, NULL);
313 if (IS_ERR(ukey))
314 goto error;
315
316 down_read(&ukey->sem);
317 upayload = ukey->payload.data;
318 *master_key = upayload->data;
319 *master_keylen = upayload->datalen;
320error:
321 return ukey;
322}
323
324static struct sdesc *alloc_sdesc(struct crypto_shash *alg)
325{
326 struct sdesc *sdesc;
327 int size;
328
329 size = sizeof(struct shash_desc) + crypto_shash_descsize(alg);
330 sdesc = kmalloc(size, GFP_KERNEL);
331 if (!sdesc)
332 return ERR_PTR(-ENOMEM);
333 sdesc->shash.tfm = alg;
334 sdesc->shash.flags = 0x0;
335 return sdesc;
336}
337
338static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen,
339 const u8 *buf, unsigned int buflen)
340{
341 struct sdesc *sdesc;
342 int ret;
343
344 sdesc = alloc_sdesc(hmacalg);
345 if (IS_ERR(sdesc)) {
346 pr_info("encrypted_key: can't alloc %s\n", hmac_alg);
347 return PTR_ERR(sdesc);
348 }
349
350 ret = crypto_shash_setkey(hmacalg, key, keylen);
351 if (!ret)
352 ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
353 kfree(sdesc);
354 return ret;
355}
356
357static int calc_hash(u8 *digest, const u8 *buf, unsigned int buflen)
358{
359 struct sdesc *sdesc;
360 int ret;
361
362 sdesc = alloc_sdesc(hashalg);
363 if (IS_ERR(sdesc)) {
364 pr_info("encrypted_key: can't alloc %s\n", hash_alg);
365 return PTR_ERR(sdesc);
366 }
367
368 ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
369 kfree(sdesc);
370 return ret;
371}
372
373enum derived_key_type { ENC_KEY, AUTH_KEY };
374
375/* Derive authentication/encryption key from trusted key */
376static int get_derived_key(u8 *derived_key, enum derived_key_type key_type,
377 const u8 *master_key, size_t master_keylen)
378{
379 u8 *derived_buf;
380 unsigned int derived_buf_len;
381 int ret;
382
383 derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen;
384 if (derived_buf_len < HASH_SIZE)
385 derived_buf_len = HASH_SIZE;
386
387 derived_buf = kzalloc(derived_buf_len, GFP_KERNEL);
388 if (!derived_buf) {
389 pr_err("encrypted_key: out of memory\n");
390 return -ENOMEM;
391 }
392 if (key_type)
393 strcpy(derived_buf, "AUTH_KEY");
394 else
395 strcpy(derived_buf, "ENC_KEY");
396
397 memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
398 master_keylen);
399 ret = calc_hash(derived_key, derived_buf, derived_buf_len);
400 kfree(derived_buf);
401 return ret;
402}
403
404static int init_blkcipher_desc(struct blkcipher_desc *desc, const u8 *key,
405 unsigned int key_len, const u8 *iv,
406 unsigned int ivsize)
407{
408 int ret;
409
410 desc->tfm = crypto_alloc_blkcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
411 if (IS_ERR(desc->tfm)) {
412 pr_err("encrypted_key: failed to load %s transform (%ld)\n",
413 blkcipher_alg, PTR_ERR(desc->tfm));
414 return PTR_ERR(desc->tfm);
415 }
416 desc->flags = 0;
417
418 ret = crypto_blkcipher_setkey(desc->tfm, key, key_len);
419 if (ret < 0) {
420 pr_err("encrypted_key: failed to setkey (%d)\n", ret);
421 crypto_free_blkcipher(desc->tfm);
422 return ret;
423 }
424 crypto_blkcipher_set_iv(desc->tfm, iv, ivsize);
425 return 0;
426}
427
428static struct key *request_master_key(struct encrypted_key_payload *epayload,
429 u8 **master_key, size_t *master_keylen)
430{
431 struct key *mkey = NULL;
432
433 if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX,
434 KEY_TRUSTED_PREFIX_LEN)) {
435 mkey = request_trusted_key(epayload->master_desc +
436 KEY_TRUSTED_PREFIX_LEN,
437 master_key, master_keylen);
438 } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX,
439 KEY_USER_PREFIX_LEN)) {
440 mkey = request_user_key(epayload->master_desc +
441 KEY_USER_PREFIX_LEN,
442 master_key, master_keylen);
443 } else
444 goto out;
445
446 if (IS_ERR(mkey)) {
447 int ret = PTR_ERR(mkey);
448
449 if (ret == -ENOTSUPP)
450 pr_info("encrypted_key: key %s not supported",
451 epayload->master_desc);
452 else
453 pr_info("encrypted_key: key %s not found",
454 epayload->master_desc);
455 goto out;
456 }
457
458 dump_master_key(*master_key, *master_keylen);
459out:
460 return mkey;
461}
462
463/* Before returning data to userspace, encrypt decrypted data. */
464static int derived_key_encrypt(struct encrypted_key_payload *epayload,
465 const u8 *derived_key,
466 unsigned int derived_keylen)
467{
468 struct scatterlist sg_in[2];
469 struct scatterlist sg_out[1];
470 struct blkcipher_desc desc;
471 unsigned int encrypted_datalen;
472 unsigned int padlen;
473 char pad[16];
474 int ret;
475
476 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
477 padlen = encrypted_datalen - epayload->decrypted_datalen;
478
479 ret = init_blkcipher_desc(&desc, derived_key, derived_keylen,
480 epayload->iv, ivsize);
481 if (ret < 0)
482 goto out;
483 dump_decrypted_data(epayload);
484
485 memset(pad, 0, sizeof pad);
486 sg_init_table(sg_in, 2);
487 sg_set_buf(&sg_in[0], epayload->decrypted_data,
488 epayload->decrypted_datalen);
489 sg_set_buf(&sg_in[1], pad, padlen);
490
491 sg_init_table(sg_out, 1);
492 sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
493
494 ret = crypto_blkcipher_encrypt(&desc, sg_out, sg_in, encrypted_datalen);
495 crypto_free_blkcipher(desc.tfm);
496 if (ret < 0)
497 pr_err("encrypted_key: failed to encrypt (%d)\n", ret);
498 else
499 dump_encrypted_data(epayload, encrypted_datalen);
500out:
501 return ret;
502}
503
504static int datablob_hmac_append(struct encrypted_key_payload *epayload,
505 const u8 *master_key, size_t master_keylen)
506{
507 u8 derived_key[HASH_SIZE];
508 u8 *digest;
509 int ret;
510
511 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
512 if (ret < 0)
513 goto out;
514
515 digest = epayload->format + epayload->datablob_len;
516 ret = calc_hmac(digest, derived_key, sizeof derived_key,
517 epayload->format, epayload->datablob_len);
518 if (!ret)
519 dump_hmac(NULL, digest, HASH_SIZE);
520out:
521 return ret;
522}
523
524/* verify HMAC before decrypting encrypted key */
525static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
526 const u8 *format, const u8 *master_key,
527 size_t master_keylen)
528{
529 u8 derived_key[HASH_SIZE];
530 u8 digest[HASH_SIZE];
531 int ret;
532 char *p;
533 unsigned short len;
534
535 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
536 if (ret < 0)
537 goto out;
538
539 len = epayload->datablob_len;
