1 // SPDX-License-Identifier: GPL-2.0-only
3 * Copyright (C) 2010 IBM Corporation
4 * Copyright (C) 2010 Politecnico di Torino, Italy
5 * TORSEC group -- https://security.polito.it
8 * Mimi Zohar <zohar@us.ibm.com>
9 * Roberto Sassu <roberto.sassu@polito.it>
11 * See Documentation/security/keys/trusted-encrypted.rst
14 #include <linux/uaccess.h>
15 #include <linux/module.h>
16 #include <linux/init.h>
17 #include <linux/slab.h>
18 #include <linux/parser.h>
19 #include <linux/string.h>
20 #include <linux/err.h>
21 #include <keys/user-type.h>
22 #include <keys/trusted-type.h>
23 #include <keys/encrypted-type.h>
24 #include <linux/key-type.h>
25 #include <linux/random.h>
26 #include <linux/rcupdate.h>
27 #include <linux/scatterlist.h>
28 #include <linux/ctype.h>
29 #include <crypto/aes.h>
30 #include <crypto/algapi.h>
31 #include <crypto/hash.h>
32 #include <crypto/sha2.h>
33 #include <crypto/skcipher.h>
35 #include "encrypted.h"
36 #include "ecryptfs_format.h"
38 static const char KEY_TRUSTED_PREFIX[] = "trusted:";
39 static const char KEY_USER_PREFIX[] = "user:";
40 static const char hash_alg[] = "sha256";
41 static const char hmac_alg[] = "hmac(sha256)";
42 static const char blkcipher_alg[] = "cbc(aes)";
43 static const char key_format_default[] = "default";
44 static const char key_format_ecryptfs[] = "ecryptfs";
45 static const char key_format_enc32[] = "enc32";
46 static unsigned int ivsize;
49 #define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1)
50 #define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1)
51 #define KEY_ECRYPTFS_DESC_LEN 16
52 #define HASH_SIZE SHA256_DIGEST_SIZE
53 #define MAX_DATA_SIZE 4096
54 #define MIN_DATA_SIZE 20
55 #define KEY_ENC32_PAYLOAD_LEN 32
57 static struct crypto_shash *hash_tfm;
60 Opt_new, Opt_load, Opt_update, Opt_err
64 Opt_default, Opt_ecryptfs, Opt_enc32, Opt_error
67 static const match_table_t key_format_tokens = {
68 {Opt_default, "default"},
69 {Opt_ecryptfs, "ecryptfs"},
74 static const match_table_t key_tokens = {
77 {Opt_update, "update"},
81 static bool user_decrypted_data = IS_ENABLED(CONFIG_USER_DECRYPTED_DATA);
82 module_param(user_decrypted_data, bool, 0);
83 MODULE_PARM_DESC(user_decrypted_data,
84 "Allow instantiation of encrypted keys using provided decrypted data");
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> [<decrypted data>]
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, char **decrypted_data)
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) {
206 *master_desc = strsep(&datablob, " \t");
214 pr_info("encrypted_key: master key parameter is missing\n");
218 if (valid_master_desc(*master_desc, NULL) < 0) {
219 pr_info("encrypted_key: master key parameter \'%s\' "
220 "is invalid\n", *master_desc);
224 if (decrypted_datalen) {
225 *decrypted_datalen = strsep(&datablob, " \t");
226 if (!*decrypted_datalen) {
227 pr_info("encrypted_key: keylen parameter is missing\n");
234 if (!decrypted_datalen) {
235 pr_info("encrypted_key: keyword \'%s\' not allowed "
236 "when called from .update method\n", keyword);
239 *decrypted_data = strsep(&datablob, " \t");
240 if (!*decrypted_data) {
241 pr_info("encrypted_key: decrypted_data is missing\n");
247 if (!decrypted_datalen) {
248 pr_info("encrypted_key: keyword \'%s\' not allowed "
249 "when called from .update method\n", keyword);
252 *hex_encoded_iv = strsep(&datablob, " \t");
253 if (!*hex_encoded_iv) {
254 pr_info("encrypted_key: hex blob is missing\n");
260 if (decrypted_datalen) {
261 pr_info("encrypted_key: keyword \'%s\' not allowed "
262 "when called from .instantiate method\n",
269 pr_info("encrypted_key: keyword \'%s\' not recognized\n",
278 * datablob_format - format as an ascii string, before copying to userspace
280 static char *datablob_format(struct encrypted_key_payload *epayload,
281 size_t asciiblob_len)
283 char *ascii_buf, *bufp;
284 u8 *iv = epayload->iv;
288 ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL);
292 ascii_buf[asciiblob_len] = '\0';
294 /* copy datablob master_desc and datalen strings */
295 len = sprintf(ascii_buf, "%s %s %s ", epayload->format,
296 epayload->master_desc, epayload->datalen);
298 /* convert the hex encoded iv, encrypted-data and HMAC to ascii */
299 bufp = &ascii_buf[len];
300 for (i = 0; i < (asciiblob_len - len) / 2; i++)
301 bufp = hex_byte_pack(bufp, iv[i]);
307 * request_user_key - request the user key
309 * Use a user provided key to encrypt/decrypt an encrypted-key.
