2 * Copyright (C) 2010 IBM Corporation
3 * Copyright (C) 2010 Politecnico di Torino, Italy
4 * TORSEC group -- http://security.polito.it
7 * Mimi Zohar <zohar@us.ibm.com>
8 * Roberto Sassu <roberto.sassu@polito.it>
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.
14 * See Documentation/security/keys-trusted-encrypted.txt
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/aes.h>
33 #include <crypto/hash.h>
34 #include <crypto/sha.h>
35 #include <crypto/skcipher.h>
37 #include "encrypted.h"
38 #include "ecryptfs_format.h"
40 static const char KEY_TRUSTED_PREFIX[] = "trusted:";
41 static const char KEY_USER_PREFIX[] = "user:";
42 static const char hash_alg[] = "sha256";
43 static const char hmac_alg[] = "hmac(sha256)";
44 static const char blkcipher_alg[] = "cbc(aes)";
45 static const char key_format_default[] = "default";
46 static const char key_format_ecryptfs[] = "ecryptfs";
47 static unsigned int ivsize;
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
58 struct shash_desc shash;
62 static struct crypto_shash *hashalg;
63 static struct crypto_shash *hmacalg;
66 Opt_err = -1, Opt_new, Opt_load, Opt_update
70 Opt_error = -1, Opt_default, Opt_ecryptfs
73 static const match_table_t key_format_tokens = {
74 {Opt_default, "default"},
75 {Opt_ecryptfs, "ecryptfs"},
79 static const match_table_t key_tokens = {
82 {Opt_update, "update"},
86 static int aes_get_sizes(void)
88 struct crypto_skcipher *tfm;
90 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
92 pr_err("encrypted_key: failed to alloc_cipher (%ld)\n",
96 ivsize = crypto_skcipher_ivsize(tfm);
97 blksize = crypto_skcipher_blocksize(tfm);
98 crypto_free_skcipher(tfm);
103 * valid_ecryptfs_desc - verify the description of a new/loaded encrypted key
105 * The description of a encrypted key with format 'ecryptfs' must contain
106 * exactly 16 hexadecimal characters.
109 static int valid_ecryptfs_desc(const char *ecryptfs_desc)
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);
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");
131 * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key
133 * key-type:= "trusted:" | "user:"
134 * desc:= master-key description
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.
140 * On success returns 0, otherwise -EINVAL.
142 static int valid_master_desc(const char *new_desc, const char *orig_desc)
144 if (!memcmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) {
145 if (strlen(new_desc) == KEY_TRUSTED_PREFIX_LEN)
148 if (memcmp(new_desc, orig_desc, KEY_TRUSTED_PREFIX_LEN))
150 } else if (!memcmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) {
151 if (strlen(new_desc) == KEY_USER_PREFIX_LEN)
154 if (memcmp(new_desc, orig_desc, KEY_USER_PREFIX_LEN))
164 * datablob_parse - parse the keyctl data
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>
172 * Tokenizes a copy of the keyctl data, returning a pointer to each token,
173 * which is null terminated.
175 * On success returns 0, otherwise -EINVAL.