540 if (!format) {
541 p = epayload->master_desc;
542 len -= strlen(epayload->format) + 1;
543 } else
544 p = epayload->format;
545
546 ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len);
547 if (ret < 0)
548 goto out;
549 ret = memcmp(digest, epayload->format + epayload->datablob_len,
550 sizeof digest);
551 if (ret) {
552 ret = -EINVAL;
553 dump_hmac("datablob",
554 epayload->format + epayload->datablob_len,
555 HASH_SIZE);
556 dump_hmac("calc", digest, HASH_SIZE);
557 }
558out:
559 return ret;
560}
561
562static int derived_key_decrypt(struct encrypted_key_payload *epayload,
563 const u8 *derived_key,
564 unsigned int derived_keylen)
565{
566 struct scatterlist sg_in[1];
567 struct scatterlist sg_out[2];
568 struct blkcipher_desc desc;
569 unsigned int encrypted_datalen;
570 char pad[16];
571 int ret;
572
573 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
574 ret = init_blkcipher_desc(&desc, derived_key, derived_keylen,
575 epayload->iv, ivsize);
576 if (ret < 0)
577 goto out;
578 dump_encrypted_data(epayload, encrypted_datalen);
579
580 memset(pad, 0, sizeof pad);
581 sg_init_table(sg_in, 1);
582 sg_init_table(sg_out, 2);
583 sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen);
584 sg_set_buf(&sg_out[0], epayload->decrypted_data,
585 epayload->decrypted_datalen);
586 sg_set_buf(&sg_out[1], pad, sizeof pad);
587
588 ret = crypto_blkcipher_decrypt(&desc, sg_out, sg_in, encrypted_datalen);
589 crypto_free_blkcipher(desc.tfm);
590 if (ret < 0)
591 goto out;
592 dump_decrypted_data(epayload);
593out:
594 return ret;
595}
596
597/* Allocate memory for decrypted key and datablob. */
598static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
599 const char *format,
600 const char *master_desc,
601 const char *datalen)
602{
603 struct encrypted_key_payload *epayload = NULL;
604 unsigned short datablob_len;
605 unsigned short decrypted_datalen;
606 unsigned short payload_datalen;
607 unsigned int encrypted_datalen;
608 unsigned int format_len;
609 long dlen;
610 int ret;
611
612 ret = kstrtol(datalen, 10, &dlen);
613 if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE)
614 return ERR_PTR(-EINVAL);
615
616 format_len = (!format) ? strlen(key_format_default) : strlen(format);
617 decrypted_datalen = dlen;
618 payload_datalen = decrypted_datalen;
619 if (format && !strcmp(format, key_format_ecryptfs)) {
620 if (dlen != ECRYPTFS_MAX_KEY_BYTES) {
621 pr_err("encrypted_key: keylen for the ecryptfs format "
622 "must be equal to %d bytes\n",
623 ECRYPTFS_MAX_KEY_BYTES);
624 return ERR_PTR(-EINVAL);
625 }
626 decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES;
627 payload_datalen = sizeof(struct ecryptfs_auth_tok);
628 }
629
630 encrypted_datalen = roundup(decrypted_datalen, blksize);
631
632 datablob_len = format_len + 1 + strlen(master_desc) + 1
633 + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen;
634
635 ret = key_payload_reserve(key, payload_datalen + datablob_len
636 + HASH_SIZE + 1);
637 if (ret < 0)
638 return ERR_PTR(ret);
639
640 epayload = kzalloc(sizeof(*epayload) + payload_datalen +
641 datablob_len + HASH_SIZE + 1, GFP_KERNEL);
642 if (!epayload)
643 return ERR_PTR(-ENOMEM);
644
645 epayload->payload_datalen = payload_datalen;
646 epayload->decrypted_datalen = decrypted_datalen;
647 epayload->datablob_len = datablob_len;
648 return epayload;
649}
650
651static int encrypted_key_decrypt(struct encrypted_key_payload *epayload,
652 const char *format, const char *hex_encoded_iv)
653{
654 struct key *mkey;
655 u8 derived_key[HASH_SIZE];
656 u8 *master_key;
657 u8 *hmac;
658 const char *hex_encoded_data;
659 unsigned int encrypted_datalen;
660 size_t master_keylen;
661 size_t asciilen;
662 int ret;
663
664 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
665 asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2;
666 if (strlen(hex_encoded_iv) != asciilen)
667 return -EINVAL;
668
669 hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2;
670 ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize);
671 if (ret < 0)
672 return -EINVAL;
673 ret = hex2bin(epayload->encrypted_data, hex_encoded_data,
674 encrypted_datalen);
675 if (ret < 0)
676 return -EINVAL;
677
678 hmac = epayload->format + epayload->datablob_len;
679 ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2),
680 HASH_SIZE);
681 if (ret < 0)
682 return -EINVAL;
683
684 mkey = request_master_key(epayload, &master_key, &master_keylen);
685 if (IS_ERR(mkey))
686 return PTR_ERR(mkey);
687
688 ret = datablob_hmac_verify(epayload, format, master_key, master_keylen);
689 if (ret < 0) {
690 pr_err("encrypted_key: bad hmac (%d)\n", ret);
691 goto out;
692 }
693
694 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
695 if (ret < 0)
696 goto out;
697
698 ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key);
699 if (ret < 0)
700 pr_err("encrypted_key: failed to decrypt key (%d)\n", ret);
701out:
702 up_read(&mkey->sem);
703 key_put(mkey);
704 return ret;
705}
706
707static void __ekey_init(struct encrypted_key_payload *epayload,
708 const char *format, const char *master_desc,
709 const char *datalen)
710{
711 unsigned int format_len;
712
713 format_len = (!format) ? strlen(key_format_default) : strlen(format);
714 epayload->format = epayload->payload_data + epayload->payload_datalen;
715 epayload->master_desc = epayload->format + format_len + 1;
716 epayload->datalen = epayload->master_desc + strlen(master_desc) + 1;
717 epayload->iv = epayload->datalen + strlen(datalen) + 1;
718 epayload->encrypted_data = epayload->iv + ivsize + 1;
719 epayload->decrypted_data = epayload->payload_data;
720
721 if (!format)
722 memcpy(epayload->format, key_format_default, format_len);
723 else {
724 if (!strcmp(format, key_format_ecryptfs))
725 epayload->decrypted_data =
726 ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data);
727
728 memcpy(epayload->format, format, format_len);
729 }
730
731 memcpy(epayload->master_desc, master_desc, strlen(master_desc));
732 memcpy(epayload->datalen, datalen, strlen(datalen));
733}
734
735/*
736 * encrypted_init - initialize an encrypted key
737 *
738 * For a new key, use a random number for both the iv and data
739 * itself. For an old key, decrypt the hex encoded data.
