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 const char key_format_enc32[] = "enc32";
49 static unsigned int ivsize;
52 #define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1)
53 #define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1)
54 #define KEY_ECRYPTFS_DESC_LEN 16
55 #define HASH_SIZE SHA256_DIGEST_SIZE
56 #define MAX_DATA_SIZE 4096
57 #define MIN_DATA_SIZE 20
58 #define KEY_ENC32_PAYLOAD_LEN 32
60 static struct crypto_shash *hash_tfm;
63 Opt_err = -1, Opt_new, Opt_load, Opt_update
67 Opt_error = -1, Opt_default, Opt_ecryptfs, Opt_enc32
70 static const match_table_t key_format_tokens = {
71 {Opt_default, "default"},
72 {Opt_ecryptfs, "ecryptfs"},
77 static const match_table_t key_tokens = {
80 {Opt_update, "update"},
84 static int aes_get_sizes(void)
86 struct crypto_skcipher *tfm;
88 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
90 pr_err("encrypted_key: failed to alloc_cipher (%ld)\n",
94 ivsize = crypto_skcipher_ivsize(tfm);
95 blksize = crypto_skcipher_blocksize(tfm);
96 crypto_free_skcipher(tfm);
101 * valid_ecryptfs_desc - verify the description of a new/loaded encrypted key
103 * The description of a encrypted key with format 'ecryptfs' must contain
104 * exactly 16 hexadecimal characters.
107 static int valid_ecryptfs_desc(const char *ecryptfs_desc)
111 if (strlen(ecryptfs_desc) != KEY_ECRYPTFS_DESC_LEN) {
112 pr_err("encrypted_key: key description must be %d hexadecimal "
113 "characters long\n", KEY_ECRYPTFS_DESC_LEN);
117 for (i = 0; i < KEY_ECRYPTFS_DESC_LEN; i++) {
118 if (!isxdigit(ecryptfs_desc[i])) {
119 pr_err("encrypted_key: key description must contain "
120 "only hexadecimal characters\n");
129 * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key
131 * key-type:= "trusted:" | "user:"
132 * desc:= master-key description
134 * Verify that 'key-type' is valid and that 'desc' exists. On key update,
135 * only the master key description is permitted to change, not the key-type.
136 * The key-type remains constant.
138 * On success returns 0, otherwise -EINVAL.
140 static int valid_master_desc(const char *new_desc, const char *orig_desc)
144 if (!strncmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN))
145 prefix_len = KEY_TRUSTED_PREFIX_LEN;
146 else if (!strncmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN))
147 prefix_len = KEY_USER_PREFIX_LEN;
151 if (!new_desc[prefix_len])
154 if (orig_desc && strncmp(new_desc, orig_desc, prefix_len))
161 * datablob_parse - parse the keyctl data
164 * new [<format>] <master-key name> <decrypted data length>
165 * load [<format>] <master-key name> <decrypted data length>
166 * <encrypted iv + data>
167 * update <new-master-key name>
169 * Tokenizes a copy of the keyctl data, returning a pointer to each token,
170 * which is null terminated.
172 * On success returns 0, otherwise -EINVAL.
