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/algapi.h>
34 #include <crypto/hash.h>
35 #include <crypto/sha.h>
36 #include <crypto/skcipher.h>
38 #include "encrypted.h"
39 #include "ecryptfs_format.h"
41 static const char KEY_TRUSTED_PREFIX[] = "trusted:";
42 static const char KEY_USER_PREFIX[] = "user:";
43 static const char hash_alg[] = "sha256";
44 static const char hmac_alg[] = "hmac(sha256)";
45 static const char blkcipher_alg[] = "cbc(aes)";
46 static const char key_format_default[] = "default";
47 static const char key_format_ecryptfs[] = "ecryptfs";
48 static unsigned int ivsize;
51 #define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1)
52 #define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1)
53 #define KEY_ECRYPTFS_DESC_LEN 16
54 #define HASH_SIZE SHA256_DIGEST_SIZE
55 #define MAX_DATA_SIZE 4096
56 #define MIN_DATA_SIZE 20
58 static struct crypto_shash *hash_tfm;
61 Opt_err = -1, Opt_new, Opt_load, Opt_update
65 Opt_error = -1, Opt_default, Opt_ecryptfs
68 static const match_table_t key_format_tokens = {
69 {Opt_default, "default"},
70 {Opt_ecryptfs, "ecryptfs"},
74 static const match_table_t key_tokens = {
77 {Opt_update, "update"},
81 static int aes_get_sizes(void)
83 struct crypto_skcipher *tfm;
85 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
87 pr_err("encrypted_key: failed to alloc_cipher (%ld)\n",
91 ivsize = crypto_skcipher_ivsize(tfm);
92 blksize = crypto_skcipher_blocksize(tfm);
93 crypto_free_skcipher(tfm);
98 * valid_ecryptfs_desc - verify the description of a new/loaded encrypted key
100 * The description of a encrypted key with format 'ecryptfs' must contain
101 * exactly 16 hexadecimal characters.
104 static int valid_ecryptfs_desc(const char *ecryptfs_desc)
108 if (strlen(ecryptfs_desc) != KEY_ECRYPTFS_DESC_LEN) {
109 pr_err("encrypted_key: key description must be %d hexadecimal "
110 "characters long\n", KEY_ECRYPTFS_DESC_LEN);
114 for (i = 0; i < KEY_ECRYPTFS_DESC_LEN; i++) {
115 if (!isxdigit(ecryptfs_desc[i])) {
116 pr_err("encrypted_key: key description must contain "
117 "only hexadecimal characters\n");
126 * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key
128 * key-type:= "trusted:" | "user:"
129 * desc:= master-key description
131 * Verify that 'key-type' is valid and that 'desc' exists. On key update,
132 * only the master key description is permitted to change, not the key-type.
133 * The key-type remains constant.
135 * On success returns 0, otherwise -EINVAL.
137 static int valid_master_desc(const char *new_desc, const char *orig_desc)
141 if (!strncmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN))
142 prefix_len = KEY_TRUSTED_PREFIX_LEN;
143 else if (!strncmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN))
144 prefix_len = KEY_USER_PREFIX_LEN;
148 if (!new_desc[prefix_len])
151 if (orig_desc && strncmp(new_desc, orig_desc, prefix_len))
158 * datablob_parse - parse the keyctl data
161 * new [<format>] <master-key name> <decrypted data length>
162 * load [<format>] <master-key name> <decrypted data length>
163 * <encrypted iv + data>
164 * update <new-master-key name>
166 * Tokenizes a copy of the keyctl data, returning a pointer to each token,
167 * which is null terminated.
169 * On success returns 0, otherwise -EINVAL.