177 static int datablob_parse(char *datablob, const char **format,
178 char **master_desc, char **decrypted_datalen,
179 char **hex_encoded_iv)
181 substring_t args[MAX_OPT_ARGS];
187 keyword = strsep(&datablob, " \t");
189 pr_info("encrypted_key: insufficient parameters specified\n");
192 key_cmd = match_token(keyword, key_tokens, args);
194 /* Get optional format: default | ecryptfs */
195 p = strsep(&datablob, " \t");
197 pr_err("encrypted_key: insufficient parameters specified\n");
201 key_format = match_token(p, key_format_tokens, args);
202 switch (key_format) {
206 *master_desc = strsep(&datablob, " \t");
214 pr_info("encrypted_key: master key parameter is missing\n");
218 if (valid_master_desc(*master_desc, NULL) < 0) {
219 pr_info("encrypted_key: master key parameter \'%s\' "
220 "is invalid\n", *master_desc);
224 if (decrypted_datalen) {
225 *decrypted_datalen = strsep(&datablob, " \t");
226 if (!*decrypted_datalen) {
227 pr_info("encrypted_key: keylen parameter is missing\n");
234 if (!decrypted_datalen) {
235 pr_info("encrypted_key: keyword \'%s\' not allowed "
236 "when called from .update method\n", keyword);
242 if (!decrypted_datalen) {
243 pr_info("encrypted_key: keyword \'%s\' not allowed "
244 "when called from .update method\n", keyword);
247 *hex_encoded_iv = strsep(&datablob, " \t");
248 if (!*hex_encoded_iv) {
249 pr_info("encrypted_key: hex blob is missing\n");
255 if (decrypted_datalen) {
256 pr_info("encrypted_key: keyword \'%s\' not allowed "
257 "when called from .instantiate method\n",
264 pr_info("encrypted_key: keyword \'%s\' not recognized\n",
273 * datablob_format - format as an ascii string, before copying to userspace
275 static char *datablob_format(struct encrypted_key_payload *epayload,
276 size_t asciiblob_len)
278 char *ascii_buf, *bufp;
279 u8 *iv = epayload->iv;
283 ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL);
287 ascii_buf[asciiblob_len] = '\0';
289 /* copy datablob master_desc and datalen strings */
290 len = sprintf(ascii_buf, "%s %s %s ", epayload->format,
291 epayload->master_desc, epayload->datalen);
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]);
302 * request_user_key - request the user key
304 * Use a user provided key to encrypt/decrypt an encrypted-key.
306 static struct key *request_user_key(const char *master_desc, const u8 **master_key,
307 size_t *master_keylen)
309 const struct user_key_payload *upayload;
312 ukey = request_key(&key_type_user, master_desc, NULL);
316 down_read(&ukey->sem);
317 upayload = user_key_payload(ukey);
318 *master_key = upayload->data;
319 *master_keylen = upayload->datalen;
324 static struct sdesc *alloc_sdesc(struct crypto_shash *alg)
329 size = sizeof(struct shash_desc) + crypto_shash_descsize(alg);
330 sdesc = kmalloc(size, GFP_KERNEL);
332 return ERR_PTR(-ENOMEM);
333 sdesc->shash.tfm = alg;
334 sdesc->shash.flags = 0x0;
338 static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen,
339 const u8 *buf, unsigned int buflen)
344 sdesc = alloc_sdesc(hmacalg);
346 pr_info("encrypted_key: can't alloc %s\n", hmac_alg);
347 return PTR_ERR(sdesc);
350 ret = crypto_shash_setkey(hmacalg, key, keylen);
352 ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
357 static int calc_hash(u8 *digest, const u8 *buf, unsigned int buflen)
362 sdesc = alloc_sdesc(hashalg);
364 pr_info("encrypted_key: can't alloc %s\n", hash_alg);
365 return PTR_ERR(sdesc);
368 ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
373 enum derived_key_type { ENC_KEY, AUTH_KEY };
375 /* Derive authentication/encryption key from trusted key */
376 static int get_derived_key(u8 *derived_key, enum derived_key_type key_type,
377 const u8 *master_key, size_t master_keylen)
380 unsigned int derived_buf_len;
383 derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen;