740 */
741static int encrypted_init(struct encrypted_key_payload *epayload,
742 const char *key_desc, const char *format,
743 const char *master_desc, const char *datalen,
744 const char *hex_encoded_iv)
745{
746 int ret = 0;
747
748 if (format && !strcmp(format, key_format_ecryptfs)) {
749 ret = valid_ecryptfs_desc(key_desc);
750 if (ret < 0)
751 return ret;
752
753 ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data,
754 key_desc);
755 }
756
757 __ekey_init(epayload, format, master_desc, datalen);
758 if (!hex_encoded_iv) {
759 get_random_bytes(epayload->iv, ivsize);
760
761 get_random_bytes(epayload->decrypted_data,
762 epayload->decrypted_datalen);
763 } else
764 ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv);
765 return ret;
766}
767
768/*
769 * encrypted_instantiate - instantiate an encrypted key
770 *
771 * Decrypt an existing encrypted datablob or create a new encrypted key
772 * based on a kernel random number.
773 *
774 * On success, return 0. Otherwise return errno.
775 */
776static int encrypted_instantiate(struct key *key,
777 struct key_preparsed_payload *prep)
778{
779 struct encrypted_key_payload *epayload = NULL;
780 char *datablob = NULL;
781 const char *format = NULL;
782 char *master_desc = NULL;
783 char *decrypted_datalen = NULL;
784 char *hex_encoded_iv = NULL;
785 size_t datalen = prep->datalen;
786 int ret;
787
788 if (datalen <= 0 || datalen > 32767 || !prep->data)
789 return -EINVAL;
790
791 datablob = kmalloc(datalen + 1, GFP_KERNEL);
792 if (!datablob)
793 return -ENOMEM;
794 datablob[datalen] = 0;
795 memcpy(datablob, prep->data, datalen);
796 ret = datablob_parse(datablob, &format, &master_desc,
797 &decrypted_datalen, &hex_encoded_iv);
798 if (ret < 0)
799 goto out;
800
801 epayload = encrypted_key_alloc(key, format, master_desc,
802 decrypted_datalen);
803 if (IS_ERR(epayload)) {
804 ret = PTR_ERR(epayload);
805 goto out;
806 }
807 ret = encrypted_init(epayload, key->description, format, master_desc,
808 decrypted_datalen, hex_encoded_iv);
809 if (ret < 0) {
810 kfree(epayload);
811 goto out;
812 }
813
814 rcu_assign_keypointer(key, epayload);
815out:
816 kfree(datablob);
817 return ret;
818}
819
820static void encrypted_rcu_free(struct rcu_head *rcu)
821{
822 struct encrypted_key_payload *epayload;
823
824 epayload = container_of(rcu, struct encrypted_key_payload, rcu);
825 memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
826 kfree(epayload);
827}
828
829/*
830 * encrypted_update - update the master key description
831 *
832 * Change the master key description for an existing encrypted key.
833 * The next read will return an encrypted datablob using the new
834 * master key description.
835 *
836 * On success, return 0. Otherwise return errno.
837 */
838static int encrypted_update(struct key *key, struct key_preparsed_payload *prep)
839{
840 struct encrypted_key_payload *epayload = key->payload.data;
841 struct encrypted_key_payload *new_epayload;
842 char *buf;
843 char *new_master_desc = NULL;
844 const char *format = NULL;
845 size_t datalen = prep->datalen;
846 int ret = 0;
847
848 if (datalen <= 0 || datalen > 32767 || !prep->data)
849 return -EINVAL;
850
851 buf = kmalloc(datalen + 1, GFP_KERNEL);
852 if (!buf)
853 return -ENOMEM;
854
855 buf[datalen] = 0;
856 memcpy(buf, prep->data, datalen);
857 ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL);
858 if (ret < 0)
859 goto out;
860
861 ret = valid_master_desc(new_master_desc, epayload->master_desc);
862 if (ret < 0)
863 goto out;
864
865 new_epayload = encrypted_key_alloc(key, epayload->format,
866 new_master_desc, epayload->datalen);
867 if (IS_ERR(new_epayload)) {
868 ret = PTR_ERR(new_epayload);
869 goto out;
870 }
871
872 __ekey_init(new_epayload, epayload->format, new_master_desc,
873 epayload->datalen);
874
875 memcpy(new_epayload->iv, epayload->iv, ivsize);
876 memcpy(new_epayload->payload_data, epayload->payload_data,
877 epayload->payload_datalen);
878
879 rcu_assign_keypointer(key, new_epayload);
880 call_rcu(&epayload->rcu, encrypted_rcu_free);
881out:
882 kfree(buf);
883 return ret;
884}
885
886/*
887 * encrypted_read - format and copy the encrypted data to userspace
888 *
889 * The resulting datablob format is:
890 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data>
891 *
892 * On success, return to userspace the encrypted key datablob size.
893 */
894static long encrypted_read(const struct key *key, char __user *buffer,
895 size_t buflen)
896{
897 struct encrypted_key_payload *epayload;
898 struct key *mkey;
899 u8 *master_key;
900 size_t master_keylen;
901 char derived_key[HASH_SIZE];
902 char *ascii_buf;
903 size_t asciiblob_len;
904 int ret;
905
906 epayload = rcu_dereference_key(key);
907
908 /* returns the hex encoded iv, encrypted-data, and hmac as ascii */
909 asciiblob_len = epayload->datablob_len + ivsize + 1
910 + roundup(epayload->decrypted_datalen, blksize)
911 + (HASH_SIZE * 2);
912
913 if (!buffer || buflen < asciiblob_len)
914 return asciiblob_len;
915
916 mkey = request_master_key(epayload, &master_key, &master_keylen);
917 if (IS_ERR(mkey))
918 return PTR_ERR(mkey);
919
920 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
921 if (ret < 0)
922 goto out;
923
924 ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key);
925 if (ret < 0)
926 goto out;
927
928 ret = datablob_hmac_append(epayload, master_key, master_keylen);
929 if (ret < 0)
930 goto out;
931
932 ascii_buf = datablob_format(epayload, asciiblob_len);
933 if (!ascii_buf) {
934 ret = -ENOMEM;
935 goto out;
936 }
937
938 up_read(&mkey->sem);
939 key_put(mkey);
940
941 if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0)
942 ret = -EFAULT;
943 kfree(ascii_buf);
944
945 return asciiblob_len;
946out:
947 up_read(&mkey->sem);
948 key_put(mkey);
949 return ret;
950}
951
952/*
953 * encrypted_destroy - before freeing the key, clear the decrypted data
954 *
955 * Before freeing the key, clear the memory containing the decrypted
956 * key data.
