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.rst
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);
313 /* key was revoked before we acquired its semaphore */
316 ukey = ERR_PTR(-EKEYREVOKED);
319 *master_key = upayload->data;
320 *master_keylen = upayload->datalen;
325 static int calc_hash(struct crypto_shash *tfm, u8 *digest,
326 const u8 *buf, unsigned int buflen)
328 SHASH_DESC_ON_STACK(desc, tfm);
334 err = crypto_shash_digest(desc, buf, buflen, digest);
335 shash_desc_zero(desc);
339 static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen,
340 const u8 *buf, unsigned int buflen)
342 struct crypto_shash *tfm;
345 tfm = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC);
347 pr_err("encrypted_key: can't alloc %s transform: %ld\n",
348 hmac_alg, PTR_ERR(tfm));
352 err = crypto_shash_setkey(tfm, key, keylen);
354 err = calc_hash(tfm, digest, buf, buflen);
355 crypto_free_shash(tfm);
359 enum derived_key_type { ENC_KEY, AUTH_KEY };
361 /* Derive authentication/encryption key from trusted key */
362 static int get_derived_key(u8 *derived_key, enum derived_key_type key_type,
363 const u8 *master_key, size_t master_keylen)
366 unsigned int derived_buf_len;
369 derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen;
370 if (derived_buf_len < HASH_SIZE)
371 derived_buf_len = HASH_SIZE;
373 derived_buf = kzalloc(derived_buf_len, GFP_KERNEL);
378 strcpy(derived_buf, "AUTH_KEY");
380 strcpy(derived_buf, "ENC_KEY");
382 memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
384 ret = calc_hash(hash_tfm, derived_key, derived_buf, derived_buf_len);
389 static struct skcipher_request *init_skcipher_req(const u8 *key,
390 unsigned int key_len)
392 struct skcipher_request *req;
393 struct crypto_skcipher *tfm;
396 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
398 pr_err("encrypted_key: failed to load %s transform (%ld)\n",
399 blkcipher_alg, PTR_ERR(tfm));
400 return ERR_CAST(tfm);
403 ret = crypto_skcipher_setkey(tfm, key, key_len);
405 pr_err("encrypted_key: failed to setkey (%d)\n", ret);
406 crypto_free_skcipher(tfm);
410 req = skcipher_request_alloc(tfm, GFP_KERNEL);
412 pr_err("encrypted_key: failed to allocate request for %s\n",
414 crypto_free_skcipher(tfm);
415 return ERR_PTR(-ENOMEM);
418 skcipher_request_set_callback(req, 0, NULL, NULL);
422 static struct key *request_master_key(struct encrypted_key_payload *epayload,
423 const u8 **master_key, size_t *master_keylen)
425 struct key *mkey = ERR_PTR(-EINVAL);
427 if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX,
428 KEY_TRUSTED_PREFIX_LEN)) {
429 mkey = request_trusted_key(epayload->master_desc +
430 KEY_TRUSTED_PREFIX_LEN,
431 master_key, master_keylen);
432 } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX,
433 KEY_USER_PREFIX_LEN)) {
434 mkey = request_user_key(epayload->master_desc +
436 master_key, master_keylen);
441 int ret = PTR_ERR(mkey);
443 if (ret == -ENOTSUPP)
444 pr_info("encrypted_key: key %s not supported",
445 epayload->master_desc);
447 pr_info("encrypted_key: key %s not found",
448 epayload->master_desc);
452 dump_master_key(*master_key, *master_keylen);
457 /* Before returning data to userspace, encrypt decrypted data. */
458 static int derived_key_encrypt(struct encrypted_key_payload *epayload,
459 const u8 *derived_key,
460 unsigned int derived_keylen)
462 struct scatterlist sg_in[2];
463 struct scatterlist sg_out[1];
464 struct crypto_skcipher *tfm;
465 struct skcipher_request *req;
466 unsigned int encrypted_datalen;
467 u8 iv[AES_BLOCK_SIZE];
470 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
472 req = init_skcipher_req(derived_key, derived_keylen);
476 dump_decrypted_data(epayload);
478 sg_init_table(sg_in, 2);
479 sg_set_buf(&sg_in[0], epayload->decrypted_data,
480 epayload->decrypted_datalen);
481 sg_set_page(&sg_in[1], ZERO_PAGE(0), AES_BLOCK_SIZE, 0);
483 sg_init_table(sg_out, 1);
484 sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
486 memcpy(iv, epayload->iv, sizeof(iv));
487 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
488 ret = crypto_skcipher_encrypt(req);
489 tfm = crypto_skcipher_reqtfm(req);
490 skcipher_request_free(req);
491 crypto_free_skcipher(tfm);