174 static int datablob_parse(char *datablob, const char **format,
175 char **master_desc, char **decrypted_datalen,
176 char **hex_encoded_iv)
178 substring_t args[MAX_OPT_ARGS];
184 keyword = strsep(&datablob, " \t");
186 pr_info("encrypted_key: insufficient parameters specified\n");
189 key_cmd = match_token(keyword, key_tokens, args);
191 /* Get optional format: default | ecryptfs */
192 p = strsep(&datablob, " \t");
194 pr_err("encrypted_key: insufficient parameters specified\n");
198 key_format = match_token(p, key_format_tokens, args);
199 switch (key_format) {
204 *master_desc = strsep(&datablob, " \t");
212 pr_info("encrypted_key: master key parameter is missing\n");
216 if (valid_master_desc(*master_desc, NULL) < 0) {
217 pr_info("encrypted_key: master key parameter \'%s\' "
218 "is invalid\n", *master_desc);
222 if (decrypted_datalen) {
223 *decrypted_datalen = strsep(&datablob, " \t");
224 if (!*decrypted_datalen) {
225 pr_info("encrypted_key: keylen parameter is missing\n");
232 if (!decrypted_datalen) {
233 pr_info("encrypted_key: keyword \'%s\' not allowed "
234 "when called from .update method\n", keyword);
240 if (!decrypted_datalen) {
241 pr_info("encrypted_key: keyword \'%s\' not allowed "
242 "when called from .update method\n", keyword);
245 *hex_encoded_iv = strsep(&datablob, " \t");
246 if (!*hex_encoded_iv) {
247 pr_info("encrypted_key: hex blob is missing\n");
253 if (decrypted_datalen) {
254 pr_info("encrypted_key: keyword \'%s\' not allowed "
255 "when called from .instantiate method\n",
262 pr_info("encrypted_key: keyword \'%s\' not recognized\n",
271 * datablob_format - format as an ascii string, before copying to userspace
273 static char *datablob_format(struct encrypted_key_payload *epayload,
274 size_t asciiblob_len)
276 char *ascii_buf, *bufp;
277 u8 *iv = epayload->iv;
281 ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL);
285 ascii_buf[asciiblob_len] = '\0';
287 /* copy datablob master_desc and datalen strings */
288 len = sprintf(ascii_buf, "%s %s %s ", epayload->format,
289 epayload->master_desc, epayload->datalen);
291 /* convert the hex encoded iv, encrypted-data and HMAC to ascii */
292 bufp = &ascii_buf[len];
293 for (i = 0; i < (asciiblob_len - len) / 2; i++)
294 bufp = hex_byte_pack(bufp, iv[i]);
300 * request_user_key - request the user key
302 * Use a user provided key to encrypt/decrypt an encrypted-key.
304 static struct key *request_user_key(const char *master_desc, const u8 **master_key,
305 size_t *master_keylen)
307 const struct user_key_payload *upayload;
310 ukey = request_key(&key_type_user, master_desc, NULL);
314 down_read(&ukey->sem);
315 upayload = user_key_payload_locked(ukey);
317 /* key was revoked before we acquired its semaphore */
320 ukey = ERR_PTR(-EKEYREVOKED);
323 *master_key = upayload->data;
324 *master_keylen = upayload->datalen;
329 static int calc_hash(struct crypto_shash *tfm, u8 *digest,
330 const u8 *buf, unsigned int buflen)
332 SHASH_DESC_ON_STACK(desc, tfm);
338 err = crypto_shash_digest(desc, buf, buflen, digest);
339 shash_desc_zero(desc);
343 static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen,
344 const u8 *buf, unsigned int buflen)
346 struct crypto_shash *tfm;
349 tfm = crypto_alloc_shash(hmac_alg, 0, 0);
351 pr_err("encrypted_key: can't alloc %s transform: %ld\n",
352 hmac_alg, PTR_ERR(tfm));
356 err = crypto_shash_setkey(tfm, key, keylen);
358 err = calc_hash(tfm, digest, buf, buflen);
359 crypto_free_shash(tfm);
363 enum derived_key_type { ENC_KEY, AUTH_KEY };
365 /* Derive authentication/encryption key from trusted key */
366 static int get_derived_key(u8 *derived_key, enum derived_key_type key_type,
367 const u8 *master_key, size_t master_keylen)
370 unsigned int derived_buf_len;
373 derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen;
374 if (derived_buf_len < HASH_SIZE)
375 derived_buf_len = HASH_SIZE;
377 derived_buf = kzalloc(derived_buf_len, GFP_KERNEL);
382 strcpy(derived_buf, "AUTH_KEY");