384 if (derived_buf_len < HASH_SIZE)
385 derived_buf_len = HASH_SIZE;
387 derived_buf = kzalloc(derived_buf_len, GFP_KERNEL);
389 pr_err("encrypted_key: out of memory\n");
393 strcpy(derived_buf, "AUTH_KEY");
395 strcpy(derived_buf, "ENC_KEY");
397 memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
399 ret = calc_hash(derived_key, derived_buf, derived_buf_len);
404 static struct skcipher_request *init_skcipher_req(const u8 *key,
405 unsigned int key_len)
407 struct skcipher_request *req;
408 struct crypto_skcipher *tfm;
411 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
413 pr_err("encrypted_key: failed to load %s transform (%ld)\n",
414 blkcipher_alg, PTR_ERR(tfm));
415 return ERR_CAST(tfm);
418 ret = crypto_skcipher_setkey(tfm, key, key_len);
420 pr_err("encrypted_key: failed to setkey (%d)\n", ret);
421 crypto_free_skcipher(tfm);
425 req = skcipher_request_alloc(tfm, GFP_KERNEL);
427 pr_err("encrypted_key: failed to allocate request for %s\n",
429 crypto_free_skcipher(tfm);
430 return ERR_PTR(-ENOMEM);
433 skcipher_request_set_callback(req, 0, NULL, NULL);
437 static struct key *request_master_key(struct encrypted_key_payload *epayload,
438 const u8 **master_key, size_t *master_keylen)
440 struct key *mkey = NULL;
442 if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX,
443 KEY_TRUSTED_PREFIX_LEN)) {
444 mkey = request_trusted_key(epayload->master_desc +
445 KEY_TRUSTED_PREFIX_LEN,
446 master_key, master_keylen);
447 } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX,
448 KEY_USER_PREFIX_LEN)) {
449 mkey = request_user_key(epayload->master_desc +
451 master_key, master_keylen);
456 int ret = PTR_ERR(mkey);
458 if (ret == -ENOTSUPP)
459 pr_info("encrypted_key: key %s not supported",
460 epayload->master_desc);
462 pr_info("encrypted_key: key %s not found",
463 epayload->master_desc);
467 dump_master_key(*master_key, *master_keylen);
472 /* Before returning data to userspace, encrypt decrypted data. */
473 static int derived_key_encrypt(struct encrypted_key_payload *epayload,
474 const u8 *derived_key,
475 unsigned int derived_keylen)
477 struct scatterlist sg_in[2];
478 struct scatterlist sg_out[1];
479 struct crypto_skcipher *tfm;
480 struct skcipher_request *req;
481 unsigned int encrypted_datalen;
482 u8 iv[AES_BLOCK_SIZE];
487 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
488 padlen = encrypted_datalen - epayload->decrypted_datalen;
490 req = init_skcipher_req(derived_key, derived_keylen);
494 dump_decrypted_data(epayload);
496 memset(pad, 0, sizeof pad);
497 sg_init_table(sg_in, 2);
498 sg_set_buf(&sg_in[0], epayload->decrypted_data,
499 epayload->decrypted_datalen);
500 sg_set_buf(&sg_in[1], pad, padlen);
502 sg_init_table(sg_out, 1);
503 sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
505 memcpy(iv, epayload->iv, sizeof(iv));
506 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
507 ret = crypto_skcipher_encrypt(req);
508 tfm = crypto_skcipher_reqtfm(req);
509 skcipher_request_free(req);
510 crypto_free_skcipher(tfm);
512 pr_err("encrypted_key: failed to encrypt (%d)\n", ret);
514 dump_encrypted_data(epayload, encrypted_datalen);
519 static int datablob_hmac_append(struct encrypted_key_payload *epayload,
520 const u8 *master_key, size_t master_keylen)
522 u8 derived_key[HASH_SIZE];
526 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
530 digest = epayload->format + epayload->datablob_len;
531 ret = calc_hmac(digest, derived_key, sizeof derived_key,
532 epayload->format, epayload->datablob_len);
534 dump_hmac(NULL, digest, HASH_SIZE);
539 /* verify HMAC before decrypting encrypted key */
540 static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
541 const u8 *format, const u8 *master_key,
542 size_t master_keylen)
544 u8 derived_key[HASH_SIZE];
545 u8 digest[HASH_SIZE];
