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/hash.h>
31 #include <crypto/sha2.h>
32 #include <crypto/skcipher.h>
33 #include <crypto/utils.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");
243 if (!decrypted_datalen) {
244 pr_info("encrypted_key: keyword \'%s\' not allowed "
245 "when called from .update method\n", keyword);
248 *hex_encoded_iv = strsep(&datablob, " \t");
249 if (!*hex_encoded_iv) {
250 pr_info("encrypted_key: hex blob is missing\n");
256 if (decrypted_datalen) {
257 pr_info("encrypted_key: keyword \'%s\' not allowed "
258 "when called from .instantiate method\n",
265 pr_info("encrypted_key: keyword \'%s\' not recognized\n",
274 * datablob_format - format as an ascii string, before copying to userspace
276 static char *datablob_format(struct encrypted_key_payload *epayload,
277 size_t asciiblob_len)
279 char *ascii_buf, *bufp;
280 u8 *iv = epayload->iv;
284 ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL);
288 ascii_buf[asciiblob_len] = '\0';
290 /* copy datablob master_desc and datalen strings */
291 len = sprintf(ascii_buf, "%s %s %s ", epayload->format,
292 epayload->master_desc, epayload->datalen);
294 /* convert the hex encoded iv, encrypted-data and HMAC to ascii */
295 bufp = &ascii_buf[len];
296 for (i = 0; i < (asciiblob_len - len) / 2; i++)
297 bufp = hex_byte_pack(bufp, iv[i]);
303 * request_user_key - request the user key
305 * Use a user provided key to encrypt/decrypt an encrypted-key.
307 static struct key *request_user_key(const char *master_desc, const u8 **master_key,
308 size_t *master_keylen)
310 const struct user_key_payload *upayload;
313 ukey = request_key(&key_type_user, master_desc, NULL);
317 down_read(&ukey->sem);
318 upayload = user_key_payload_locked(ukey);
320 /* key was revoked before we acquired its semaphore */
323 ukey = ERR_PTR(-EKEYREVOKED);
326 *master_key = upayload->data;
327 *master_keylen = upayload->datalen;
332 static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen,
333 const u8 *buf, unsigned int buflen)
335 struct crypto_shash *tfm;
338 tfm = crypto_alloc_shash(hmac_alg, 0, 0);
340 pr_err("encrypted_key: can't alloc %s transform: %ld\n",
341 hmac_alg, PTR_ERR(tfm));
345 err = crypto_shash_setkey(tfm, key, keylen);
347 err = crypto_shash_tfm_digest(tfm, buf, buflen, digest);
348 crypto_free_shash(tfm);
352 enum derived_key_type { ENC_KEY, AUTH_KEY };
354 /* Derive authentication/encryption key from trusted key */
355 static int get_derived_key(u8 *derived_key, enum derived_key_type key_type,
356 const u8 *master_key, size_t master_keylen)
359 unsigned int derived_buf_len;
362 derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen;
363 if (derived_buf_len < HASH_SIZE)
364 derived_buf_len = HASH_SIZE;
366 derived_buf = kzalloc(derived_buf_len, GFP_KERNEL);
371 strcpy(derived_buf, "AUTH_KEY");
373 strcpy(derived_buf, "ENC_KEY");
375 memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
377 ret = crypto_shash_tfm_digest(hash_tfm, derived_buf, derived_buf_len,
379 kfree_sensitive(derived_buf);
383 static struct skcipher_request *init_skcipher_req(const u8 *key,
384 unsigned int key_len)
386 struct skcipher_request *req;
387 struct crypto_skcipher *tfm;
390 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
392 pr_err("encrypted_key: failed to load %s transform (%ld)\n",
393 blkcipher_alg, PTR_ERR(tfm));
394 return ERR_CAST(tfm);
397 ret = crypto_skcipher_setkey(tfm, key, key_len);
399 pr_err("encrypted_key: failed to setkey (%d)\n", ret);
400 crypto_free_skcipher(tfm);
404 req = skcipher_request_alloc(tfm, GFP_KERNEL);
406 pr_err("encrypted_key: failed to allocate request for %s\n",
408 crypto_free_skcipher(tfm);
409 return ERR_PTR(-ENOMEM);
412 skcipher_request_set_callback(req, 0, NULL, NULL);
416 static struct key *request_master_key(struct encrypted_key_payload *epayload,
417 const u8 **master_key, size_t *master_keylen)