311 static struct key *request_user_key(const char *master_desc, const u8 **master_key,
312 size_t *master_keylen)
314 const struct user_key_payload *upayload;
317 ukey = request_key(&key_type_user, master_desc, NULL);
321 down_read(&ukey->sem);
322 upayload = user_key_payload_locked(ukey);
324 /* key was revoked before we acquired its semaphore */
327 ukey = ERR_PTR(-EKEYREVOKED);
330 *master_key = upayload->data;
331 *master_keylen = upayload->datalen;
336 static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen,
337 const u8 *buf, unsigned int buflen)
339 struct crypto_shash *tfm;
342 tfm = crypto_alloc_shash(hmac_alg, 0, 0);
344 pr_err("encrypted_key: can't alloc %s transform: %ld\n",
345 hmac_alg, PTR_ERR(tfm));
349 err = crypto_shash_setkey(tfm, key, keylen);
351 err = crypto_shash_tfm_digest(tfm, buf, buflen, digest);
352 crypto_free_shash(tfm);
356 enum derived_key_type { ENC_KEY, AUTH_KEY };
358 /* Derive authentication/encryption key from trusted key */
359 static int get_derived_key(u8 *derived_key, enum derived_key_type key_type,
360 const u8 *master_key, size_t master_keylen)
363 unsigned int derived_buf_len;
366 derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen;
367 if (derived_buf_len < HASH_SIZE)
368 derived_buf_len = HASH_SIZE;
370 derived_buf = kzalloc(derived_buf_len, GFP_KERNEL);
375 strcpy(derived_buf, "AUTH_KEY");
377 strcpy(derived_buf, "ENC_KEY");
379 memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
381 ret = crypto_shash_tfm_digest(hash_tfm, derived_buf, derived_buf_len,
383 kfree_sensitive(derived_buf);
387 static struct skcipher_request *init_skcipher_req(const u8 *key,
388 unsigned int key_len)
390 struct skcipher_request *req;
391 struct crypto_skcipher *tfm;
394 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
396 pr_err("encrypted_key: failed to load %s transform (%ld)\n",
397 blkcipher_alg, PTR_ERR(tfm));
398 return ERR_CAST(tfm);
401 ret = crypto_skcipher_setkey(tfm, key, key_len);
403 pr_err("encrypted_key: failed to setkey (%d)\n", ret);
404 crypto_free_skcipher(tfm);
408 req = skcipher_request_alloc(tfm, GFP_KERNEL);
410 pr_err("encrypted_key: failed to allocate request for %s\n",
412 crypto_free_skcipher(tfm);
413 return ERR_PTR(-ENOMEM);
416 skcipher_request_set_callback(req, 0, NULL, NULL);
420 static struct key *request_master_key(struct encrypted_key_payload *epayload,
421 const u8 **master_key, size_t *master_keylen)
423 struct key *mkey = ERR_PTR(-EINVAL);
425 if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX,
426 KEY_TRUSTED_PREFIX_LEN)) {
427 mkey = request_trusted_key(epayload->master_desc +
428 KEY_TRUSTED_PREFIX_LEN,
429 master_key, master_keylen);
430 } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX,
431 KEY_USER_PREFIX_LEN)) {
432 mkey = request_user_key(epayload->master_desc +
434 master_key, master_keylen);
439 int ret = PTR_ERR(mkey);
441 if (ret == -ENOTSUPP)
442 pr_info("encrypted_key: key %s not supported",
443 epayload->master_desc);
445 pr_info("encrypted_key: key %s not found",
446 epayload->master_desc);
450 dump_master_key(*master_key, *master_keylen);
455 /* Before returning data to userspace, encrypt decrypted data. */
456 static int derived_key_encrypt(struct encrypted_key_payload *epayload,
457 const u8 *derived_key,
458 unsigned int derived_keylen)
460 struct scatterlist sg_in[2];
461 struct scatterlist sg_out[1];
462 struct crypto_skcipher *tfm;
463 struct skcipher_request *req;
