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)
146 if (!strncmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN))
147 prefix_len = KEY_TRUSTED_PREFIX_LEN;
148 else if (!strncmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN))
149 prefix_len = KEY_USER_PREFIX_LEN;
153 if (!new_desc[prefix_len])
156 if (orig_desc && strncmp(new_desc, orig_desc, prefix_len))
163 * datablob_parse - parse the keyctl data
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>
171 * Tokenizes a copy of the keyctl data, returning a pointer to each token,
172 * which is null terminated.
174 * On success returns 0, otherwise -EINVAL.
176 static int datablob_parse(char *datablob, const char **format,
177 char **master_desc, char **decrypted_datalen,
178 char **hex_encoded_iv)
180 substring_t args[MAX_OPT_ARGS];
186 keyword = strsep(&datablob, " \t");
188 pr_info("encrypted_key: insufficient parameters specified\n");
191 key_cmd = match_token(keyword, key_tokens, args);
193 /* Get optional format: default | ecryptfs */
194 p = strsep(&datablob, " \t");
196 pr_err("encrypted_key: insufficient parameters specified\n");
200 key_format = match_token(p, key_format_tokens, args);
201 switch (key_format) {
205 *master_desc = strsep(&datablob, " \t");
213 pr_info("encrypted_key: master key parameter is missing\n");
217 if (valid_master_desc(*master_desc, NULL) < 0) {
218 pr_info("encrypted_key: master key parameter \'%s\' "
219 "is invalid\n", *master_desc);
223 if (decrypted_datalen) {
224 *decrypted_datalen = strsep(&datablob, " \t");
225 if (!*decrypted_datalen) {
226 pr_info("encrypted_key: keylen parameter is missing\n");
233 if (!decrypted_datalen) {
234 pr_info("encrypted_key: keyword \'%s\' not allowed "
235 "when called from .update method\n", keyword);
241 if (!decrypted_datalen) {
242 pr_info("encrypted_key: keyword \'%s\' not allowed "
243 "when called from .update method\n", keyword);
246 *hex_encoded_iv = strsep(&datablob, " \t");
247 if (!*hex_encoded_iv) {
248 pr_info("encrypted_key: hex blob is missing\n");
254 if (decrypted_datalen) {
255 pr_info("encrypted_key: keyword \'%s\' not allowed "
256 "when called from .instantiate method\n",
263 pr_info("encrypted_key: keyword \'%s\' not recognized\n",
272 * datablob_format - format as an ascii string, before copying to userspace
274 static char *datablob_format(struct encrypted_key_payload *epayload,
275 size_t asciiblob_len)
277 char *ascii_buf, *bufp;
278 u8 *iv = epayload->iv;
282 ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL);
286 ascii_buf[asciiblob_len] = '\0';
288 /* copy datablob master_desc and datalen strings */
289 len = sprintf(ascii_buf, "%s %s %s ", epayload->format,
290 epayload->master_desc, epayload->datalen);
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]);
301 * request_user_key - request the user key
303 * Use a user provided key to encrypt/decrypt an encrypted-key.