384 strcpy(derived_buf, "ENC_KEY");
386 memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
388 ret = calc_hash(hash_tfm, derived_key, derived_buf, derived_buf_len);
393 static struct skcipher_request *init_skcipher_req(const u8 *key,
394 unsigned int key_len)
396 struct skcipher_request *req;
397 struct crypto_skcipher *tfm;
400 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
402 pr_err("encrypted_key: failed to load %s transform (%ld)\n",
403 blkcipher_alg, PTR_ERR(tfm));
404 return ERR_CAST(tfm);
407 ret = crypto_skcipher_setkey(tfm, key, key_len);
409 pr_err("encrypted_key: failed to setkey (%d)\n", ret);
410 crypto_free_skcipher(tfm);
414 req = skcipher_request_alloc(tfm, GFP_KERNEL);
416 pr_err("encrypted_key: failed to allocate request for %s\n",
418 crypto_free_skcipher(tfm);
419 return ERR_PTR(-ENOMEM);
422 skcipher_request_set_callback(req, 0, NULL, NULL);
426 static struct key *request_master_key(struct encrypted_key_payload *epayload,
427 const u8 **master_key, size_t *master_keylen)
429 struct key *mkey = ERR_PTR(-EINVAL);
431 if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX,
432 KEY_TRUSTED_PREFIX_LEN)) {
433 mkey = request_trusted_key(epayload->master_desc +
434 KEY_TRUSTED_PREFIX_LEN,
435 master_key, master_keylen);
436 } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX,
437 KEY_USER_PREFIX_LEN)) {
438 mkey = request_user_key(epayload->master_desc +
440 master_key, master_keylen);
445 int ret = PTR_ERR(mkey);
447 if (ret == -ENOTSUPP)
448 pr_info("encrypted_key: key %s not supported",
449 epayload->master_desc);
451 pr_info("encrypted_key: key %s not found",
452 epayload->master_desc);
456 dump_master_key(*master_key, *master_keylen);
461 /* Before returning data to userspace, encrypt decrypted data. */
462 static int derived_key_encrypt(struct encrypted_key_payload *epayload,
463 const u8 *derived_key,
464 unsigned int derived_keylen)
466 struct scatterlist sg_in[2];
467 struct scatterlist sg_out[1];
468 struct crypto_skcipher *tfm;
469 struct skcipher_request *req;
470 unsigned int encrypted_datalen;
471 u8 iv[AES_BLOCK_SIZE];
474 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
476 req = init_skcipher_req(derived_key, derived_keylen);
480 dump_decrypted_data(epayload);
482 sg_init_table(sg_in, 2);
483 sg_set_buf(&sg_in[0], epayload->decrypted_data,
484 epayload->decrypted_datalen);
485 sg_set_page(&sg_in[1], ZERO_PAGE(0), AES_BLOCK_SIZE, 0);
487 sg_init_table(sg_out, 1);
488 sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
490 memcpy(iv, epayload->iv, sizeof(iv));
491 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
492 ret = crypto_skcipher_encrypt(req);
493 tfm = crypto_skcipher_reqtfm(req);
494 skcipher_request_free(req);
495 crypto_free_skcipher(tfm);
497 pr_err("encrypted_key: failed to encrypt (%d)\n", ret);
499 dump_encrypted_data(epayload, encrypted_datalen);
504 static int datablob_hmac_append(struct encrypted_key_payload *epayload,
505 const u8 *master_key, size_t master_keylen)
507 u8 derived_key[HASH_SIZE];
511 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
515 digest = epayload->format + epayload->datablob_len;
516 ret = calc_hmac(digest, derived_key, sizeof derived_key,
517 epayload->format, epayload->datablob_len);
519 dump_hmac(NULL, digest, HASH_SIZE);
521 memzero_explicit(derived_key, sizeof(derived_key));
525 /* verify HMAC before decrypting encrypted key */
526 static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
527 const u8 *format, const u8 *master_key,
528 size_t master_keylen)
530 u8 derived_key[HASH_SIZE];
531 u8 digest[HASH_SIZE];
536 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
540 len = epayload->datablob_len;
542 p = epayload->master_desc;
543 len -= strlen(epayload->format) + 1;
545 p = epayload->format;
547 ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len);
550 ret = crypto_memneq(digest, epayload->format + epayload->datablob_len,
554 dump_hmac("datablob",
555 epayload->format + epayload->datablob_len,