419 struct key *mkey = ERR_PTR(-EINVAL);
421 if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX,
422 KEY_TRUSTED_PREFIX_LEN)) {
423 mkey = request_trusted_key(epayload->master_desc +
424 KEY_TRUSTED_PREFIX_LEN,
425 master_key, master_keylen);
426 } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX,
427 KEY_USER_PREFIX_LEN)) {
428 mkey = request_user_key(epayload->master_desc +
430 master_key, master_keylen);
435 int ret = PTR_ERR(mkey);
437 if (ret == -ENOTSUPP)
438 pr_info("encrypted_key: key %s not supported",
439 epayload->master_desc);
441 pr_info("encrypted_key: key %s not found",
442 epayload->master_desc);
446 dump_master_key(*master_key, *master_keylen);
451 /* Before returning data to userspace, encrypt decrypted data. */
452 static int derived_key_encrypt(struct encrypted_key_payload *epayload,
453 const u8 *derived_key,
454 unsigned int derived_keylen)
456 struct scatterlist sg_in[2];
457 struct scatterlist sg_out[1];
458 struct crypto_skcipher *tfm;
459 struct skcipher_request *req;
460 unsigned int encrypted_datalen;
461 u8 iv[AES_BLOCK_SIZE];
464 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
466 req = init_skcipher_req(derived_key, derived_keylen);
470 dump_decrypted_data(epayload);
472 sg_init_table(sg_in, 2);
473 sg_set_buf(&sg_in[0], epayload->decrypted_data,
474 epayload->decrypted_datalen);
475 sg_set_page(&sg_in[1], ZERO_PAGE(0), AES_BLOCK_SIZE, 0);
477 sg_init_table(sg_out, 1);
478 sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
480 memcpy(iv, epayload->iv, sizeof(iv));
481 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
482 ret = crypto_skcipher_encrypt(req);
483 tfm = crypto_skcipher_reqtfm(req);
484 skcipher_request_free(req);
485 crypto_free_skcipher(tfm);
487 pr_err("encrypted_key: failed to encrypt (%d)\n", ret);
489 dump_encrypted_data(epayload, encrypted_datalen);
494 static int datablob_hmac_append(struct encrypted_key_payload *epayload,
495 const u8 *master_key, size_t master_keylen)
497 u8 derived_key[HASH_SIZE];
501 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
505 digest = epayload->format + epayload->datablob_len;
506 ret = calc_hmac(digest, derived_key, sizeof derived_key,
507 epayload->format, epayload->datablob_len);
509 dump_hmac(NULL, digest, HASH_SIZE);
511 memzero_explicit(derived_key, sizeof(derived_key));
515 /* verify HMAC before decrypting encrypted key */
516 static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
517 const u8 *format, const u8 *master_key,
518 size_t master_keylen)
520 u8 derived_key[HASH_SIZE];
521 u8 digest[HASH_SIZE];
526 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
530 len = epayload->datablob_len;
532 p = epayload->master_desc;
533 len -= strlen(epayload->format) + 1;
535 p = epayload->format;
537 ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len);
540 ret = crypto_memneq(digest, epayload->format + epayload->datablob_len,
544 dump_hmac("datablob",
545 epayload->format + epayload->datablob_len,
547 dump_hmac("calc", digest, HASH_SIZE);
550 memzero_explicit(derived_key, sizeof(derived_key));
554 static int derived_key_decrypt(struct encrypted_key_payload *epayload,
555 const u8 *derived_key,
556 unsigned int derived_keylen)
558 struct scatterlist sg_in[1];
559 struct scatterlist sg_out[2];
560 struct crypto_skcipher *tfm;
561 struct skcipher_request *req;
562 unsigned int encrypted_datalen;
563 u8 iv[AES_BLOCK_SIZE];
567 /* Throwaway buffer to hold the unused zero padding at the end */
568 pad = kmalloc(AES_BLOCK_SIZE, GFP_KERNEL);
572 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
573 req = init_skcipher_req(derived_key, derived_keylen);
577 dump_encrypted_data(epayload, encrypted_datalen);
579 sg_init_table(sg_in, 1);
580 sg_init_table(sg_out, 2);
581 sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen);
582 sg_set_buf(&sg_out[0], epayload->decrypted_data,