493 pr_err("encrypted_key: failed to encrypt (%d)\n", ret);
495 dump_encrypted_data(epayload, encrypted_datalen);
500 static int datablob_hmac_append(struct encrypted_key_payload *epayload,
501 const u8 *master_key, size_t master_keylen)
503 u8 derived_key[HASH_SIZE];
507 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
511 digest = epayload->format + epayload->datablob_len;
512 ret = calc_hmac(digest, derived_key, sizeof derived_key,
513 epayload->format, epayload->datablob_len);
515 dump_hmac(NULL, digest, HASH_SIZE);
517 memzero_explicit(derived_key, sizeof(derived_key));
521 /* verify HMAC before decrypting encrypted key */
522 static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
523 const u8 *format, const u8 *master_key,
524 size_t master_keylen)
526 u8 derived_key[HASH_SIZE];
527 u8 digest[HASH_SIZE];
532 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
536 len = epayload->datablob_len;
538 p = epayload->master_desc;
539 len -= strlen(epayload->format) + 1;
541 p = epayload->format;
543 ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len);
546 ret = crypto_memneq(digest, epayload->format + epayload->datablob_len,
550 dump_hmac("datablob",
551 epayload->format + epayload->datablob_len,
553 dump_hmac("calc", digest, HASH_SIZE);
556 memzero_explicit(derived_key, sizeof(derived_key));
560 static int derived_key_decrypt(struct encrypted_key_payload *epayload,
561 const u8 *derived_key,
562 unsigned int derived_keylen)
564 struct scatterlist sg_in[1];
565 struct scatterlist sg_out[2];
566 struct crypto_skcipher *tfm;
567 struct skcipher_request *req;
568 unsigned int encrypted_datalen;
569 u8 iv[AES_BLOCK_SIZE];
573 /* Throwaway buffer to hold the unused zero padding at the end */
574 pad = kmalloc(AES_BLOCK_SIZE, GFP_KERNEL);
578 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
579 req = init_skcipher_req(derived_key, derived_keylen);
583 dump_encrypted_data(epayload, encrypted_datalen);
585 sg_init_table(sg_in, 1);
586 sg_init_table(sg_out, 2);
587 sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen);
588 sg_set_buf(&sg_out[0], epayload->decrypted_data,
589 epayload->decrypted_datalen);
590 sg_set_buf(&sg_out[1], pad, AES_BLOCK_SIZE);
592 memcpy(iv, epayload->iv, sizeof(iv));
593 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
594 ret = crypto_skcipher_decrypt(req);
595 tfm = crypto_skcipher_reqtfm(req);
596 skcipher_request_free(req);
597 crypto_free_skcipher(tfm);
600 dump_decrypted_data(epayload);
606 /* Allocate memory for decrypted key and datablob. */
607 static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
609 const char *master_desc,
612 struct encrypted_key_payload *epayload = NULL;
613 unsigned short datablob_len;
614 unsigned short decrypted_datalen;
615 unsigned short payload_datalen;
616 unsigned int encrypted_datalen;
617 unsigned int format_len;
621 ret = kstrtol(datalen, 10, &dlen);
622 if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE)
623 return ERR_PTR(-EINVAL);
625 format_len = (!format) ? strlen(key_format_default) : strlen(format);
626 decrypted_datalen = dlen;
627 payload_datalen = decrypted_datalen;
628 if (format && !strcmp(format, key_format_ecryptfs)) {
629 if (dlen != ECRYPTFS_MAX_KEY_BYTES) {
630 pr_err("encrypted_key: keylen for the ecryptfs format "
631 "must be equal to %d bytes\n",
632 ECRYPTFS_MAX_KEY_BYTES);
633 return ERR_PTR(-EINVAL);
635 decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES;
636 payload_datalen = sizeof(struct ecryptfs_auth_tok);
639 encrypted_datalen = roundup(decrypted_datalen, blksize);
641 datablob_len = format_len + 1 + strlen(master_desc) + 1
642 + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen;
644 ret = key_payload_reserve(key, payload_datalen + datablob_len
649 epayload = kzalloc(sizeof(*epayload) + payload_datalen +
650 datablob_len + HASH_SIZE + 1, GFP_KERNEL);
652 return ERR_PTR(-ENOMEM);
654 epayload->payload_datalen = payload_datalen;
655 epayload->decrypted_datalen = decrypted_datalen;
656 epayload->datablob_len = datablob_len;
660 static int encrypted_key_decrypt(struct encrypted_key_payload *epayload,
661 const char *format, const char *hex_encoded_iv)
664 u8 derived_key[HASH_SIZE];
665 const u8 *master_key;