305 static struct key *request_user_key(const char *master_desc, const u8 **master_key,
306 size_t *master_keylen)
308 const struct user_key_payload *upayload;
311 ukey = request_key(&key_type_user, master_desc, NULL);
315 down_read(&ukey->sem);
316 upayload = user_key_payload_locked(ukey);
317 *master_key = upayload->data;
318 *master_keylen = upayload->datalen;
323 static struct sdesc *alloc_sdesc(struct crypto_shash *alg)
328 size = sizeof(struct shash_desc) + crypto_shash_descsize(alg);
329 sdesc = kmalloc(size, GFP_KERNEL);
331 return ERR_PTR(-ENOMEM);
332 sdesc->shash.tfm = alg;
333 sdesc->shash.flags = 0x0;
337 static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen,
338 const u8 *buf, unsigned int buflen)
343 sdesc = alloc_sdesc(hmacalg);
345 pr_info("encrypted_key: can't alloc %s\n", hmac_alg);
346 return PTR_ERR(sdesc);
349 ret = crypto_shash_setkey(hmacalg, key, keylen);
351 ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
356 static int calc_hash(u8 *digest, const u8 *buf, unsigned int buflen)
361 sdesc = alloc_sdesc(hashalg);
363 pr_info("encrypted_key: can't alloc %s\n", hash_alg);
364 return PTR_ERR(sdesc);
367 ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
372 enum derived_key_type { ENC_KEY, AUTH_KEY };
374 /* Derive authentication/encryption key from trusted key */
375 static int get_derived_key(u8 *derived_key, enum derived_key_type key_type,
376 const u8 *master_key, size_t master_keylen)
379 unsigned int derived_buf_len;
382 derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen;
383 if (derived_buf_len < HASH_SIZE)
384 derived_buf_len = HASH_SIZE;
386 derived_buf = kzalloc(derived_buf_len, GFP_KERNEL);
391 strcpy(derived_buf, "AUTH_KEY");
393 strcpy(derived_buf, "ENC_KEY");
395 memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
397 ret = calc_hash(derived_key, derived_buf, derived_buf_len);
402 static struct skcipher_request *init_skcipher_req(const u8 *key,
403 unsigned int key_len)
405 struct skcipher_request *req;
406 struct crypto_skcipher *tfm;
409 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
411 pr_err("encrypted_key: failed to load %s transform (%ld)\n",
412 blkcipher_alg, PTR_ERR(tfm));
413 return ERR_CAST(tfm);
416 ret = crypto_skcipher_setkey(tfm, key, key_len);
418 pr_err("encrypted_key: failed to setkey (%d)\n", ret);
419 crypto_free_skcipher(tfm);
423 req = skcipher_request_alloc(tfm, GFP_KERNEL);
425 pr_err("encrypted_key: failed to allocate request for %s\n",
427 crypto_free_skcipher(tfm);
428 return ERR_PTR(-ENOMEM);
431 skcipher_request_set_callback(req, 0, NULL, NULL);
435 static struct key *request_master_key(struct encrypted_key_payload *epayload,
436 const u8 **master_key, size_t *master_keylen)
438 struct key *mkey = ERR_PTR(-EINVAL);
440 if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX,
441 KEY_TRUSTED_PREFIX_LEN)) {
442 mkey = request_trusted_key(epayload->master_desc +
443 KEY_TRUSTED_PREFIX_LEN,
444 master_key, master_keylen);
445 } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX,
446 KEY_USER_PREFIX_LEN)) {
447 mkey = request_user_key(epayload->master_desc +
449 master_key, master_keylen);
454 int ret = PTR_ERR(mkey);
456 if (ret == -ENOTSUPP)
457 pr_info("encrypted_key: key %s not supported",
458 epayload->master_desc);
460 pr_info("encrypted_key: key %s not found",
461 epayload->master_desc);
465 dump_master_key(*master_key, *master_keylen);
470 /* Before returning data to userspace, encrypt decrypted data. */
471 static int derived_key_encrypt(struct encrypted_key_payload *epayload,
472 const u8 *derived_key,
473 unsigned int derived_keylen)
475 struct scatterlist sg_in[2];
476 struct scatterlist sg_out[1];
477 struct crypto_skcipher *tfm;
478 struct skcipher_request *req;
479 unsigned int encrypted_datalen;
480 u8 iv[AES_BLOCK_SIZE];
483 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
485 req = init_skcipher_req(derived_key, derived_keylen);
489 dump_decrypted_data(epayload);
491 sg_init_table(sg_in, 2);
492 sg_set_buf(&sg_in[0], epayload->decrypted_data,
493 epayload->decrypted_datalen);
494 sg_set_page(&sg_in[1], ZERO_PAGE(0), AES_BLOCK_SIZE, 0);
496 sg_init_table(sg_out, 1);
497 sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
499 memcpy(iv, epayload->iv, sizeof(iv));
500 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