464 unsigned int encrypted_datalen;
465 u8 iv[AES_BLOCK_SIZE];
468 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
470 req = init_skcipher_req(derived_key, derived_keylen);
474 dump_decrypted_data(epayload);
476 sg_init_table(sg_in, 2);
477 sg_set_buf(&sg_in[0], epayload->decrypted_data,
478 epayload->decrypted_datalen);
479 sg_set_page(&sg_in[1], ZERO_PAGE(0), AES_BLOCK_SIZE, 0);
481 sg_init_table(sg_out, 1);
482 sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
484 memcpy(iv, epayload->iv, sizeof(iv));
485 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
486 ret = crypto_skcipher_encrypt(req);
487 tfm = crypto_skcipher_reqtfm(req);
488 skcipher_request_free(req);
489 crypto_free_skcipher(tfm);
491 pr_err("encrypted_key: failed to encrypt (%d)\n", ret);
493 dump_encrypted_data(epayload, encrypted_datalen);
498 static int datablob_hmac_append(struct encrypted_key_payload *epayload,
499 const u8 *master_key, size_t master_keylen)
501 u8 derived_key[HASH_SIZE];
505 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
509 digest = epayload->format + epayload->datablob_len;
510 ret = calc_hmac(digest, derived_key, sizeof derived_key,
511 epayload->format, epayload->datablob_len);
513 dump_hmac(NULL, digest, HASH_SIZE);
515 memzero_explicit(derived_key, sizeof(derived_key));
519 /* verify HMAC before decrypting encrypted key */
520 static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
521 const u8 *format, const u8 *master_key,
522 size_t master_keylen)
524 u8 derived_key[HASH_SIZE];
525 u8 digest[HASH_SIZE];
530 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
534 len = epayload->datablob_len;
536 p = epayload->master_desc;
537 len -= strlen(epayload->format) + 1;
539 p = epayload->format;
541 ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len);
544 ret = crypto_memneq(digest, epayload->format + epayload->datablob_len,
548 dump_hmac("datablob",
549 epayload->format + epayload->datablob_len,
551 dump_hmac("calc", digest, HASH_SIZE);
554 memzero_explicit(derived_key, sizeof(derived_key));
558 static int derived_key_decrypt(struct encrypted_key_payload *epayload,
559 const u8 *derived_key,
560 unsigned int derived_keylen)
562 struct scatterlist sg_in[1];
563 struct scatterlist sg_out[2];
564 struct crypto_skcipher *tfm;
565 struct skcipher_request *req;
566 unsigned int encrypted_datalen;
567 u8 iv[AES_BLOCK_SIZE];
571 /* Throwaway buffer to hold the unused zero padding at the end */
572 pad = kmalloc(AES_BLOCK_SIZE, GFP_KERNEL);
576 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
577 req = init_skcipher_req(derived_key, derived_keylen);
581 dump_encrypted_data(epayload, encrypted_datalen);
583 sg_init_table(sg_in, 1);
584 sg_init_table(sg_out, 2);
585 sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen);
586 sg_set_buf(&sg_out[0], epayload->decrypted_data,
587 epayload->decrypted_datalen);
588 sg_set_buf(&sg_out[1], pad, AES_BLOCK_SIZE);
590 memcpy(iv, epayload->iv, sizeof(iv));
591 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
592 ret = crypto_skcipher_decrypt(req);
593 tfm = crypto_skcipher_reqtfm(req);
594 skcipher_request_free(req);
595 crypto_free_skcipher(tfm);
598 dump_decrypted_data(epayload);
604 /* Allocate memory for decrypted key and datablob. */
605 static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
607 const char *master_desc,
609 const char *decrypted_data)
611 struct encrypted_key_payload *epayload = NULL;