667 const char *hex_encoded_data;
668 unsigned int encrypted_datalen;
669 size_t master_keylen;
673 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
674 asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2;
675 if (strlen(hex_encoded_iv) != asciilen)
678 hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2;
679 ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize);
682 ret = hex2bin(epayload->encrypted_data, hex_encoded_data,
687 hmac = epayload->format + epayload->datablob_len;
688 ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2),
693 mkey = request_master_key(epayload, &master_key, &master_keylen);
695 return PTR_ERR(mkey);
697 ret = datablob_hmac_verify(epayload, format, master_key, master_keylen);
699 pr_err("encrypted_key: bad hmac (%d)\n", ret);
703 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
707 ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key);
709 pr_err("encrypted_key: failed to decrypt key (%d)\n", ret);
713 memzero_explicit(derived_key, sizeof(derived_key));
717 static void __ekey_init(struct encrypted_key_payload *epayload,
718 const char *format, const char *master_desc,
721 unsigned int format_len;
723 format_len = (!format) ? strlen(key_format_default) : strlen(format);
724 epayload->format = epayload->payload_data + epayload->payload_datalen;
725 epayload->master_desc = epayload->format + format_len + 1;
726 epayload->datalen = epayload->master_desc + strlen(master_desc) + 1;
727 epayload->iv = epayload->datalen + strlen(datalen) + 1;
728 epayload->encrypted_data = epayload->iv + ivsize + 1;
729 epayload->decrypted_data = epayload->payload_data;
732 memcpy(epayload->format, key_format_default, format_len);
734 if (!strcmp(format, key_format_ecryptfs))
735 epayload->decrypted_data =
736 ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data);
738 memcpy(epayload->format, format, format_len);
741 memcpy(epayload->master_desc, master_desc, strlen(master_desc));
742 memcpy(epayload->datalen, datalen, strlen(datalen));
746 * encrypted_init - initialize an encrypted key
748 * For a new key, use a random number for both the iv and data
749 * itself. For an old key, decrypt the hex encoded data.
751 static int encrypted_init(struct encrypted_key_payload *epayload,
752 const char *key_desc, const char *format,
753 const char *master_desc, const char *datalen,
754 const char *hex_encoded_iv)
758 if (format && !strcmp(format, key_format_ecryptfs)) {
759 ret = valid_ecryptfs_desc(key_desc);
763 ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data,
767 __ekey_init(epayload, format, master_desc, datalen);
768 if (!hex_encoded_iv) {
769 get_random_bytes(epayload->iv, ivsize);
771 get_random_bytes(epayload->decrypted_data,
772 epayload->decrypted_datalen);
774 ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv);
779 * encrypted_instantiate - instantiate an encrypted key
781 * Decrypt an existing encrypted datablob or create a new encrypted key
782 * based on a kernel random number.
784 * On success, return 0. Otherwise return errno.
786 static int encrypted_instantiate(struct key *key,
787 struct key_preparsed_payload *prep)
789 struct encrypted_key_payload *epayload = NULL;
790 char *datablob = NULL;
791 const char *format = NULL;
792 char *master_desc = NULL;
793 char *decrypted_datalen = NULL;
794 char *hex_encoded_iv = NULL;
795 size_t datalen = prep->datalen;
798 if (datalen <= 0 || datalen > 32767 || !prep->data)
801 datablob = kmalloc(datalen + 1, GFP_KERNEL);
804 datablob[datalen] = 0;
805 memcpy(datablob, prep->data, datalen);
806 ret = datablob_parse(datablob, &format, &master_desc,
807 &decrypted_datalen, &hex_encoded_iv);
811 epayload = encrypted_key_alloc(key, format, master_desc,
813 if (IS_ERR(epayload)) {
814 ret = PTR_ERR(epayload);
817 ret = encrypted_init(epayload, key->description, format, master_desc,
818 decrypted_datalen, hex_encoded_iv);
824 rcu_assign_keypointer(key, epayload);
830 static void encrypted_rcu_free(struct rcu_head *rcu)
832 struct encrypted_key_payload *epayload;
834 epayload = container_of(rcu, struct encrypted_key_payload, rcu);
839 * encrypted_update - update the master key description
841 * Change the master key description for an existing encrypted key.