501 ret = crypto_skcipher_encrypt(req);
502 tfm = crypto_skcipher_reqtfm(req);
503 skcipher_request_free(req);
504 crypto_free_skcipher(tfm);
506 pr_err("encrypted_key: failed to encrypt (%d)\n", ret);
508 dump_encrypted_data(epayload, encrypted_datalen);
513 static int datablob_hmac_append(struct encrypted_key_payload *epayload,
514 const u8 *master_key, size_t master_keylen)
516 u8 derived_key[HASH_SIZE];
520 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
524 digest = epayload->format + epayload->datablob_len;
525 ret = calc_hmac(digest, derived_key, sizeof derived_key,
526 epayload->format, epayload->datablob_len);
528 dump_hmac(NULL, digest, HASH_SIZE);
533 /* verify HMAC before decrypting encrypted key */
534 static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
535 const u8 *format, const u8 *master_key,
536 size_t master_keylen)
538 u8 derived_key[HASH_SIZE];
539 u8 digest[HASH_SIZE];
544 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
548 len = epayload->datablob_len;
550 p = epayload->master_desc;
551 len -= strlen(epayload->format) + 1;
553 p = epayload->format;
555 ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len);
558 ret = memcmp(digest, epayload->format + epayload->datablob_len,
562 dump_hmac("datablob",
563 epayload->format + epayload->datablob_len,
565 dump_hmac("calc", digest, HASH_SIZE);
571 static int derived_key_decrypt(struct encrypted_key_payload *epayload,
572 const u8 *derived_key,
573 unsigned int derived_keylen)
575 struct scatterlist sg_in[1];
576 struct scatterlist sg_out[2];
577 struct crypto_skcipher *tfm;
578 struct skcipher_request *req;
579 unsigned int encrypted_datalen;
580 u8 iv[AES_BLOCK_SIZE];
584 /* Throwaway buffer to hold the unused zero padding at the end */
585 pad = kmalloc(AES_BLOCK_SIZE, GFP_KERNEL);
589 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
590 req = init_skcipher_req(derived_key, derived_keylen);
594 dump_encrypted_data(epayload, encrypted_datalen);
596 sg_init_table(sg_in, 1);
597 sg_init_table(sg_out, 2);
598 sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen);
599 sg_set_buf(&sg_out[0], epayload->decrypted_data,
600 epayload->decrypted_datalen);
601 sg_set_buf(&sg_out[1], pad, AES_BLOCK_SIZE);
603 memcpy(iv, epayload->iv, sizeof(iv));
604 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
605 ret = crypto_skcipher_decrypt(req);
606 tfm = crypto_skcipher_reqtfm(req);
607 skcipher_request_free(req);
608 crypto_free_skcipher(tfm);
611 dump_decrypted_data(epayload);
617 /* Allocate memory for decrypted key and datablob. */
618 static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
620 const char *master_desc,
623 struct encrypted_key_payload *epayload = NULL;
624 unsigned short datablob_len;
625 unsigned short decrypted_datalen;
626 unsigned short payload_datalen;
627 unsigned int encrypted_datalen;
628 unsigned int format_len;
632 ret = kstrtol(datalen, 10, &dlen);
633 if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE)
634 return ERR_PTR(-EINVAL);
636 format_len = (!format) ? strlen(key_format_default) : strlen(format);
637 decrypted_datalen = dlen;
638 payload_datalen = decrypted_datalen;
639 if (format && !strcmp(format, key_format_ecryptfs)) {
640 if (dlen != ECRYPTFS_MAX_KEY_BYTES) {
641 pr_err("encrypted_key: keylen for the ecryptfs format "
642 "must be equal to %d bytes\n",
643 ECRYPTFS_MAX_KEY_BYTES);
644 return ERR_PTR(-EINVAL);
646 decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES;
647 payload_datalen = sizeof(struct ecryptfs_auth_tok);
650 encrypted_datalen = roundup(decrypted_datalen, blksize);
652 datablob_len = format_len + 1 + strlen(master_desc) + 1
653 + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen;
655 ret = key_payload_reserve(key, payload_datalen + datablob_len
660 epayload = kzalloc(sizeof(*epayload) + payload_datalen +
661 datablob_len + HASH_SIZE + 1, GFP_KERNEL);
663 return ERR_PTR(-ENOMEM);
665 epayload->payload_datalen = payload_datalen;
666 epayload->decrypted_datalen = decrypted_datalen;
667 epayload->datablob_len = datablob_len;
671 static int encrypted_key_decrypt(struct encrypted_key_payload *epayload,
672 const char *format, const char *hex_encoded_iv)
675 u8 derived_key[HASH_SIZE];
676 const u8 *master_key;
678 const char *hex_encoded_data;
679 unsigned int encrypted_datalen;