583 epayload->decrypted_datalen);
584 sg_set_buf(&sg_out[1], pad, AES_BLOCK_SIZE);
586 memcpy(iv, epayload->iv, sizeof(iv));
587 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
588 ret = crypto_skcipher_decrypt(req);
589 tfm = crypto_skcipher_reqtfm(req);
590 skcipher_request_free(req);
591 crypto_free_skcipher(tfm);
594 dump_decrypted_data(epayload);
600 /* Allocate memory for decrypted key and datablob. */
601 static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
603 const char *master_desc,
605 const char *decrypted_data)
607 struct encrypted_key_payload *epayload = NULL;
608 unsigned short datablob_len;
609 unsigned short decrypted_datalen;
610 unsigned short payload_datalen;
611 unsigned int encrypted_datalen;
612 unsigned int format_len;
617 ret = kstrtol(datalen, 10, &dlen);
618 if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE)
619 return ERR_PTR(-EINVAL);
621 format_len = (!format) ? strlen(key_format_default) : strlen(format);
622 decrypted_datalen = dlen;
623 payload_datalen = decrypted_datalen;
625 if (decrypted_data) {
626 if (!user_decrypted_data) {
627 pr_err("encrypted key: instantiation of keys using provided decrypted data is disabled since CONFIG_USER_DECRYPTED_DATA is set to false\n");
628 return ERR_PTR(-EINVAL);
630 if (strlen(decrypted_data) != decrypted_datalen * 2) {
631 pr_err("encrypted key: decrypted data provided does not match decrypted data length provided\n");
632 return ERR_PTR(-EINVAL);
634 for (i = 0; i < strlen(decrypted_data); i++) {
635 if (!isxdigit(decrypted_data[i])) {
636 pr_err("encrypted key: decrypted data provided must contain only hexadecimal characters\n");
637 return ERR_PTR(-EINVAL);
643 if (!strcmp(format, key_format_ecryptfs)) {
644 if (dlen != ECRYPTFS_MAX_KEY_BYTES) {
645 pr_err("encrypted_key: keylen for the ecryptfs format must be equal to %d bytes\n",
646 ECRYPTFS_MAX_KEY_BYTES);
647 return ERR_PTR(-EINVAL);
649 decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES;
650 payload_datalen = sizeof(struct ecryptfs_auth_tok);
651 } else if (!strcmp(format, key_format_enc32)) {
652 if (decrypted_datalen != KEY_ENC32_PAYLOAD_LEN) {
653 pr_err("encrypted_key: enc32 key payload incorrect length: %d\n",
655 return ERR_PTR(-EINVAL);
660 encrypted_datalen = roundup(decrypted_datalen, blksize);
662 datablob_len = format_len + 1 + strlen(master_desc) + 1
663 + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen;
665 ret = key_payload_reserve(key, payload_datalen + datablob_len
670 epayload = kzalloc(sizeof(*epayload) + payload_datalen +
671 datablob_len + HASH_SIZE + 1, GFP_KERNEL);
673 return ERR_PTR(-ENOMEM);
675 epayload->payload_datalen = payload_datalen;
676 epayload->decrypted_datalen = decrypted_datalen;
677 epayload->datablob_len = datablob_len;
681 static int encrypted_key_decrypt(struct encrypted_key_payload *epayload,
682 const char *format, const char *hex_encoded_iv)
685 u8 derived_key[HASH_SIZE];
686 const u8 *master_key;
688 const char *hex_encoded_data;
689 unsigned int encrypted_datalen;
690 size_t master_keylen;
694 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
695 asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2;
696 if (strlen(hex_encoded_iv) != asciilen)
699 hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2;
700 ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize);
703 ret = hex2bin(epayload->encrypted_data, hex_encoded_data,
708 hmac = epayload->format + epayload->datablob_len;
709 ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2),
714 mkey = request_master_key(epayload, &master_key, &master_keylen);
716 return PTR_ERR(mkey);
718 ret = datablob_hmac_verify(epayload, format, master_key, master_keylen);
720 pr_err("encrypted_key: bad hmac (%d)\n", ret);
724 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
728 ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key);