550 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
554 len = epayload->datablob_len;
556 p = epayload->master_desc;
557 len -= strlen(epayload->format) + 1;
559 p = epayload->format;
561 ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len);
564 ret = memcmp(digest, epayload->format + epayload->datablob_len,
568 dump_hmac("datablob",
569 epayload->format + epayload->datablob_len,
571 dump_hmac("calc", digest, HASH_SIZE);
577 static int derived_key_decrypt(struct encrypted_key_payload *epayload,
578 const u8 *derived_key,
579 unsigned int derived_keylen)
581 struct scatterlist sg_in[1];
582 struct scatterlist sg_out[2];
583 struct crypto_skcipher *tfm;
584 struct skcipher_request *req;
585 unsigned int encrypted_datalen;
586 u8 iv[AES_BLOCK_SIZE];
590 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
591 req = init_skcipher_req(derived_key, derived_keylen);
595 dump_encrypted_data(epayload, encrypted_datalen);
597 memset(pad, 0, sizeof pad);
598 sg_init_table(sg_in, 1);
599 sg_init_table(sg_out, 2);
600 sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen);
601 sg_set_buf(&sg_out[0], epayload->decrypted_data,
602 epayload->decrypted_datalen);
603 sg_set_buf(&sg_out[1], pad, sizeof pad);
605 memcpy(iv, epayload->iv, sizeof(iv));
606 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
607 ret = crypto_skcipher_decrypt(req);
608 tfm = crypto_skcipher_reqtfm(req);
609 skcipher_request_free(req);
610 crypto_free_skcipher(tfm);
613 dump_decrypted_data(epayload);
618 /* Allocate memory for decrypted key and datablob. */
619 static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
621 const char *master_desc,
624 struct encrypted_key_payload *epayload = NULL;
625 unsigned short datablob_len;
626 unsigned short decrypted_datalen;
627 unsigned short payload_datalen;
628 unsigned int encrypted_datalen;
629 unsigned int format_len;
633 ret = kstrtol(datalen, 10, &dlen);
634 if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE)
635 return ERR_PTR(-EINVAL);
637 format_len = (!format) ? strlen(key_format_default) : strlen(format);
638 decrypted_datalen = dlen;
639 payload_datalen = decrypted_datalen;
640 if (format && !strcmp(format, key_format_ecryptfs)) {
641 if (dlen != ECRYPTFS_MAX_KEY_BYTES) {
642 pr_err("encrypted_key: keylen for the ecryptfs format "
643 "must be equal to %d bytes\n",
644 ECRYPTFS_MAX_KEY_BYTES);
645 return ERR_PTR(-EINVAL);
647 decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES;
648 payload_datalen = sizeof(struct ecryptfs_auth_tok);
651 encrypted_datalen = roundup(decrypted_datalen, blksize);
653 datablob_len = format_len + 1 + strlen(master_desc) + 1
654 + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen;
656 ret = key_payload_reserve(key, payload_datalen + datablob_len
661 epayload = kzalloc(sizeof(*epayload) + payload_datalen +
662 datablob_len + HASH_SIZE + 1, GFP_KERNEL);
664 return ERR_PTR(-ENOMEM);
666 epayload->payload_datalen = payload_datalen;
667 epayload->decrypted_datalen = decrypted_datalen;
668 epayload->datablob_len = datablob_len;
672 static int encrypted_key_decrypt(struct encrypted_key_payload *epayload,
673 const char *format, const char *hex_encoded_iv)
676 u8 derived_key[HASH_SIZE];
677 const u8 *master_key;
679 const char *hex_encoded_data;
680 unsigned int encrypted_datalen;
681 size_t master_keylen;
685 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
686 asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2;
687 if (strlen(hex_encoded_iv) != asciilen)
690 hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2;
691 ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize);
694 ret = hex2bin(epayload->encrypted_data, hex_encoded_data,
699 hmac = epayload->format + epayload->datablob_len;
700 ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2),