680 size_t master_keylen;
684 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
685 asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2;
686 if (strlen(hex_encoded_iv) != asciilen)
689 hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2;
690 ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize);
693 ret = hex2bin(epayload->encrypted_data, hex_encoded_data,
698 hmac = epayload->format + epayload->datablob_len;
699 ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2),
704 mkey = request_master_key(epayload, &master_key, &master_keylen);
706 return PTR_ERR(mkey);
708 ret = datablob_hmac_verify(epayload, format, master_key, master_keylen);
710 pr_err("encrypted_key: bad hmac (%d)\n", ret);
714 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
718 ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key);
720 pr_err("encrypted_key: failed to decrypt key (%d)\n", ret);
727 static void __ekey_init(struct encrypted_key_payload *epayload,
728 const char *format, const char *master_desc,
731 unsigned int format_len;
733 format_len = (!format) ? strlen(key_format_default) : strlen(format);
734 epayload->format = epayload->payload_data + epayload->payload_datalen;
735 epayload->master_desc = epayload->format + format_len + 1;
736 epayload->datalen = epayload->master_desc + strlen(master_desc) + 1;
737 epayload->iv = epayload->datalen + strlen(datalen) + 1;
738 epayload->encrypted_data = epayload->iv + ivsize + 1;
739 epayload->decrypted_data = epayload->payload_data;
742 memcpy(epayload->format, key_format_default, format_len);
744 if (!strcmp(format, key_format_ecryptfs))
745 epayload->decrypted_data =
746 ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data);
748 memcpy(epayload->format, format, format_len);
751 memcpy(epayload->master_desc, master_desc, strlen(master_desc));
752 memcpy(epayload->datalen, datalen, strlen(datalen));
756 * encrypted_init - initialize an encrypted key
758 * For a new key, use a random number for both the iv and data
759 * itself. For an old key, decrypt the hex encoded data.
761 static int encrypted_init(struct encrypted_key_payload *epayload,
762 const char *key_desc, const char *format,
763 const char *master_desc, const char *datalen,
764 const char *hex_encoded_iv)
768 if (format && !strcmp(format, key_format_ecryptfs)) {
769 ret = valid_ecryptfs_desc(key_desc);
773 ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data,
777 __ekey_init(epayload, format, master_desc, datalen);
778 if (!hex_encoded_iv) {
779 get_random_bytes(epayload->iv, ivsize);
781 get_random_bytes(epayload->decrypted_data,
782 epayload->decrypted_datalen);
784 ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv);
789 * encrypted_instantiate - instantiate an encrypted key
791 * Decrypt an existing encrypted datablob or create a new encrypted key
792 * based on a kernel random number.
794 * On success, return 0. Otherwise return errno.
796 static int encrypted_instantiate(struct key *key,
797 struct key_preparsed_payload *prep)
799 struct encrypted_key_payload *epayload = NULL;
800 char *datablob = NULL;
801 const char *format = NULL;
802 char *master_desc = NULL;
803 char *decrypted_datalen = NULL;
804 char *hex_encoded_iv = NULL;
805 size_t datalen = prep->datalen;
808 if (datalen <= 0 || datalen > 32767 || !prep->data)
811 datablob = kmalloc(datalen + 1, GFP_KERNEL);
814 datablob[datalen] = 0;
815 memcpy(datablob, prep->data, datalen);
816 ret = datablob_parse(datablob, &format, &master_desc,
817 &decrypted_datalen, &hex_encoded_iv);
821 epayload = encrypted_key_alloc(key, format, master_desc,
823 if (IS_ERR(epayload)) {
824 ret = PTR_ERR(epayload);
827 ret = encrypted_init(epayload, key->description, format, master_desc,
828 decrypted_datalen, hex_encoded_iv);
834 rcu_assign_keypointer(key, epayload);
840 static void encrypted_rcu_free(struct rcu_head *rcu)
842 struct encrypted_key_payload *epayload;
844 epayload = container_of(rcu, struct encrypted_key_payload, rcu);
845 memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
850 * encrypted_update - update the master key description
852 * Change the master key description for an existing encrypted key.
853 * The next read will return an encrypted datablob using the new
854 * master key description.
856 * On success, return 0. Otherwise return errno.