171 static int datablob_parse(char *datablob, const char **format,
172 char **master_desc, char **decrypted_datalen,
173 char **hex_encoded_iv)
175 substring_t args[MAX_OPT_ARGS];
181 keyword = strsep(&datablob, " \t");
183 pr_info("encrypted_key: insufficient parameters specified\n");
186 key_cmd = match_token(keyword, key_tokens, args);
188 /* Get optional format: default | ecryptfs */
189 p = strsep(&datablob, " \t");
191 pr_err("encrypted_key: insufficient parameters specified\n");
195 key_format = match_token(p, key_format_tokens, args);
196 switch (key_format) {
200 *master_desc = strsep(&datablob, " \t");
208 pr_info("encrypted_key: master key parameter is missing\n");
212 if (valid_master_desc(*master_desc, NULL) < 0) {
213 pr_info("encrypted_key: master key parameter \'%s\' "
214 "is invalid\n", *master_desc);
218 if (decrypted_datalen) {
219 *decrypted_datalen = strsep(&datablob, " \t");
220 if (!*decrypted_datalen) {
221 pr_info("encrypted_key: keylen parameter is missing\n");
228 if (!decrypted_datalen) {
229 pr_info("encrypted_key: keyword \'%s\' not allowed "
230 "when called from .update method\n", keyword);
236 if (!decrypted_datalen) {
237 pr_info("encrypted_key: keyword \'%s\' not allowed "
238 "when called from .update method\n", keyword);
241 *hex_encoded_iv = strsep(&datablob, " \t");
242 if (!*hex_encoded_iv) {
243 pr_info("encrypted_key: hex blob is missing\n");
249 if (decrypted_datalen) {
250 pr_info("encrypted_key: keyword \'%s\' not allowed "
251 "when called from .instantiate method\n",
258 pr_info("encrypted_key: keyword \'%s\' not recognized\n",
267 * datablob_format - format as an ascii string, before copying to userspace
269 static char *datablob_format(struct encrypted_key_payload *epayload,
270 size_t asciiblob_len)
272 char *ascii_buf, *bufp;
273 u8 *iv = epayload->iv;
277 ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL);
281 ascii_buf[asciiblob_len] = '\0';
283 /* copy datablob master_desc and datalen strings */
284 len = sprintf(ascii_buf, "%s %s %s ", epayload->format,
285 epayload->master_desc, epayload->datalen);
287 /* convert the hex encoded iv, encrypted-data and HMAC to ascii */
288 bufp = &ascii_buf[len];
289 for (i = 0; i < (asciiblob_len - len) / 2; i++)
290 bufp = hex_byte_pack(bufp, iv[i]);
296 * request_user_key - request the user key
298 * Use a user provided key to encrypt/decrypt an encrypted-key.
300 static struct key *request_user_key(const char *master_desc, const u8 **master_key,
301 size_t *master_keylen)
303 const struct user_key_payload *upayload;
306 ukey = request_key(&key_type_user, master_desc, NULL);
310 down_read(&ukey->sem);
311 upayload = user_key_payload_locked(ukey);
312 *master_key = upayload->data;
313 *master_keylen = upayload->datalen;
318 static int calc_hash(struct crypto_shash *tfm, u8 *digest,
319 const u8 *buf, unsigned int buflen)
321 SHASH_DESC_ON_STACK(desc, tfm);
327 err = crypto_shash_digest(desc, buf, buflen, digest);
328 shash_desc_zero(desc);
332 static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen,
333 const u8 *buf, unsigned int buflen)
335 struct crypto_shash *tfm;
338 tfm = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC);
340 pr_err("encrypted_key: can't alloc %s transform: %ld\n",
341 hmac_alg, PTR_ERR(tfm));
345 err = crypto_shash_setkey(tfm, key, keylen);
347 err = calc_hash(tfm, digest, buf, buflen);
348 crypto_free_shash(tfm);
352 enum derived_key_type { ENC_KEY, AUTH_KEY };
354 /* Derive authentication/encryption key from trusted key */
355 static int get_derived_key(u8 *derived_key, enum derived_key_type key_type,
356 const u8 *master_key, size_t master_keylen)
359 unsigned int derived_buf_len;
362 derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen;
363 if (derived_buf_len < HASH_SIZE)