557 dump_hmac("calc", digest, HASH_SIZE);
560 memzero_explicit(derived_key, sizeof(derived_key));
564 static int derived_key_decrypt(struct encrypted_key_payload *epayload,
565 const u8 *derived_key,
566 unsigned int derived_keylen)
568 struct scatterlist sg_in[1];
569 struct scatterlist sg_out[2];
570 struct crypto_skcipher *tfm;
571 struct skcipher_request *req;
572 unsigned int encrypted_datalen;
573 u8 iv[AES_BLOCK_SIZE];
577 /* Throwaway buffer to hold the unused zero padding at the end */
578 pad = kmalloc(AES_BLOCK_SIZE, GFP_KERNEL);
582 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
583 req = init_skcipher_req(derived_key, derived_keylen);
587 dump_encrypted_data(epayload, encrypted_datalen);
589 sg_init_table(sg_in, 1);
590 sg_init_table(sg_out, 2);
591 sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen);
592 sg_set_buf(&sg_out[0], epayload->decrypted_data,
593 epayload->decrypted_datalen);
594 sg_set_buf(&sg_out[1], pad, AES_BLOCK_SIZE);
596 memcpy(iv, epayload->iv, sizeof(iv));
597 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
598 ret = crypto_skcipher_decrypt(req);
599 tfm = crypto_skcipher_reqtfm(req);
600 skcipher_request_free(req);
601 crypto_free_skcipher(tfm);
604 dump_decrypted_data(epayload);
610 /* Allocate memory for decrypted key and datablob. */
611 static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
613 const char *master_desc,
616 struct encrypted_key_payload *epayload = NULL;
617 unsigned short datablob_len;
618 unsigned short decrypted_datalen;
619 unsigned short payload_datalen;
620 unsigned int encrypted_datalen;
621 unsigned int format_len;
625 ret = kstrtol(datalen, 10, &dlen);
626 if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE)
627 return ERR_PTR(-EINVAL);
629 format_len = (!format) ? strlen(key_format_default) : strlen(format);
630 decrypted_datalen = dlen;
631 payload_datalen = decrypted_datalen;
633 if (!strcmp(format, key_format_ecryptfs)) {
634 if (dlen != ECRYPTFS_MAX_KEY_BYTES) {
635 pr_err("encrypted_key: keylen for the ecryptfs format must be equal to %d bytes\n",
636 ECRYPTFS_MAX_KEY_BYTES);
637 return ERR_PTR(-EINVAL);
639 decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES;
640 payload_datalen = sizeof(struct ecryptfs_auth_tok);
641 } else if (!strcmp(format, key_format_enc32)) {
642 if (decrypted_datalen != KEY_ENC32_PAYLOAD_LEN) {
643 pr_err("encrypted_key: enc32 key payload incorrect length: %d\n",
645 return ERR_PTR(-EINVAL);
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);
724 memzero_explicit(derived_key, sizeof(derived_key));
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);
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 (key_is_negative(key))
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);
962 memzero_explicit(derived_key, sizeof(derived_key));
964 if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0)
968 return asciiblob_len;
972 memzero_explicit(derived_key, sizeof(derived_key));
977 * encrypted_destroy - clear and free the key's payload
979 static void encrypted_destroy(struct key *key)
981 kzfree(key->payload.data[0]);
984 struct key_type key_type_encrypted = {
986 .instantiate = encrypted_instantiate,
987 .update = encrypted_update,
988 .destroy = encrypted_destroy,
989 .describe = user_describe,
990 .read = encrypted_read,
992 EXPORT_SYMBOL_GPL(key_type_encrypted);
994 static int __init init_encrypted(void)
998 hash_tfm = crypto_alloc_shash(hash_alg, 0, 0);
999 if (IS_ERR(hash_tfm)) {
1000 pr_err("encrypted_key: can't allocate %s transform: %ld\n",
1001 hash_alg, PTR_ERR(hash_tfm));
1002 return PTR_ERR(hash_tfm);
1005 ret = aes_get_sizes();
1008 ret = register_key_type(&key_type_encrypted);
1013 crypto_free_shash(hash_tfm);
1018 static void __exit cleanup_encrypted(void)
1020 crypto_free_shash(hash_tfm);
1021 unregister_key_type(&key_type_encrypted);
1024 late_initcall(init_encrypted);
1025 module_exit(cleanup_encrypted);
1027 MODULE_LICENSE("GPL");