858 static int encrypted_update(struct key *key, struct key_preparsed_payload *prep)
860 struct encrypted_key_payload *epayload = key->payload.data[0];
861 struct encrypted_key_payload *new_epayload;
863 char *new_master_desc = NULL;
864 const char *format = NULL;
865 size_t datalen = prep->datalen;
868 if (test_bit(KEY_FLAG_NEGATIVE, &key->flags))
870 if (datalen <= 0 || datalen > 32767 || !prep->data)
873 buf = kmalloc(datalen + 1, GFP_KERNEL);
878 memcpy(buf, prep->data, datalen);
879 ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL);
883 ret = valid_master_desc(new_master_desc, epayload->master_desc);
887 new_epayload = encrypted_key_alloc(key, epayload->format,
888 new_master_desc, epayload->datalen);
889 if (IS_ERR(new_epayload)) {
890 ret = PTR_ERR(new_epayload);
894 __ekey_init(new_epayload, epayload->format, new_master_desc,
897 memcpy(new_epayload->iv, epayload->iv, ivsize);
898 memcpy(new_epayload->payload_data, epayload->payload_data,
899 epayload->payload_datalen);
901 rcu_assign_keypointer(key, new_epayload);
902 call_rcu(&epayload->rcu, encrypted_rcu_free);
909 * encrypted_read - format and copy the encrypted data to userspace
911 * The resulting datablob format is:
912 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data>
914 * On success, return to userspace the encrypted key datablob size.
916 static long encrypted_read(const struct key *key, char __user *buffer,
919 struct encrypted_key_payload *epayload;
921 const u8 *master_key;
922 size_t master_keylen;
923 char derived_key[HASH_SIZE];
925 size_t asciiblob_len;
928 epayload = dereference_key_locked(key);
930 /* returns the hex encoded iv, encrypted-data, and hmac as ascii */
931 asciiblob_len = epayload->datablob_len + ivsize + 1
932 + roundup(epayload->decrypted_datalen, blksize)
935 if (!buffer || buflen < asciiblob_len)
936 return asciiblob_len;
938 mkey = request_master_key(epayload, &master_key, &master_keylen);
940 return PTR_ERR(mkey);
942 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
946 ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key);
950 ret = datablob_hmac_append(epayload, master_key, master_keylen);
954 ascii_buf = datablob_format(epayload, asciiblob_len);
963 if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0)
967 return asciiblob_len;
975 * encrypted_destroy - before freeing the key, clear the decrypted data
977 * Before freeing the key, clear the memory containing the decrypted
980 static void encrypted_destroy(struct key *key)
982 struct encrypted_key_payload *epayload = key->payload.data[0];
987 memzero_explicit(epayload->decrypted_data, epayload->decrypted_datalen);
988 kfree(key->payload.data[0]);
991 struct key_type key_type_encrypted = {
993 .instantiate = encrypted_instantiate,
994 .update = encrypted_update,
995 .destroy = encrypted_destroy,
996 .describe = user_describe,
997 .read = encrypted_read,
999 EXPORT_SYMBOL_GPL(key_type_encrypted);
1001 static void encrypted_shash_release(void)
1004 crypto_free_shash(hashalg);
1006 crypto_free_shash(hmacalg);
1009 static int __init encrypted_shash_alloc(void)
1013 hmacalg = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC);
1014 if (IS_ERR(hmacalg)) {
1015 pr_info("encrypted_key: could not allocate crypto %s\n",
1017 return PTR_ERR(hmacalg);
1020 hashalg = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC);
1021 if (IS_ERR(hashalg)) {
1022 pr_info("encrypted_key: could not allocate crypto %s\n",
1024 ret = PTR_ERR(hashalg);
1031 crypto_free_shash(hmacalg);
1035 static int __init init_encrypted(void)
1039 ret = encrypted_shash_alloc();
1042 ret = aes_get_sizes();
1045 ret = register_key_type(&key_type_encrypted);
1050 encrypted_shash_release();
1055 static void __exit cleanup_encrypted(void)
1057 encrypted_shash_release();
1058 unregister_key_type(&key_type_encrypted);
1061 late_initcall(init_encrypted);
1062 module_exit(cleanup_encrypted);
1064 MODULE_LICENSE("GPL");