364 derived_buf_len = HASH_SIZE;
366 derived_buf = kzalloc(derived_buf_len, GFP_KERNEL);
371 strcpy(derived_buf, "AUTH_KEY");
373 strcpy(derived_buf, "ENC_KEY");
375 memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
377 ret = calc_hash(hash_tfm, derived_key, derived_buf, derived_buf_len);
382 static struct skcipher_request *init_skcipher_req(const u8 *key,
383 unsigned int key_len)
385 struct skcipher_request *req;
386 struct crypto_skcipher *tfm;
389 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
391 pr_err("encrypted_key: failed to load %s transform (%ld)\n",
392 blkcipher_alg, PTR_ERR(tfm));
393 return ERR_CAST(tfm);
396 ret = crypto_skcipher_setkey(tfm, key, key_len);
398 pr_err("encrypted_key: failed to setkey (%d)\n", ret);
399 crypto_free_skcipher(tfm);
403 req = skcipher_request_alloc(tfm, GFP_KERNEL);
405 pr_err("encrypted_key: failed to allocate request for %s\n",
407 crypto_free_skcipher(tfm);
408 return ERR_PTR(-ENOMEM);
411 skcipher_request_set_callback(req, 0, NULL, NULL);
415 static struct key *request_master_key(struct encrypted_key_payload *epayload,
416 const u8 **master_key, size_t *master_keylen)
418 struct key *mkey = ERR_PTR(-EINVAL);
420 if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX,
421 KEY_TRUSTED_PREFIX_LEN)) {
422 mkey = request_trusted_key(epayload->master_desc +
423 KEY_TRUSTED_PREFIX_LEN,
424 master_key, master_keylen);
425 } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX,
426 KEY_USER_PREFIX_LEN)) {
427 mkey = request_user_key(epayload->master_desc +
429 master_key, master_keylen);
434 int ret = PTR_ERR(mkey);
436 if (ret == -ENOTSUPP)
437 pr_info("encrypted_key: key %s not supported",
438 epayload->master_desc);
440 pr_info("encrypted_key: key %s not found",
441 epayload->master_desc);
445 dump_master_key(*master_key, *master_keylen);
450 /* Before returning data to userspace, encrypt decrypted data. */
451 static int derived_key_encrypt(struct encrypted_key_payload *epayload,
452 const u8 *derived_key,
453 unsigned int derived_keylen)
455 struct scatterlist sg_in[2];
456 struct scatterlist sg_out[1];
457 struct crypto_skcipher *tfm;
458 struct skcipher_request *req;
459 unsigned int encrypted_datalen;
460 u8 iv[AES_BLOCK_SIZE];
463 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
465 req = init_skcipher_req(derived_key, derived_keylen);
469 dump_decrypted_data(epayload);
471 sg_init_table(sg_in, 2);
472 sg_set_buf(&sg_in[0], epayload->decrypted_data,
473 epayload->decrypted_datalen);
474 sg_set_page(&sg_in[1], ZERO_PAGE(0), AES_BLOCK_SIZE, 0);
476 sg_init_table(sg_out, 1);
477 sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
479 memcpy(iv, epayload->iv, sizeof(iv));
480 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
481 ret = crypto_skcipher_encrypt(req);
482 tfm = crypto_skcipher_reqtfm(req);
483 skcipher_request_free(req);
484 crypto_free_skcipher(tfm);
486 pr_err("encrypted_key: failed to encrypt (%d)\n", ret);
488 dump_encrypted_data(epayload, encrypted_datalen);
493 static int datablob_hmac_append(struct encrypted_key_payload *epayload,
494 const u8 *master_key, size_t master_keylen)
496 u8 derived_key[HASH_SIZE];
500 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
504 digest = epayload->format + epayload->datablob_len;
505 ret = calc_hmac(digest, derived_key, sizeof derived_key,
506 epayload->format, epayload->datablob_len);
508 dump_hmac(NULL, digest, HASH_SIZE);
510 memzero_explicit(derived_key, sizeof(derived_key));
514 /* verify HMAC before decrypting encrypted key */
515 static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
516 const u8 *format, const u8 *master_key,
517 size_t master_keylen)
519 u8 derived_key[HASH_SIZE];
520 u8 digest[HASH_SIZE];
525 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