957 */
958static void encrypted_destroy(struct key *key)
959{
960 struct encrypted_key_payload *epayload = key->payload.data;
961
962 if (!epayload)
963 return;
964
965 memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
966 kfree(key->payload.data);
967}
968
969struct key_type key_type_encrypted = {
970 .name = "encrypted",
971 .instantiate = encrypted_instantiate,
972 .update = encrypted_update,
973 .match = user_match,
974 .destroy = encrypted_destroy,
975 .describe = user_describe,
976 .read = encrypted_read,
977};
978EXPORT_SYMBOL_GPL(key_type_encrypted);
979
980static void encrypted_shash_release(void)
981{
982 if (hashalg)
983 crypto_free_shash(hashalg);
984 if (hmacalg)
985 crypto_free_shash(hmacalg);
986}
987
988static int __init encrypted_shash_alloc(void)
989{
990 int ret;
991
992 hmacalg = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC);
993 if (IS_ERR(hmacalg)) {
994 pr_info("encrypted_key: could not allocate crypto %s\n",
995 hmac_alg);
996 return PTR_ERR(hmacalg);
997 }
998
999 hashalg = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC);
1000 if (IS_ERR(hashalg)) {
1001 pr_info("encrypted_key: could not allocate crypto %s\n",
1002 hash_alg);
1003 ret = PTR_ERR(hashalg);
1004 goto hashalg_fail;
1005 }
1006
1007 return 0;
1008
1009hashalg_fail:
1010 crypto_free_shash(hmacalg);
1011 return ret;
1012}
1013
1014static int __init init_encrypted(void)
1015{
1016 int ret;
1017
1018 ret = encrypted_shash_alloc();
1019 if (ret < 0)
1020 return ret;
1021 ret = register_key_type(&key_type_encrypted);
1022 if (ret < 0)
1023 goto out;
1024 return aes_get_sizes();
1025out:
1026 encrypted_shash_release();
1027 return ret;
1028
1029}
1030
1031static void __exit cleanup_encrypted(void)
1032{
1033 encrypted_shash_release();
1034 unregister_key_type(&key_type_encrypted);
1035}
1036
1037late_initcall(init_encrypted);
1038module_exit(cleanup_encrypted);
1039
1040MODULE_LICENSE("GPL");
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/ctype.h>
32#include <crypto/hash.h>
33#include <crypto/sha.h>
34#include <crypto/skcipher.h>
35
36#include "encrypted.h"
37#include "ecryptfs_format.h"
38
39static const char KEY_TRUSTED_PREFIX[] = "trusted:";
40static const char KEY_USER_PREFIX[] = "user:";
41static const char hash_alg[] = "sha256";
42static const char hmac_alg[] = "hmac(sha256)";
43static const char blkcipher_alg[] = "cbc(aes)";
44static const char key_format_default[] = "default";
45static const char key_format_ecryptfs[] = "ecryptfs";
46static unsigned int ivsize;
47static int blksize;
48
49#define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1)
50#define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1)
51#define KEY_ECRYPTFS_DESC_LEN 16
52#define HASH_SIZE SHA256_DIGEST_SIZE
53#define MAX_DATA_SIZE 4096
54#define MIN_DATA_SIZE 20
55
56struct sdesc {
57 struct shash_desc shash;
58 char ctx[];
59};
60
61static struct crypto_shash *hashalg;
62static struct crypto_shash *hmacalg;
63
64enum {
65 Opt_err = -1, Opt_new, Opt_load, Opt_update
66};
67
68enum {
69 Opt_error = -1, Opt_default, Opt_ecryptfs
70};
71
72static const match_table_t key_format_tokens = {
73 {Opt_default, "default"},
74 {Opt_ecryptfs, "ecryptfs"},
75 {Opt_error, NULL}
76};
77
78static const match_table_t key_tokens = {
79 {Opt_new, "new"},
80 {Opt_load, "load"},
81 {Opt_update, "update"},
82 {Opt_err, NULL}
83};
84
85static int aes_get_sizes(void)
86{
87 struct crypto_skcipher *tfm;
88
89 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
90 if (IS_ERR(tfm)) {
91 pr_err("encrypted_key: failed to alloc_cipher (%ld)\n",
92 PTR_ERR(tfm));
93 return PTR_ERR(tfm);
94 }
95 ivsize = crypto_skcipher_ivsize(tfm);
96 blksize = crypto_skcipher_blocksize(tfm);
97 crypto_free_skcipher(tfm);
98 return 0;
99}
100
101/*
102 * valid_ecryptfs_desc - verify the description of a new/loaded encrypted key
103 *
104 * The description of a encrypted key with format 'ecryptfs' must contain
105 * exactly 16 hexadecimal characters.
106 *
107 */
108static int valid_ecryptfs_desc(const char *ecryptfs_desc)
109{
110 int i;
111
112 if (strlen(ecryptfs_desc) != KEY_ECRYPTFS_DESC_LEN) {
113 pr_err("encrypted_key: key description must be %d hexadecimal "
114 "characters long\n", KEY_ECRYPTFS_DESC_LEN);
115 return -EINVAL;
116 }
117
118 for (i = 0; i < KEY_ECRYPTFS_DESC_LEN; i++) {
119 if (!isxdigit(ecryptfs_desc[i])) {
120 pr_err("encrypted_key: key description must contain "
121 "only hexadecimal characters\n");
122 return -EINVAL;
123 }
124 }
125
126 return 0;
127}
128
129/*
130 * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key
131 *
132 * key-type:= "trusted:" | "user:"
133 * desc:= master-key description
134 *
135 * Verify that 'key-type' is valid and that 'desc' exists. On key update,
136 * only the master key description is permitted to change, not the key-type.
137 * The key-type remains constant.
138 *
139 * On success returns 0, otherwise -EINVAL.
140 */
141static int valid_master_desc(const char *new_desc, const char *orig_desc)
142{
143 if (!memcmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) {
144 if (strlen(new_desc) == KEY_TRUSTED_PREFIX_LEN)
145 goto out;
146 if (orig_desc)
147 if (memcmp(new_desc, orig_desc, KEY_TRUSTED_PREFIX_LEN))
148 goto out;
149 } else if (!memcmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) {
150 if (strlen(new_desc) == KEY_USER_PREFIX_LEN)
151 goto out;
152 if (orig_desc)
153 if (memcmp(new_desc, orig_desc, KEY_USER_PREFIX_LEN))
154 goto out;
155 } else
156 goto out;
157 return 0;
158out:
159 return -EINVAL;
160}
161
162/*
163 * datablob_parse - parse the keyctl data
164 *
165 * datablob format:
166 * new [<format>] <master-key name> <decrypted data length>
167 * load [<format>] <master-key name> <decrypted data length>
168 * <encrypted iv + data>
169 * update <new-master-key name>
170 *
171 * Tokenizes a copy of the keyctl data, returning a pointer to each token,
172 * which is null terminated.
173 *
174 * On success returns 0, otherwise -EINVAL.