730 pr_err("encrypted_key: failed to decrypt key (%d)\n", ret);
734 memzero_explicit(derived_key, sizeof(derived_key));
738 static void __ekey_init(struct encrypted_key_payload *epayload,
739 const char *format, const char *master_desc,
742 unsigned int format_len;
744 format_len = (!format) ? strlen(key_format_default) : strlen(format);
745 epayload->format = epayload->payload_data + epayload->payload_datalen;
746 epayload->master_desc = epayload->format + format_len + 1;
747 epayload->datalen = epayload->master_desc + strlen(master_desc) + 1;
748 epayload->iv = epayload->datalen + strlen(datalen) + 1;
749 epayload->encrypted_data = epayload->iv + ivsize + 1;
750 epayload->decrypted_data = epayload->payload_data;
753 memcpy(epayload->format, key_format_default, format_len);
755 if (!strcmp(format, key_format_ecryptfs))
756 epayload->decrypted_data =
757 ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data);
759 memcpy(epayload->format, format, format_len);
762 memcpy(epayload->master_desc, master_desc, strlen(master_desc));
763 memcpy(epayload->datalen, datalen, strlen(datalen));
767 * encrypted_init - initialize an encrypted key
769 * For a new key, use either a random number or user-provided decrypted data in
770 * case it is provided. A random number is used for the iv in both cases. For
771 * an old key, decrypt the hex encoded data.
773 static int encrypted_init(struct encrypted_key_payload *epayload,
774 const char *key_desc, const char *format,
775 const char *master_desc, const char *datalen,
776 const char *hex_encoded_iv, const char *decrypted_data)
780 if (format && !strcmp(format, key_format_ecryptfs)) {
781 ret = valid_ecryptfs_desc(key_desc);
785 ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data,
789 __ekey_init(epayload, format, master_desc, datalen);
790 if (hex_encoded_iv) {
791 ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv);
792 } else if (decrypted_data) {
793 get_random_bytes(epayload->iv, ivsize);
794 ret = hex2bin(epayload->decrypted_data, decrypted_data,
795 epayload->decrypted_datalen);
797 get_random_bytes(epayload->iv, ivsize);
798 get_random_bytes(epayload->decrypted_data, epayload->decrypted_datalen);
804 * encrypted_instantiate - instantiate an encrypted key
806 * Instantiates the key:
807 * - by decrypting an existing encrypted datablob, or
808 * - by creating a new encrypted key based on a kernel random number, or
809 * - using provided decrypted data.
811 * On success, return 0. Otherwise return errno.
813 static int encrypted_instantiate(struct key *key,
814 struct key_preparsed_payload *prep)
816 struct encrypted_key_payload *epayload = NULL;
817 char *datablob = NULL;
818 const char *format = NULL;
819 char *master_desc = NULL;
820 char *decrypted_datalen = NULL;
821 char *hex_encoded_iv = NULL;
822 char *decrypted_data = NULL;
823 size_t datalen = prep->datalen;
826 if (datalen <= 0 || datalen > 32767 || !prep->data)
829 datablob = kmalloc(datalen + 1, GFP_KERNEL);
832 datablob[datalen] = 0;
833 memcpy(datablob, prep->data, datalen);
834 ret = datablob_parse(datablob, &format, &master_desc,
835 &decrypted_datalen, &hex_encoded_iv, &decrypted_data);
839 epayload = encrypted_key_alloc(key, format, master_desc,
840 decrypted_datalen, decrypted_data);
841 if (IS_ERR(epayload)) {
842 ret = PTR_ERR(epayload);
845 ret = encrypted_init(epayload, key->description, format, master_desc,
846 decrypted_datalen, hex_encoded_iv, decrypted_data);
848 kfree_sensitive(epayload);
852 rcu_assign_keypointer(key, epayload);
854 kfree_sensitive(datablob);
858 static void encrypted_rcu_free(struct rcu_head *rcu)
860 struct encrypted_key_payload *epayload;
862 epayload = container_of(rcu, struct encrypted_key_payload, rcu);
863 kfree_sensitive(epayload);
867 * encrypted_update - update the master key description
869 * Change the master key description for an existing encrypted key.