529 len = epayload->datablob_len;
531 p = epayload->master_desc;
532 len -= strlen(epayload->format) + 1;
534 p = epayload->format;
536 ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len);
539 ret = crypto_memneq(digest, epayload->format + epayload->datablob_len,
543 dump_hmac("datablob",
544 epayload->format + epayload->datablob_len,
546 dump_hmac("calc", digest, HASH_SIZE);
549 memzero_explicit(derived_key, sizeof(derived_key));
553 static int derived_key_decrypt(struct encrypted_key_payload *epayload,
554 const u8 *derived_key,
555 unsigned int derived_keylen)
557 struct scatterlist sg_in[1];
558 struct scatterlist sg_out[2];
559 struct crypto_skcipher *tfm;
560 struct skcipher_request *req;
561 unsigned int encrypted_datalen;
562 u8 iv[AES_BLOCK_SIZE];
566 /* Throwaway buffer to hold the unused zero padding at the end */
567 pad = kmalloc(AES_BLOCK_SIZE, GFP_KERNEL);
571 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
572 req = init_skcipher_req(derived_key, derived_keylen);
576 dump_encrypted_data(epayload, encrypted_datalen);
578 sg_init_table(sg_in, 1);
579 sg_init_table(sg_out, 2);
580 sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen);
581 sg_set_buf(&sg_out[0], epayload->decrypted_data,
582 epayload->decrypted_datalen);
583 sg_set_buf(&sg_out[1], pad, AES_BLOCK_SIZE);
585 memcpy(iv, epayload->iv, sizeof(iv));
586 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
587 ret = crypto_skcipher_decrypt(req);
588 tfm = crypto_skcipher_reqtfm(req);
589 skcipher_request_free(req);
590 crypto_free_skcipher(tfm);
593 dump_decrypted_data(epayload);
599 /* Allocate memory for decrypted key and datablob. */
600 static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
602 const char *master_desc,
605 struct encrypted_key_payload *epayload = NULL;
606 unsigned short datablob_len;
607 unsigned short decrypted_datalen;
608 unsigned short payload_datalen;
609 unsigned int encrypted_datalen;
610 unsigned int format_len;
614 ret = kstrtol(datalen, 10, &dlen);
615 if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE)
616 return ERR_PTR(-EINVAL);
618 format_len = (!format) ? strlen(key_format_default) : strlen(format);
619 decrypted_datalen = dlen;
620 payload_datalen = decrypted_datalen;
621 if (format && !strcmp(format, key_format_ecryptfs)) {
622 if (dlen != ECRYPTFS_MAX_KEY_BYTES) {
623 pr_err("encrypted_key: keylen for the ecryptfs format "
624 "must be equal to %d bytes\n",
625 ECRYPTFS_MAX_KEY_BYTES);
626 return ERR_PTR(-EINVAL);
628 decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES;
629 payload_datalen = sizeof(struct ecryptfs_auth_tok);
632 encrypted_datalen = roundup(decrypted_datalen, blksize);
634 datablob_len = format_len + 1 + strlen(master_desc) + 1
635 + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen;
637 ret = key_payload_reserve(key, payload_datalen + datablob_len
642 epayload = kzalloc(sizeof(*epayload) + payload_datalen +
643 datablob_len + HASH_SIZE + 1, GFP_KERNEL);
645 return ERR_PTR(-ENOMEM);
647 epayload->payload_datalen = payload_datalen;
648 epayload->decrypted_datalen = decrypted_datalen;
649 epayload->datablob_len = datablob_len;
653 static int encrypted_key_decrypt(struct encrypted_key_payload *epayload,
654 const char *format, const char *hex_encoded_iv)
657 u8 derived_key[HASH_SIZE];
658 const u8 *master_key;
660 const char *hex_encoded_data;
661 unsigned int encrypted_datalen;
662 size_t master_keylen;
666 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
667 asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2;
668 if (strlen(hex_encoded_iv) != asciilen)
671 hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2;
672 ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize);
675 ret = hex2bin(epayload->encrypted_data, hex_encoded_data,