175 */
176static int datablob_parse(char *datablob, const char **format,
177 char **master_desc, char **decrypted_datalen,
178 char **hex_encoded_iv)
179{
180 substring_t args[MAX_OPT_ARGS];
181 int ret = -EINVAL;
182 int key_cmd;
183 int key_format;
184 char *p, *keyword;
185
186 keyword = strsep(&datablob, " \t");
187 if (!keyword) {
188 pr_info("encrypted_key: insufficient parameters specified\n");
189 return ret;
190 }
191 key_cmd = match_token(keyword, key_tokens, args);
192
193 /* Get optional format: default | ecryptfs */
194 p = strsep(&datablob, " \t");
195 if (!p) {
196 pr_err("encrypted_key: insufficient parameters specified\n");
197 return ret;
198 }
199
200 key_format = match_token(p, key_format_tokens, args);
201 switch (key_format) {
202 case Opt_ecryptfs:
203 case Opt_default:
204 *format = p;
205 *master_desc = strsep(&datablob, " \t");
206 break;
207 case Opt_error:
208 *master_desc = p;
209 break;
210 }
211
212 if (!*master_desc) {
213 pr_info("encrypted_key: master key parameter is missing\n");
214 goto out;
215 }
216
217 if (valid_master_desc(*master_desc, NULL) < 0) {
218 pr_info("encrypted_key: master key parameter \'%s\' "
219 "is invalid\n", *master_desc);
220 goto out;
221 }
222
223 if (decrypted_datalen) {
224 *decrypted_datalen = strsep(&datablob, " \t");
225 if (!*decrypted_datalen) {
226 pr_info("encrypted_key: keylen parameter is missing\n");
227 goto out;
228 }
229 }
230
231 switch (key_cmd) {
232 case Opt_new:
233 if (!decrypted_datalen) {
234 pr_info("encrypted_key: keyword \'%s\' not allowed "
235 "when called from .update method\n", keyword);
236 break;
237 }
238 ret = 0;
239 break;
240 case Opt_load:
241 if (!decrypted_datalen) {
242 pr_info("encrypted_key: keyword \'%s\' not allowed "
243 "when called from .update method\n", keyword);
244 break;
245 }
246 *hex_encoded_iv = strsep(&datablob, " \t");
247 if (!*hex_encoded_iv) {
248 pr_info("encrypted_key: hex blob is missing\n");
249 break;
250 }
251 ret = 0;
252 break;
253 case Opt_update:
254 if (decrypted_datalen) {
255 pr_info("encrypted_key: keyword \'%s\' not allowed "
256 "when called from .instantiate method\n",
257 keyword);
258 break;
259 }
260 ret = 0;
261 break;
262 case Opt_err:
263 pr_info("encrypted_key: keyword \'%s\' not recognized\n",
264 keyword);
265 break;
266 }
267out:
268 return ret;
269}
270
271/*
272 * datablob_format - format as an ascii string, before copying to userspace
273 */
274static char *datablob_format(struct encrypted_key_payload *epayload,
275 size_t asciiblob_len)
276{
277 char *ascii_buf, *bufp;
278 u8 *iv = epayload->iv;
279 int len;
280 int i;
281
282 ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL);
283 if (!ascii_buf)
284 goto out;
285
286 ascii_buf[asciiblob_len] = '\0';
287
288 /* copy datablob master_desc and datalen strings */
289 len = sprintf(ascii_buf, "%s %s %s ", epayload->format,
290 epayload->master_desc, epayload->datalen);
291
292 /* convert the hex encoded iv, encrypted-data and HMAC to ascii */
293 bufp = &ascii_buf[len];
294 for (i = 0; i < (asciiblob_len - len) / 2; i++)
295 bufp = hex_byte_pack(bufp, iv[i]);
296out:
297 return ascii_buf;
298}
299
300/*
301 * request_user_key - request the user key
302 *
303 * Use a user provided key to encrypt/decrypt an encrypted-key.
304 */
305static struct key *request_user_key(const char *master_desc, const u8 **master_key,
306 size_t *master_keylen)
307{
308 const struct user_key_payload *upayload;
309 struct key *ukey;
310
311 ukey = request_key(&key_type_user, master_desc, NULL);
312 if (IS_ERR(ukey))
313 goto error;
314
315 down_read(&ukey->sem);
316 upayload = user_key_payload(ukey);
317 *master_key = upayload->data;
318 *master_keylen = upayload->datalen;
319error:
320 return ukey;
321}
322
323static struct sdesc *alloc_sdesc(struct crypto_shash *alg)
324{
325 struct sdesc *sdesc;
326 int size;
327
328 size = sizeof(struct shash_desc) + crypto_shash_descsize(alg);
329 sdesc = kmalloc(size, GFP_KERNEL);
330 if (!sdesc)
331 return ERR_PTR(-ENOMEM);
332 sdesc->shash.tfm = alg;
333 sdesc->shash.flags = 0x0;
334 return sdesc;
335}
336
337static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen,
338 const u8 *buf, unsigned int buflen)
339{
340 struct sdesc *sdesc;
341 int ret;
342
343 sdesc = alloc_sdesc(hmacalg);
344 if (IS_ERR(sdesc)) {
345 pr_info("encrypted_key: can't alloc %s\n", hmac_alg);
346 return PTR_ERR(sdesc);
347 }
348
349 ret = crypto_shash_setkey(hmacalg, key, keylen);
350 if (!ret)
351 ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
352 kfree(sdesc);
353 return ret;
354}
355
356static int calc_hash(u8 *digest, const u8 *buf, unsigned int buflen)
357{
358 struct sdesc *sdesc;
359 int ret;
360
361 sdesc = alloc_sdesc(hashalg);
362 if (IS_ERR(sdesc)) {
363 pr_info("encrypted_key: can't alloc %s\n", hash_alg);
364 return PTR_ERR(sdesc);
365 }
366
367 ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
368 kfree(sdesc);
369 return ret;
370}
371
372enum derived_key_type { ENC_KEY, AUTH_KEY };
373
374/* Derive authentication/encryption key from trusted key */
375static int get_derived_key(u8 *derived_key, enum derived_key_type key_type,
376 const u8 *master_key, size_t master_keylen)
377{
378 u8 *derived_buf;
379 unsigned int derived_buf_len;
380 int ret;
381
382 derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen;
383 if (derived_buf_len < HASH_SIZE)
384 derived_buf_len = HASH_SIZE;
385
386 derived_buf = kzalloc(derived_buf_len, GFP_KERNEL);
387 if (!derived_buf) {
388 pr_err("encrypted_key: out of memory\n");
389 return -ENOMEM;
390 }
391 if (key_type)
392 strcpy(derived_buf, "AUTH_KEY");
393 else
394 strcpy(derived_buf, "ENC_KEY");
395
396 memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
397 master_keylen);
398 ret = calc_hash(derived_key, derived_buf, derived_buf_len);
399 kfree(derived_buf);
400 return ret;
401}
402
403static struct skcipher_request *init_skcipher_req(const u8 *key,
404 unsigned int key_len)
405{
406 struct skcipher_request *req;
407 struct crypto_skcipher *tfm;
408 int ret;
409
410 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
411 if (IS_ERR(tfm)) {
412 pr_err("encrypted_key: failed to load %s transform (%ld)\n",
413 blkcipher_alg, PTR_ERR(tfm));
414 return ERR_CAST(tfm);
415 }
416
417 ret = crypto_skcipher_setkey(tfm, key, key_len);
418 if (ret < 0) {