842 * The next read will return an encrypted datablob using the new
843 * master key description.
845 * On success, return 0. Otherwise return errno.
847 static int encrypted_update(struct key *key, struct key_preparsed_payload *prep)
849 struct encrypted_key_payload *epayload = key->payload.data[0];
850 struct encrypted_key_payload *new_epayload;
852 char *new_master_desc = NULL;
853 const char *format = NULL;
854 size_t datalen = prep->datalen;
857 if (key_is_negative(key))
859 if (datalen <= 0 || datalen > 32767 || !prep->data)
862 buf = kmalloc(datalen + 1, GFP_KERNEL);
867 memcpy(buf, prep->data, datalen);
868 ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL);
872 ret = valid_master_desc(new_master_desc, epayload->master_desc);
876 new_epayload = encrypted_key_alloc(key, epayload->format,
877 new_master_desc, epayload->datalen);
878 if (IS_ERR(new_epayload)) {
879 ret = PTR_ERR(new_epayload);
883 __ekey_init(new_epayload, epayload->format, new_master_desc,
886 memcpy(new_epayload->iv, epayload->iv, ivsize);
887 memcpy(new_epayload->payload_data, epayload->payload_data,
888 epayload->payload_datalen);
890 rcu_assign_keypointer(key, new_epayload);
891 call_rcu(&epayload->rcu, encrypted_rcu_free);
898 * encrypted_read - format and copy out the encrypted data
900 * The resulting datablob format is:
901 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data>
903 * On success, return to userspace the encrypted key datablob size.
905 static long encrypted_read(const struct key *key, char *buffer,
908 struct encrypted_key_payload *epayload;
910 const u8 *master_key;
911 size_t master_keylen;
912 char derived_key[HASH_SIZE];
914 size_t asciiblob_len;
917 epayload = dereference_key_locked(key);
919 /* returns the hex encoded iv, encrypted-data, and hmac as ascii */
920 asciiblob_len = epayload->datablob_len + ivsize + 1
921 + roundup(epayload->decrypted_datalen, blksize)
924 if (!buffer || buflen < asciiblob_len)
925 return asciiblob_len;
927 mkey = request_master_key(epayload, &master_key, &master_keylen);
929 return PTR_ERR(mkey);
931 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
935 ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key);
939 ret = datablob_hmac_append(epayload, master_key, master_keylen);
943 ascii_buf = datablob_format(epayload, asciiblob_len);
951 memzero_explicit(derived_key, sizeof(derived_key));
953 memcpy(buffer, ascii_buf, asciiblob_len);
956 return asciiblob_len;
960 memzero_explicit(derived_key, sizeof(derived_key));
965 * encrypted_destroy - clear and free the key's payload
967 static void encrypted_destroy(struct key *key)
969 kzfree(key->payload.data[0]);
972 struct key_type key_type_encrypted = {
974 .instantiate = encrypted_instantiate,
975 .update = encrypted_update,
976 .destroy = encrypted_destroy,
977 .describe = user_describe,
978 .read = encrypted_read,
980 EXPORT_SYMBOL_GPL(key_type_encrypted);
982 static int __init init_encrypted(void)
986 hash_tfm = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC);
987 if (IS_ERR(hash_tfm)) {
988 pr_err("encrypted_key: can't allocate %s transform: %ld\n",
989 hash_alg, PTR_ERR(hash_tfm));
990 return PTR_ERR(hash_tfm);
993 ret = aes_get_sizes();
996 ret = register_key_type(&key_type_encrypted);
1001 crypto_free_shash(hash_tfm);
1006 static void __exit cleanup_encrypted(void)
1008 crypto_free_shash(hash_tfm);
1009 unregister_key_type(&key_type_encrypted);
1012 late_initcall(init_encrypted);
1013 module_exit(cleanup_encrypted);
1015 MODULE_LICENSE("GPL");