612 unsigned short datablob_len;
613 unsigned short decrypted_datalen;
614 unsigned short payload_datalen;
615 unsigned int encrypted_datalen;
616 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;
629 if (decrypted_data) {
630 if (!user_decrypted_data) {
631 pr_err("encrypted key: instantiation of keys using provided decrypted data is disabled since CONFIG_USER_DECRYPTED_DATA is set to false\n");
632 return ERR_PTR(-EINVAL);
634 if (strlen(decrypted_data) != decrypted_datalen * 2) {
635 pr_err("encrypted key: decrypted data provided does not match decrypted data length provided\n");
636 return ERR_PTR(-EINVAL);
638 for (i = 0; i < strlen(decrypted_data); i++) {
639 if (!isxdigit(decrypted_data[i])) {
640 pr_err("encrypted key: decrypted data provided must contain only hexadecimal characters\n");
641 return ERR_PTR(-EINVAL);
647 if (!strcmp(format, key_format_ecryptfs)) {
648 if (dlen != ECRYPTFS_MAX_KEY_BYTES) {
649 pr_err("encrypted_key: keylen for the ecryptfs format must be equal to %d bytes\n",
650 ECRYPTFS_MAX_KEY_BYTES);
651 return ERR_PTR(-EINVAL);
653 decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES;
654 payload_datalen = sizeof(struct ecryptfs_auth_tok);
655 } else if (!strcmp(format, key_format_enc32)) {
656 if (decrypted_datalen != KEY_ENC32_PAYLOAD_LEN) {
657 pr_err("encrypted_key: enc32 key payload incorrect length: %d\n",
659 return ERR_PTR(-EINVAL);
664 encrypted_datalen = roundup(decrypted_datalen, blksize);
666 datablob_len = format_len + 1 + strlen(master_desc) + 1
667 + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen;
669 ret = key_payload_reserve(key, payload_datalen + datablob_len
674 epayload = kzalloc(sizeof(*epayload) + payload_datalen +
675 datablob_len + HASH_SIZE + 1, GFP_KERNEL);
677 return ERR_PTR(-ENOMEM);
679 epayload->payload_datalen = payload_datalen;
680 epayload->decrypted_datalen = decrypted_datalen;
681 epayload->datablob_len = datablob_len;
685 static int encrypted_key_decrypt(struct encrypted_key_payload *epayload,
686 const char *format, const char *hex_encoded_iv)
689 u8 derived_key[HASH_SIZE];
690 const u8 *master_key;
692 const char *hex_encoded_data;
693 unsigned int encrypted_datalen;
694 size_t master_keylen;
698 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
699 asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2;
700 if (strlen(hex_encoded_iv) != asciilen)
703 hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2;
704 ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize);
707 ret = hex2bin(epayload->encrypted_data, hex_encoded_data,
712 hmac = epayload->format + epayload->datablob_len;
713 ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2),
718 mkey = request_master_key(epayload, &master_key, &master_keylen);
720 return PTR_ERR(mkey);
722 ret = datablob_hmac_verify(epayload, format, master_key, master_keylen);
724 pr_err("encrypted_key: bad hmac (%d)\n", ret);
728 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
732 ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key);
734 pr_err("encrypted_key: failed to decrypt key (%d)\n", ret);
738 memzero_explicit(derived_key, sizeof(derived_key));
742 static void __ekey_init(struct encrypted_key_payload *epayload,
743 const char *format, const char *master_desc,
746 unsigned int format_len;
748 format_len = (!format) ? strlen(key_format_default) : strlen(format);
749 epayload->format = epayload->payload_data + epayload->payload_datalen;