419 pr_err("encrypted_key: failed to setkey (%d)\n", ret);
420 crypto_free_skcipher(tfm);
421 return ERR_PTR(ret);
422 }
423
424 req = skcipher_request_alloc(tfm, GFP_KERNEL);
425 if (!req) {
426 pr_err("encrypted_key: failed to allocate request for %s\n",
427 blkcipher_alg);
428 crypto_free_skcipher(tfm);
429 return ERR_PTR(-ENOMEM);
430 }
431
432 skcipher_request_set_callback(req, 0, NULL, NULL);
433 return req;
434}
435
436static struct key *request_master_key(struct encrypted_key_payload *epayload,
437 const u8 **master_key, size_t *master_keylen)
438{
439 struct key *mkey = NULL;
440
441 if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX,
442 KEY_TRUSTED_PREFIX_LEN)) {
443 mkey = request_trusted_key(epayload->master_desc +
444 KEY_TRUSTED_PREFIX_LEN,
445 master_key, master_keylen);
446 } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX,
447 KEY_USER_PREFIX_LEN)) {
448 mkey = request_user_key(epayload->master_desc +
449 KEY_USER_PREFIX_LEN,
450 master_key, master_keylen);
451 } else
452 goto out;
453
454 if (IS_ERR(mkey)) {
455 int ret = PTR_ERR(mkey);
456
457 if (ret == -ENOTSUPP)
458 pr_info("encrypted_key: key %s not supported",
459 epayload->master_desc);
460 else
461 pr_info("encrypted_key: key %s not found",
462 epayload->master_desc);
463 goto out;
464 }
465
466 dump_master_key(*master_key, *master_keylen);
467out:
468 return mkey;
469}
470
471/* Before returning data to userspace, encrypt decrypted data. */
472static int derived_key_encrypt(struct encrypted_key_payload *epayload,
473 const u8 *derived_key,
474 unsigned int derived_keylen)
475{
476 struct scatterlist sg_in[2];
477 struct scatterlist sg_out[1];
478 struct crypto_skcipher *tfm;
479 struct skcipher_request *req;
480 unsigned int encrypted_datalen;
481 unsigned int padlen;
482 char pad[16];
483 int ret;
484
485 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
486 padlen = encrypted_datalen - epayload->decrypted_datalen;
487
488 req = init_skcipher_req(derived_key, derived_keylen);
489 ret = PTR_ERR(req);
490 if (IS_ERR(req))
491 goto out;
492 dump_decrypted_data(epayload);
493
494 memset(pad, 0, sizeof pad);
495 sg_init_table(sg_in, 2);
496 sg_set_buf(&sg_in[0], epayload->decrypted_data,
497 epayload->decrypted_datalen);
498 sg_set_buf(&sg_in[1], pad, padlen);
499
500 sg_init_table(sg_out, 1);
501 sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
502
503 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen,
504 epayload->iv);
505 ret = crypto_skcipher_encrypt(req);
506 tfm = crypto_skcipher_reqtfm(req);
507 skcipher_request_free(req);
508 crypto_free_skcipher(tfm);
509 if (ret < 0)
510 pr_err("encrypted_key: failed to encrypt (%d)\n", ret);
511 else
512 dump_encrypted_data(epayload, encrypted_datalen);
513out:
514 return ret;
515}
516
517static int datablob_hmac_append(struct encrypted_key_payload *epayload,
518 const u8 *master_key, size_t master_keylen)
519{
520 u8 derived_key[HASH_SIZE];
521 u8 *digest;
522 int ret;
523
524 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
525 if (ret < 0)
526 goto out;
527
528 digest = epayload->format + epayload->datablob_len;
529 ret = calc_hmac(digest, derived_key, sizeof derived_key,
530 epayload->format, epayload->datablob_len);
531 if (!ret)
532 dump_hmac(NULL, digest, HASH_SIZE);
533out:
534 return ret;
535}
536
537/* verify HMAC before decrypting encrypted key */
538static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
539 const u8 *format, const u8 *master_key,
540 size_t master_keylen)
541{
542 u8 derived_key[HASH_SIZE];
543 u8 digest[HASH_SIZE];
544 int ret;
545 char *p;
546 unsigned short len;
547
548 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
549 if (ret < 0)
550 goto out;
551
552 len = epayload->datablob_len;
553 if (!format) {
554 p = epayload->master_desc;
555 len -= strlen(epayload->format) + 1;
556 } else
557 p = epayload->format;
558
559 ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len);
560 if (ret < 0)
561 goto out;
562 ret = memcmp(digest, epayload->format + epayload->datablob_len,
563 sizeof digest);
564 if (ret) {
565 ret = -EINVAL;
566 dump_hmac("datablob",
567 epayload->format + epayload->datablob_len,
568 HASH_SIZE);
569 dump_hmac("calc", digest, HASH_SIZE);
570 }
571out:
572 return ret;
573}
574
575static int derived_key_decrypt(struct encrypted_key_payload *epayload,
576 const u8 *derived_key,
577 unsigned int derived_keylen)
578{
579 struct scatterlist sg_in[1];
580 struct scatterlist sg_out[2];
581 struct crypto_skcipher *tfm;
582 struct skcipher_request *req;
583 unsigned int encrypted_datalen;
584 char pad[16];
585 int ret;
586
587 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
588 req = init_skcipher_req(derived_key, derived_keylen);
589 ret = PTR_ERR(req);
590 if (IS_ERR(req))
591 goto out;
592 dump_encrypted_data(epayload, encrypted_datalen);
593
594 memset(pad, 0, sizeof pad);
595 sg_init_table(sg_in, 1);
596 sg_init_table(sg_out, 2);
597 sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen);
598 sg_set_buf(&sg_out[0], epayload->decrypted_data,
599 epayload->decrypted_datalen);
600 sg_set_buf(&sg_out[1], pad, sizeof pad);
601
602 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen,
603 epayload->iv);
604 ret = crypto_skcipher_decrypt(req);
605 tfm = crypto_skcipher_reqtfm(req);
606 skcipher_request_free(req);
607 crypto_free_skcipher(tfm);
608 if (ret < 0)
609 goto out;
610 dump_decrypted_data(epayload);
611out:
612 return ret;
613}
614
615/* Allocate memory for decrypted key and datablob. */
616static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
617 const char *format,
618 const char *master_desc,
619 const char *datalen)
620{
621 struct encrypted_key_payload *epayload = NULL;
622 unsigned short datablob_len;
623 unsigned short decrypted_datalen;
624 unsigned short payload_datalen;
625 unsigned int encrypted_datalen;
626 unsigned int format_len;
627 long dlen;
628 int ret;
629
630 ret = kstrtol(datalen, 10, &dlen);
631 if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE)
632 return ERR_PTR(-EINVAL);
633
634 format_len = (!format) ? strlen(key_format_default) : strlen(format);
635 decrypted_datalen = dlen;
636 payload_datalen = decrypted_datalen;
637 if (format && !strcmp(format, key_format_ecryptfs)) {
638 if (dlen != ECRYPTFS_MAX_KEY_BYTES) {
639 pr_err("encrypted_key: keylen for the ecryptfs format "