705 mkey = request_master_key(epayload, &master_key, &master_keylen);
707 return PTR_ERR(mkey);
709 ret = datablob_hmac_verify(epayload, format, master_key, master_keylen);
711 pr_err("encrypted_key: bad hmac (%d)\n", ret);
715 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
719 ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key);
721 pr_err("encrypted_key: failed to decrypt key (%d)\n", ret);
728 static void __ekey_init(struct encrypted_key_payload *epayload,
729 const char *format, const char *master_desc,
732 unsigned int format_len;
734 format_len = (!format) ? strlen(key_format_default) : strlen(format);
735 epayload->format = epayload->payload_data + epayload->payload_datalen;
736 epayload->master_desc = epayload->format + format_len + 1;
737 epayload->datalen = epayload->master_desc + strlen(master_desc) + 1;
738 epayload->iv = epayload->datalen + strlen(datalen) + 1;
739 epayload->encrypted_data = epayload->iv + ivsize + 1;
740 epayload->decrypted_data = epayload->payload_data;
743 memcpy(epayload->format, key_format_default, format_len);
745 if (!strcmp(format, key_format_ecryptfs))
746 epayload->decrypted_data =
747 ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data);
749 memcpy(epayload->format, format, format_len);
752 memcpy(epayload->master_desc, master_desc, strlen(master_desc));
753 memcpy(epayload->datalen, datalen, strlen(datalen));
757 * encrypted_init - initialize an encrypted key
759 * For a new key, use a random number for both the iv and data
760 * itself. For an old key, decrypt the hex encoded data.
762 static int encrypted_init(struct encrypted_key_payload *epayload,
763 const char *key_desc, const char *format,
764 const char *master_desc, const char *datalen,
765 const char *hex_encoded_iv)
769 if (format && !strcmp(format, key_format_ecryptfs)) {
770 ret = valid_ecryptfs_desc(key_desc);
774 ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data,
778 __ekey_init(epayload, format, master_desc, datalen);
779 if (!hex_encoded_iv) {
780 get_random_bytes(epayload->iv, ivsize);
782 get_random_bytes(epayload->decrypted_data,
783 epayload->decrypted_datalen);
785 ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv);
790 * encrypted_instantiate - instantiate an encrypted key
792 * Decrypt an existing encrypted datablob or create a new encrypted key
793 * based on a kernel random number.
795 * On success, return 0. Otherwise return errno.
797 static int encrypted_instantiate(struct key *key,
798 struct key_preparsed_payload *prep)
800 struct encrypted_key_payload *epayload = NULL;
801 char *datablob = NULL;
802 const char *format = NULL;
803 char *master_desc = NULL;
804 char *decrypted_datalen = NULL;
805 char *hex_encoded_iv = NULL;
806 size_t datalen = prep->datalen;
809 if (datalen <= 0 || datalen > 32767 || !prep->data)
812 datablob = kmalloc(datalen + 1, GFP_KERNEL);
815 datablob[datalen] = 0;
816 memcpy(datablob, prep->data, datalen);
817 ret = datablob_parse(datablob, &format, &master_desc,
818 &decrypted_datalen, &hex_encoded_iv);
822 epayload = encrypted_key_alloc(key, format, master_desc,
824 if (IS_ERR(epayload)) {
825 ret = PTR_ERR(epayload);
828 ret = encrypted_init(epayload, key->description, format, master_desc,
829 decrypted_datalen, hex_encoded_iv);
835 rcu_assign_keypointer(key, epayload);
841 static void encrypted_rcu_free(struct rcu_head *rcu)
843 struct encrypted_key_payload *epayload;
845 epayload = container_of(rcu, struct encrypted_key_payload, rcu);
846 memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
851 * encrypted_update - update the master key description
853 * Change the master key description for an existing encrypted key.
854 * The next read will return an encrypted datablob using the new
855 * master key description.
857 * On success, return 0. Otherwise return errno.