680 hmac = epayload->format + epayload->datablob_len;
681 ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2),
686 mkey = request_master_key(epayload, &master_key, &master_keylen);
688 return PTR_ERR(mkey);
690 ret = datablob_hmac_verify(epayload, format, master_key, master_keylen);
692 pr_err("encrypted_key: bad hmac (%d)\n", ret);
696 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
700 ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key);
702 pr_err("encrypted_key: failed to decrypt key (%d)\n", ret);
706 memzero_explicit(derived_key, sizeof(derived_key));
710 static void __ekey_init(struct encrypted_key_payload *epayload,
711 const char *format, const char *master_desc,
714 unsigned int format_len;
716 format_len = (!format) ? strlen(key_format_default) : strlen(format);
717 epayload->format = epayload->payload_data + epayload->payload_datalen;
718 epayload->master_desc = epayload->format + format_len + 1;
719 epayload->datalen = epayload->master_desc + strlen(master_desc) + 1;
720 epayload->iv = epayload->datalen + strlen(datalen) + 1;
721 epayload->encrypted_data = epayload->iv + ivsize + 1;
722 epayload->decrypted_data = epayload->payload_data;
725 memcpy(epayload->format, key_format_default, format_len);
727 if (!strcmp(format, key_format_ecryptfs))
728 epayload->decrypted_data =
729 ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data);
731 memcpy(epayload->format, format, format_len);
734 memcpy(epayload->master_desc, master_desc, strlen(master_desc));
735 memcpy(epayload->datalen, datalen, strlen(datalen));
739 * encrypted_init - initialize an encrypted key
741 * For a new key, use a random number for both the iv and data
742 * itself. For an old key, decrypt the hex encoded data.
744 static int encrypted_init(struct encrypted_key_payload *epayload,
745 const char *key_desc, const char *format,
746 const char *master_desc, const char *datalen,
747 const char *hex_encoded_iv)
751 if (format && !strcmp(format, key_format_ecryptfs)) {
752 ret = valid_ecryptfs_desc(key_desc);
756 ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data,
760 __ekey_init(epayload, format, master_desc, datalen);
761 if (!hex_encoded_iv) {
762 get_random_bytes(epayload->iv, ivsize);
764 get_random_bytes(epayload->decrypted_data,
765 epayload->decrypted_datalen);
767 ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv);
772 * encrypted_instantiate - instantiate an encrypted key
774 * Decrypt an existing encrypted datablob or create a new encrypted key
775 * based on a kernel random number.
777 * On success, return 0. Otherwise return errno.
779 static int encrypted_instantiate(struct key *key,
780 struct key_preparsed_payload *prep)
782 struct encrypted_key_payload *epayload = NULL;
783 char *datablob = NULL;
784 const char *format = NULL;
785 char *master_desc = NULL;
786 char *decrypted_datalen = NULL;
787 char *hex_encoded_iv = NULL;
788 size_t datalen = prep->datalen;
791 if (datalen <= 0 || datalen > 32767 || !prep->data)
794 datablob = kmalloc(datalen + 1, GFP_KERNEL);
797 datablob[datalen] = 0;
798 memcpy(datablob, prep->data, datalen);
799 ret = datablob_parse(datablob, &format, &master_desc,
800 &decrypted_datalen, &hex_encoded_iv);
804 epayload = encrypted_key_alloc(key, format, master_desc,
806 if (IS_ERR(epayload)) {
807 ret = PTR_ERR(epayload);
810 ret = encrypted_init(epayload, key->description, format, master_desc,
811 decrypted_datalen, hex_encoded_iv);
817 rcu_assign_keypointer(key, epayload);
823 static void encrypted_rcu_free(struct rcu_head *rcu)
825 struct encrypted_key_payload *epayload;
827 epayload = container_of(rcu, struct encrypted_key_payload, rcu);
832 * encrypted_update - update the master key description
834 * Change the master key description for an existing encrypted key.