640 "must be equal to %d bytes\n",
641 ECRYPTFS_MAX_KEY_BYTES);
642 return ERR_PTR(-EINVAL);
643 }
644 decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES;
645 payload_datalen = sizeof(struct ecryptfs_auth_tok);
646 }
647
648 encrypted_datalen = roundup(decrypted_datalen, blksize);
649
650 datablob_len = format_len + 1 + strlen(master_desc) + 1
651 + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen;
652
653 ret = key_payload_reserve(key, payload_datalen + datablob_len
654 + HASH_SIZE + 1);
655 if (ret < 0)
656 return ERR_PTR(ret);
657
658 epayload = kzalloc(sizeof(*epayload) + payload_datalen +
659 datablob_len + HASH_SIZE + 1, GFP_KERNEL);
660 if (!epayload)
661 return ERR_PTR(-ENOMEM);
662
663 epayload->payload_datalen = payload_datalen;
664 epayload->decrypted_datalen = decrypted_datalen;
665 epayload->datablob_len = datablob_len;
666 return epayload;
667}
668
669static int encrypted_key_decrypt(struct encrypted_key_payload *epayload,
670 const char *format, const char *hex_encoded_iv)
671{
672 struct key *mkey;
673 u8 derived_key[HASH_SIZE];
674 const u8 *master_key;
675 u8 *hmac;
676 const char *hex_encoded_data;
677 unsigned int encrypted_datalen;
678 size_t master_keylen;
679 size_t asciilen;
680 int ret;
681
682 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
683 asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2;
684 if (strlen(hex_encoded_iv) != asciilen)
685 return -EINVAL;
686
687 hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2;
688 ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize);
689 if (ret < 0)
690 return -EINVAL;
691 ret = hex2bin(epayload->encrypted_data, hex_encoded_data,
692 encrypted_datalen);
693 if (ret < 0)
694 return -EINVAL;
695
696 hmac = epayload->format + epayload->datablob_len;
697 ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2),
698 HASH_SIZE);
699 if (ret < 0)
700 return -EINVAL;
701
702 mkey = request_master_key(epayload, &master_key, &master_keylen);
703 if (IS_ERR(mkey))
704 return PTR_ERR(mkey);
705
706 ret = datablob_hmac_verify(epayload, format, master_key, master_keylen);
707 if (ret < 0) {
708 pr_err("encrypted_key: bad hmac (%d)\n", ret);
709 goto out;
710 }
711
712 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
713 if (ret < 0)
714 goto out;
715
716 ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key);
717 if (ret < 0)
718 pr_err("encrypted_key: failed to decrypt key (%d)\n", ret);
719out:
720 up_read(&mkey->sem);
721 key_put(mkey);
722 return ret;
723}
724
725static void __ekey_init(struct encrypted_key_payload *epayload,
726 const char *format, const char *master_desc,
727 const char *datalen)
728{
729 unsigned int format_len;
730
731 format_len = (!format) ? strlen(key_format_default) : strlen(format);
732 epayload->format = epayload->payload_data + epayload->payload_datalen;
733 epayload->master_desc = epayload->format + format_len + 1;
734 epayload->datalen = epayload->master_desc + strlen(master_desc) + 1;
735 epayload->iv = epayload->datalen + strlen(datalen) + 1;
736 epayload->encrypted_data = epayload->iv + ivsize + 1;
737 epayload->decrypted_data = epayload->payload_data;
738
739 if (!format)
740 memcpy(epayload->format, key_format_default, format_len);
741 else {
742 if (!strcmp(format, key_format_ecryptfs))
743 epayload->decrypted_data =
744 ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data);
745
746 memcpy(epayload->format, format, format_len);
747 }
748
749 memcpy(epayload->master_desc, master_desc, strlen(master_desc));
750 memcpy(epayload->datalen, datalen, strlen(datalen));
751}
752
753/*
754 * encrypted_init - initialize an encrypted key
755 *
756 * For a new key, use a random number for both the iv and data
757 * itself. For an old key, decrypt the hex encoded data.
758 */
759static int encrypted_init(struct encrypted_key_payload *epayload,
760 const char *key_desc, const char *format,
761 const char *master_desc, const char *datalen,
762 const char *hex_encoded_iv)
763{
764 int ret = 0;
765
766 if (format && !strcmp(format, key_format_ecryptfs)) {
767 ret = valid_ecryptfs_desc(key_desc);
768 if (ret < 0)
769 return ret;
770
771 ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data,
772 key_desc);
773 }
774
775 __ekey_init(epayload, format, master_desc, datalen);
776 if (!hex_encoded_iv) {
777 get_random_bytes(epayload->iv, ivsize);
778
779 get_random_bytes(epayload->decrypted_data,
780 epayload->decrypted_datalen);
781 } else
782 ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv);
783 return ret;
784}
785
786/*
787 * encrypted_instantiate - instantiate an encrypted key
788 *
789 * Decrypt an existing encrypted datablob or create a new encrypted key
790 * based on a kernel random number.
791 *
792 * On success, return 0. Otherwise return errno.
793 */
794static int encrypted_instantiate(struct key *key,
795 struct key_preparsed_payload *prep)
796{
797 struct encrypted_key_payload *epayload = NULL;
798 char *datablob = NULL;
799 const char *format = NULL;
800 char *master_desc = NULL;
801 char *decrypted_datalen = NULL;
802 char *hex_encoded_iv = NULL;
803 size_t datalen = prep->datalen;
804 int ret;
805
806 if (datalen <= 0 || datalen > 32767 || !prep->data)
807 return -EINVAL;
808
809 datablob = kmalloc(datalen + 1, GFP_KERNEL);
810 if (!datablob)
811 return -ENOMEM;
812 datablob[datalen] = 0;
813 memcpy(datablob, prep->data, datalen);
814 ret = datablob_parse(datablob, &format, &master_desc,
815 &decrypted_datalen, &hex_encoded_iv);
816 if (ret < 0)
817 goto out;
818
819 epayload = encrypted_key_alloc(key, format, master_desc,
820 decrypted_datalen);
821 if (IS_ERR(epayload)) {
822 ret = PTR_ERR(epayload);
823 goto out;
824 }
825 ret = encrypted_init(epayload, key->description, format, master_desc,
826 decrypted_datalen, hex_encoded_iv);
827 if (ret < 0) {
828 kfree(epayload);
829 goto out;
830 }
831
832 rcu_assign_keypointer(key, epayload);
833out:
834 kfree(datablob);
835 return ret;
836}
837
838static void encrypted_rcu_free(struct rcu_head *rcu)
839{
840 struct encrypted_key_payload *epayload;
841
842 epayload = container_of(rcu, struct encrypted_key_payload, rcu);
843 memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
844 kfree(epayload);
845}
846
847/*
848 * encrypted_update - update the master key description
849 *
850 * Change the master key description for an existing encrypted key.