859 static int encrypted_update(struct key *key, struct key_preparsed_payload *prep)
861 struct encrypted_key_payload *epayload = key->payload.data[0];
862 struct encrypted_key_payload *new_epayload;
864 char *new_master_desc = NULL;
865 const char *format = NULL;
866 size_t datalen = prep->datalen;
869 if (test_bit(KEY_FLAG_NEGATIVE, &key->flags))
871 if (datalen <= 0 || datalen > 32767 || !prep->data)
874 buf = kmalloc(datalen + 1, GFP_KERNEL);
879 memcpy(buf, prep->data, datalen);
880 ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL);
884 ret = valid_master_desc(new_master_desc, epayload->master_desc);
888 new_epayload = encrypted_key_alloc(key, epayload->format,
889 new_master_desc, epayload->datalen);
890 if (IS_ERR(new_epayload)) {
891 ret = PTR_ERR(new_epayload);
895 __ekey_init(new_epayload, epayload->format, new_master_desc,
898 memcpy(new_epayload->iv, epayload->iv, ivsize);
899 memcpy(new_epayload->payload_data, epayload->payload_data,
900 epayload->payload_datalen);
902 rcu_assign_keypointer(key, new_epayload);
903 call_rcu(&epayload->rcu, encrypted_rcu_free);
910 * encrypted_read - format and copy the encrypted data to userspace
912 * The resulting datablob format is:
913 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data>
915 * On success, return to userspace the encrypted key datablob size.
917 static long encrypted_read(const struct key *key, char __user *buffer,
920 struct encrypted_key_payload *epayload;
922 const u8 *master_key;
923 size_t master_keylen;
924 char derived_key[HASH_SIZE];
926 size_t asciiblob_len;
929 epayload = rcu_dereference_key(key);
931 /* returns the hex encoded iv, encrypted-data, and hmac as ascii */
932 asciiblob_len = epayload->datablob_len + ivsize + 1
933 + roundup(epayload->decrypted_datalen, blksize)
936 if (!buffer || buflen < asciiblob_len)
937 return asciiblob_len;
939 mkey = request_master_key(epayload, &master_key, &master_keylen);
941 return PTR_ERR(mkey);
943 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
947 ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key);
951 ret = datablob_hmac_append(epayload, master_key, master_keylen);
955 ascii_buf = datablob_format(epayload, asciiblob_len);
964 if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0)
968 return asciiblob_len;
976 * encrypted_destroy - before freeing the key, clear the decrypted data
978 * Before freeing the key, clear the memory containing the decrypted
981 static void encrypted_destroy(struct key *key)
983 struct encrypted_key_payload *epayload = key->payload.data[0];
988 memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
989 kfree(key->payload.data[0]);
992 struct key_type key_type_encrypted = {
994 .instantiate = encrypted_instantiate,
995 .update = encrypted_update,
996 .destroy = encrypted_destroy,
997 .describe = user_describe,
998 .read = encrypted_read,
1000 EXPORT_SYMBOL_GPL(key_type_encrypted);
1002 static void encrypted_shash_release(void)
1005 crypto_free_shash(hashalg);
1007 crypto_free_shash(hmacalg);
1010 static int __init encrypted_shash_alloc(void)
1014 hmacalg = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC);
1015 if (IS_ERR(hmacalg)) {
1016 pr_info("encrypted_key: could not allocate crypto %s\n",
1018 return PTR_ERR(hmacalg);
1021 hashalg = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC);
1022 if (IS_ERR(hashalg)) {
1023 pr_info("encrypted_key: could not allocate crypto %s\n",
1025 ret = PTR_ERR(hashalg);
1032 crypto_free_shash(hmacalg);
1036 static int __init init_encrypted(void)
1040 ret = encrypted_shash_alloc();
1043 ret = aes_get_sizes();
1046 ret = register_key_type(&key_type_encrypted);
1051 encrypted_shash_release();
1056 static void __exit cleanup_encrypted(void)
1058 encrypted_shash_release();
1059 unregister_key_type(&key_type_encrypted);
1062 late_initcall(init_encrypted);
1063 module_exit(cleanup_encrypted);
1065 MODULE_LICENSE("GPL");