835 * The next read will return an encrypted datablob using the new
836 * master key description.
838 * On success, return 0. Otherwise return errno.
840 static int encrypted_update(struct key *key, struct key_preparsed_payload *prep)
842 struct encrypted_key_payload *epayload = key->payload.data[0];
843 struct encrypted_key_payload *new_epayload;
845 char *new_master_desc = NULL;
846 const char *format = NULL;
847 size_t datalen = prep->datalen;
850 if (test_bit(KEY_FLAG_NEGATIVE, &key->flags))
852 if (datalen <= 0 || datalen > 32767 || !prep->data)
855 buf = kmalloc(datalen + 1, GFP_KERNEL);
860 memcpy(buf, prep->data, datalen);
861 ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL);
865 ret = valid_master_desc(new_master_desc, epayload->master_desc);
869 new_epayload = encrypted_key_alloc(key, epayload->format,
870 new_master_desc, epayload->datalen);
871 if (IS_ERR(new_epayload)) {
872 ret = PTR_ERR(new_epayload);
876 __ekey_init(new_epayload, epayload->format, new_master_desc,
879 memcpy(new_epayload->iv, epayload->iv, ivsize);
880 memcpy(new_epayload->payload_data, epayload->payload_data,
881 epayload->payload_datalen);
883 rcu_assign_keypointer(key, new_epayload);
884 call_rcu(&epayload->rcu, encrypted_rcu_free);
891 * encrypted_read - format and copy the encrypted data to userspace
893 * The resulting datablob format is:
894 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data>
896 * On success, return to userspace the encrypted key datablob size.
898 static long encrypted_read(const struct key *key, char __user *buffer,
901 struct encrypted_key_payload *epayload;
903 const u8 *master_key;
904 size_t master_keylen;
905 char derived_key[HASH_SIZE];
907 size_t asciiblob_len;
910 epayload = dereference_key_locked(key);
912 /* returns the hex encoded iv, encrypted-data, and hmac as ascii */
913 asciiblob_len = epayload->datablob_len + ivsize + 1
914 + roundup(epayload->decrypted_datalen, blksize)
917 if (!buffer || buflen < asciiblob_len)
918 return asciiblob_len;
920 mkey = request_master_key(epayload, &master_key, &master_keylen);
922 return PTR_ERR(mkey);
924 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
928 ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key);
932 ret = datablob_hmac_append(epayload, master_key, master_keylen);
936 ascii_buf = datablob_format(epayload, asciiblob_len);
944 memzero_explicit(derived_key, sizeof(derived_key));
946 if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0)
950 return asciiblob_len;
954 memzero_explicit(derived_key, sizeof(derived_key));
959 * encrypted_destroy - clear and free the key's payload
961 static void encrypted_destroy(struct key *key)
963 kzfree(key->payload.data[0]);
966 struct key_type key_type_encrypted = {
968 .instantiate = encrypted_instantiate,
969 .update = encrypted_update,
970 .destroy = encrypted_destroy,
971 .describe = user_describe,
972 .read = encrypted_read,
974 EXPORT_SYMBOL_GPL(key_type_encrypted);
976 static int __init init_encrypted(void)
980 hash_tfm = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC);
981 if (IS_ERR(hash_tfm)) {
982 pr_err("encrypted_key: can't allocate %s transform: %ld\n",
983 hash_alg, PTR_ERR(hash_tfm));
984 return PTR_ERR(hash_tfm);
987 ret = aes_get_sizes();
990 ret = register_key_type(&key_type_encrypted);
995 crypto_free_shash(hash_tfm);
1000 static void __exit cleanup_encrypted(void)
1002 crypto_free_shash(hash_tfm);
1003 unregister_key_type(&key_type_encrypted);
1006 late_initcall(init_encrypted);
1007 module_exit(cleanup_encrypted);
1009 MODULE_LICENSE("GPL");