851 * The next read will return an encrypted datablob using the new
852 * master key description.
853 *
854 * On success, return 0. Otherwise return errno.
855 */
856static int encrypted_update(struct key *key, struct key_preparsed_payload *prep)
857{
858 struct encrypted_key_payload *epayload = key->payload.data[0];
859 struct encrypted_key_payload *new_epayload;
860 char *buf;
861 char *new_master_desc = NULL;
862 const char *format = NULL;
863 size_t datalen = prep->datalen;
864 int ret = 0;
865
866 if (test_bit(KEY_FLAG_NEGATIVE, &key->flags))
867 return -ENOKEY;
868 if (datalen <= 0 || datalen > 32767 || !prep->data)
869 return -EINVAL;
870
871 buf = kmalloc(datalen + 1, GFP_KERNEL);
872 if (!buf)
873 return -ENOMEM;
874
875 buf[datalen] = 0;
876 memcpy(buf, prep->data, datalen);
877 ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL);
878 if (ret < 0)
879 goto out;
880
881 ret = valid_master_desc(new_master_desc, epayload->master_desc);
882 if (ret < 0)
883 goto out;
884
885 new_epayload = encrypted_key_alloc(key, epayload->format,
886 new_master_desc, epayload->datalen);
887 if (IS_ERR(new_epayload)) {
888 ret = PTR_ERR(new_epayload);
889 goto out;
890 }
891
892 __ekey_init(new_epayload, epayload->format, new_master_desc,
893 epayload->datalen);
894
895 memcpy(new_epayload->iv, epayload->iv, ivsize);
896 memcpy(new_epayload->payload_data, epayload->payload_data,
897 epayload->payload_datalen);
898
899 rcu_assign_keypointer(key, new_epayload);
900 call_rcu(&epayload->rcu, encrypted_rcu_free);
901out:
902 kfree(buf);
903 return ret;
904}
905
906/*
907 * encrypted_read - format and copy the encrypted data to userspace
908 *
909 * The resulting datablob format is:
910 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data>
911 *
912 * On success, return to userspace the encrypted key datablob size.
913 */
914static long encrypted_read(const struct key *key, char __user *buffer,
915 size_t buflen)
916{
917 struct encrypted_key_payload *epayload;
918 struct key *mkey;
919 const u8 *master_key;
920 size_t master_keylen;
921 char derived_key[HASH_SIZE];
922 char *ascii_buf;
923 size_t asciiblob_len;
924 int ret;
925
926 epayload = rcu_dereference_key(key);
927
928 /* returns the hex encoded iv, encrypted-data, and hmac as ascii */
929 asciiblob_len = epayload->datablob_len + ivsize + 1
930 + roundup(epayload->decrypted_datalen, blksize)
931 + (HASH_SIZE * 2);
932
933 if (!buffer || buflen < asciiblob_len)
934 return asciiblob_len;
935
936 mkey = request_master_key(epayload, &master_key, &master_keylen);
937 if (IS_ERR(mkey))
938 return PTR_ERR(mkey);
939
940 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
941 if (ret < 0)
942 goto out;
943
944 ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key);
945 if (ret < 0)
946 goto out;
947
948 ret = datablob_hmac_append(epayload, master_key, master_keylen);
949 if (ret < 0)
950 goto out;
951
952 ascii_buf = datablob_format(epayload, asciiblob_len);
953 if (!ascii_buf) {
954 ret = -ENOMEM;
955 goto out;
956 }
957
958 up_read(&mkey->sem);
959 key_put(mkey);
960
961 if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0)
962 ret = -EFAULT;
963 kfree(ascii_buf);
964
965 return asciiblob_len;
966out:
967 up_read(&mkey->sem);
968 key_put(mkey);
969 return ret;
970}
971
972/*
973 * encrypted_destroy - before freeing the key, clear the decrypted data
974 *
975 * Before freeing the key, clear the memory containing the decrypted
976 * key data.
977 */
978static void encrypted_destroy(struct key *key)
979{
980 struct encrypted_key_payload *epayload = key->payload.data[0];
981
982 if (!epayload)
983 return;
984
985 memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
986 kfree(key->payload.data[0]);
987}
988
989struct key_type key_type_encrypted = {
990 .name = "encrypted",
991 .instantiate = encrypted_instantiate,
992 .update = encrypted_update,
993 .destroy = encrypted_destroy,
994 .describe = user_describe,
995 .read = encrypted_read,
996};
997EXPORT_SYMBOL_GPL(key_type_encrypted);
998
999static void encrypted_shash_release(void)
1000{
1001 if (hashalg)
1002 crypto_free_shash(hashalg);
1003 if (hmacalg)
1004 crypto_free_shash(hmacalg);
1005}
1006
1007static int __init encrypted_shash_alloc(void)
1008{
1009 int ret;
1010
1011 hmacalg = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC);
1012 if (IS_ERR(hmacalg)) {
1013 pr_info("encrypted_key: could not allocate crypto %s\n",
1014 hmac_alg);
1015 return PTR_ERR(hmacalg);
1016 }
1017
1018 hashalg = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC);
1019 if (IS_ERR(hashalg)) {
1020 pr_info("encrypted_key: could not allocate crypto %s\n",
1021 hash_alg);
1022 ret = PTR_ERR(hashalg);
1023 goto hashalg_fail;
1024 }
1025
1026 return 0;
1027
1028hashalg_fail:
1029 crypto_free_shash(hmacalg);
1030 return ret;
1031}
1032
1033static int __init init_encrypted(void)
1034{
1035 int ret;
1036
1037 ret = encrypted_shash_alloc();
1038 if (ret < 0)
1039 return ret;
1040 ret = aes_get_sizes();
1041 if (ret < 0)
1042 goto out;
1043 ret = register_key_type(&key_type_encrypted);
1044 if (ret < 0)
1045 goto out;
1046 return 0;
1047out:
1048 encrypted_shash_release();
1049 return ret;
1050
1051}
1052
1053static void __exit cleanup_encrypted(void)
1054{
1055 encrypted_shash_release();
1056 unregister_key_type(&key_type_encrypted);
1057}
1058
1059late_initcall(init_encrypted);
1060module_exit(cleanup_encrypted);
1061
1062MODULE_LICENSE("GPL");