870 * The next read will return an encrypted datablob using the new
871 * master key description.
873 * On success, return 0. Otherwise return errno.
875 static int encrypted_update(struct key *key, struct key_preparsed_payload *prep)
877 struct encrypted_key_payload *epayload = key->payload.data[0];
878 struct encrypted_key_payload *new_epayload;
880 char *new_master_desc = NULL;
881 const char *format = NULL;
882 size_t datalen = prep->datalen;
885 if (key_is_negative(key))
887 if (datalen <= 0 || datalen > 32767 || !prep->data)
890 buf = kmalloc(datalen + 1, GFP_KERNEL);
895 memcpy(buf, prep->data, datalen);
896 ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL, NULL);
900 ret = valid_master_desc(new_master_desc, epayload->master_desc);
904 new_epayload = encrypted_key_alloc(key, epayload->format,
905 new_master_desc, epayload->datalen, NULL);
906 if (IS_ERR(new_epayload)) {
907 ret = PTR_ERR(new_epayload);
911 __ekey_init(new_epayload, epayload->format, new_master_desc,
914 memcpy(new_epayload->iv, epayload->iv, ivsize);
915 memcpy(new_epayload->payload_data, epayload->payload_data,
916 epayload->payload_datalen);
918 rcu_assign_keypointer(key, new_epayload);
919 call_rcu(&epayload->rcu, encrypted_rcu_free);
921 kfree_sensitive(buf);
926 * encrypted_read - format and copy out the encrypted data
928 * The resulting datablob format is:
929 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data>
931 * On success, return to userspace the encrypted key datablob size.
933 static long encrypted_read(const struct key *key, char *buffer,
936 struct encrypted_key_payload *epayload;
938 const u8 *master_key;
939 size_t master_keylen;
940 char derived_key[HASH_SIZE];
942 size_t asciiblob_len;
945 epayload = dereference_key_locked(key);
947 /* returns the hex encoded iv, encrypted-data, and hmac as ascii */
948 asciiblob_len = epayload->datablob_len + ivsize + 1
949 + roundup(epayload->decrypted_datalen, blksize)
952 if (!buffer || buflen < asciiblob_len)
953 return asciiblob_len;
955 mkey = request_master_key(epayload, &master_key, &master_keylen);
957 return PTR_ERR(mkey);
959 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
963 ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key);
967 ret = datablob_hmac_append(epayload, master_key, master_keylen);
971 ascii_buf = datablob_format(epayload, asciiblob_len);
979 memzero_explicit(derived_key, sizeof(derived_key));
981 memcpy(buffer, ascii_buf, asciiblob_len);
982 kfree_sensitive(ascii_buf);
984 return asciiblob_len;
988 memzero_explicit(derived_key, sizeof(derived_key));
993 * encrypted_destroy - clear and free the key's payload
995 static void encrypted_destroy(struct key *key)
997 kfree_sensitive(key->payload.data[0]);
1000 struct key_type key_type_encrypted = {
1001 .name = "encrypted",
1002 .instantiate = encrypted_instantiate,
1003 .update = encrypted_update,
1004 .destroy = encrypted_destroy,
1005 .describe = user_describe,
1006 .read = encrypted_read,
1008 EXPORT_SYMBOL_GPL(key_type_encrypted);
1010 static int __init init_encrypted(void)
1014 hash_tfm = crypto_alloc_shash(hash_alg, 0, 0);
1015 if (IS_ERR(hash_tfm)) {
1016 pr_err("encrypted_key: can't allocate %s transform: %ld\n",
1017 hash_alg, PTR_ERR(hash_tfm));
1018 return PTR_ERR(hash_tfm);
1021 ret = aes_get_sizes();
1024 ret = register_key_type(&key_type_encrypted);
1029 crypto_free_shash(hash_tfm);
1034 static void __exit cleanup_encrypted(void)
1036 crypto_free_shash(hash_tfm);
1037 unregister_key_type(&key_type_encrypted);
1040 late_initcall(init_encrypted);
1041 module_exit(cleanup_encrypted);
1043 MODULE_LICENSE("GPL");