750 epayload->master_desc = epayload->format + format_len + 1;
751 epayload->datalen = epayload->master_desc + strlen(master_desc) + 1;
752 epayload->iv = epayload->datalen + strlen(datalen) + 1;
753 epayload->encrypted_data = epayload->iv + ivsize + 1;
754 epayload->decrypted_data = epayload->payload_data;
757 memcpy(epayload->format, key_format_default, format_len);
759 if (!strcmp(format, key_format_ecryptfs))
760 epayload->decrypted_data =
761 ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data);
763 memcpy(epayload->format, format, format_len);
766 memcpy(epayload->master_desc, master_desc, strlen(master_desc));
767 memcpy(epayload->datalen, datalen, strlen(datalen));
771 * encrypted_init - initialize an encrypted key
773 * For a new key, use either a random number or user-provided decrypted data in
774 * case it is provided. A random number is used for the iv in both cases. For
775 * an old key, decrypt the hex encoded data.
777 static int encrypted_init(struct encrypted_key_payload *epayload,
778 const char *key_desc, const char *format,
779 const char *master_desc, const char *datalen,
780 const char *hex_encoded_iv, const char *decrypted_data)
784 if (format && !strcmp(format, key_format_ecryptfs)) {
785 ret = valid_ecryptfs_desc(key_desc);
789 ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data,
793 __ekey_init(epayload, format, master_desc, datalen);
794 if (hex_encoded_iv) {
795 ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv);
796 } else if (decrypted_data) {
797 get_random_bytes(epayload->iv, ivsize);
798 ret = hex2bin(epayload->decrypted_data, decrypted_data,
799 epayload->decrypted_datalen);
801 get_random_bytes(epayload->iv, ivsize);
802 get_random_bytes(epayload->decrypted_data, epayload->decrypted_datalen);
808 * encrypted_instantiate - instantiate an encrypted key
810 * Instantiates the key:
811 * - by decrypting an existing encrypted datablob, or
812 * - by creating a new encrypted key based on a kernel random number, or
813 * - using provided decrypted data.
815 * On success, return 0. Otherwise return errno.
817 static int encrypted_instantiate(struct key *key,
818 struct key_preparsed_payload *prep)
820 struct encrypted_key_payload *epayload = NULL;
821 char *datablob = NULL;
822 const char *format = NULL;
823 char *master_desc = NULL;
824 char *decrypted_datalen = NULL;
825 char *hex_encoded_iv = NULL;
826 char *decrypted_data = NULL;
827 size_t datalen = prep->datalen;
830 if (datalen <= 0 || datalen > 32767 || !prep->data)
833 datablob = kmalloc(datalen + 1, GFP_KERNEL);
836 datablob[datalen] = 0;
837 memcpy(datablob, prep->data, datalen);
838 ret = datablob_parse(datablob, &format, &master_desc,
839 &decrypted_datalen, &hex_encoded_iv, &decrypted_data);
843 epayload = encrypted_key_alloc(key, format, master_desc,
844 decrypted_datalen, decrypted_data);
845 if (IS_ERR(epayload)) {
846 ret = PTR_ERR(epayload);
849 ret = encrypted_init(epayload, key->description, format, master_desc,
850 decrypted_datalen, hex_encoded_iv, decrypted_data);
852 kfree_sensitive(epayload);
856 rcu_assign_keypointer(key, epayload);
858 kfree_sensitive(datablob);
862 static void encrypted_rcu_free(struct rcu_head *rcu)
864 struct encrypted_key_payload *epayload;
866 epayload = container_of(rcu, struct encrypted_key_payload, rcu);
867 kfree_sensitive(epayload);
871 * encrypted_update - update the master key description
873 * Change the master key description for an existing encrypted key.
874 * The next read will return an encrypted datablob using the new
875 * master key description.
877 * On success, return 0. Otherwise return errno.
879 static int encrypted_update(struct key *key, struct key_preparsed_payload *prep)
881 struct encrypted_key_payload *epayload = key->payload.data[0];
882 struct encrypted_key_payload *new_epayload;
884 char *new_master_desc = NULL;
885 const char *format = NULL;
886 size_t datalen = prep->datalen;
889 if (key_is_negative(key))
891 if (datalen <= 0 || datalen > 32767 || !prep->data)
894 buf = kmalloc(datalen + 1, GFP_KERNEL);
899 memcpy(buf, prep->data, datalen);
900 ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL, NULL);
904 ret = valid_master_desc(new_master_desc, epayload->master_desc);
908 new_epayload = encrypted_key_alloc(key, epayload->format,
909 new_master_desc, epayload->datalen, NULL);
910 if (IS_ERR(new_epayload)) {
911 ret = PTR_ERR(new_epayload);
915 __ekey_init(new_epayload, epayload->format, new_master_desc,
918 memcpy(new_epayload->iv, epayload->iv, ivsize);
919 memcpy(new_epayload->payload_data, epayload->payload_data,
920 epayload->payload_datalen);
922 rcu_assign_keypointer(key, new_epayload);
923 call_rcu(&epayload->rcu, encrypted_rcu_free);
925 kfree_sensitive(buf);
930 * encrypted_read - format and copy out the encrypted data
932 * The resulting datablob format is:
933 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data>
935 * On success, return to userspace the encrypted key datablob size.
937 static long encrypted_read(const struct key *key, char *buffer,
940 struct encrypted_key_payload *epayload;
942 const u8 *master_key;
943 size_t master_keylen;
944 char derived_key[HASH_SIZE];
946 size_t asciiblob_len;
949 epayload = dereference_key_locked(key);
951 /* returns the hex encoded iv, encrypted-data, and hmac as ascii */
952 asciiblob_len = epayload->datablob_len + ivsize + 1
953 + roundup(epayload->decrypted_datalen, blksize)
956 if (!buffer || buflen < asciiblob_len)
957 return asciiblob_len;
959 mkey = request_master_key(epayload, &master_key, &master_keylen);
961 return PTR_ERR(mkey);
963 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
967 ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key);
971 ret = datablob_hmac_append(epayload, master_key, master_keylen);
975 ascii_buf = datablob_format(epayload, asciiblob_len);
983 memzero_explicit(derived_key, sizeof(derived_key));
985 memcpy(buffer, ascii_buf, asciiblob_len);
986 kfree_sensitive(ascii_buf);
988 return asciiblob_len;
992 memzero_explicit(derived_key, sizeof(derived_key));
997 * encrypted_destroy - clear and free the key's payload
999 static void encrypted_destroy(struct key *key)
1001 kfree_sensitive(key->payload.data[0]);
1004 struct key_type key_type_encrypted = {
1005 .name = "encrypted",
1006 .instantiate = encrypted_instantiate,
1007 .update = encrypted_update,
1008 .destroy = encrypted_destroy,
1009 .describe = user_describe,
1010 .read = encrypted_read,
1012 EXPORT_SYMBOL_GPL(key_type_encrypted);
1014 static int __init init_encrypted(void)
1018 hash_tfm = crypto_alloc_shash(hash_alg, 0, 0);
1019 if (IS_ERR(hash_tfm)) {
1020 pr_err("encrypted_key: can't allocate %s transform: %ld\n",
1021 hash_alg, PTR_ERR(hash_tfm));
1022 return PTR_ERR(hash_tfm);
1025 ret = aes_get_sizes();
1028 ret = register_key_type(&key_type_encrypted);
1033 crypto_free_shash(hash_tfm);
1038 static void __exit cleanup_encrypted(void)
1040 crypto_free_shash(hash_tfm);
1041 unregister_key_type(&key_type_encrypted);
1044 late_initcall(init_encrypted);
1045 module_exit(cleanup_encrypted);
1047 MODULE_LICENSE("GPL");