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/sha.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 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) {
201 *master_desc = strsep(&datablob, " \t");
209 pr_info("encrypted_key: master key parameter is missing\n");
213 if (valid_master_desc(*master_desc, NULL) < 0) {
214 pr_info("encrypted_key: master key parameter \'%s\' "
215 "is invalid\n", *master_desc);
219 if (decrypted_datalen) {
220 *decrypted_datalen = strsep(&datablob, " \t");
221 if (!*decrypted_datalen) {
222 pr_info("encrypted_key: keylen parameter is missing\n");
229 if (!decrypted_datalen) {
230 pr_info("encrypted_key: keyword \'%s\' not allowed "
231 "when called from .update method\n", keyword);
237 if (!decrypted_datalen) {
238 pr_info("encrypted_key: keyword \'%s\' not allowed "
239 "when called from .update method\n", keyword);
242 *hex_encoded_iv = strsep(&datablob, " \t");
243 if (!*hex_encoded_iv) {
244 pr_info("encrypted_key: hex blob is missing\n");
250 if (decrypted_datalen) {
251 pr_info("encrypted_key: keyword \'%s\' not allowed "
252 "when called from .instantiate method\n",
259 pr_info("encrypted_key: keyword \'%s\' not recognized\n",
268 * datablob_format - format as an ascii string, before copying to userspace
270 static char *datablob_format(struct encrypted_key_payload *epayload,
271 size_t asciiblob_len)
273 char *ascii_buf, *bufp;
274 u8 *iv = epayload->iv;
278 ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL);
282 ascii_buf[asciiblob_len] = '\0';
284 /* copy datablob master_desc and datalen strings */
285 len = sprintf(ascii_buf, "%s %s %s ", epayload->format,
286 epayload->master_desc, epayload->datalen);
288 /* convert the hex encoded iv, encrypted-data and HMAC to ascii */
289 bufp = &ascii_buf[len];
290 for (i = 0; i < (asciiblob_len - len) / 2; i++)
291 bufp = hex_byte_pack(bufp, iv[i]);
297 * request_user_key - request the user key
299 * Use a user provided key to encrypt/decrypt an encrypted-key.
301 static struct key *request_user_key(const char *master_desc, const u8 **master_key,
302 size_t *master_keylen)
304 const struct user_key_payload *upayload;
307 ukey = request_key(&key_type_user, master_desc, NULL);
311 down_read(&ukey->sem);
312 upayload = user_key_payload_locked(ukey);
314 /* key was revoked before we acquired its semaphore */
317 ukey = ERR_PTR(-EKEYREVOKED);
320 *master_key = upayload->data;
321 *master_keylen = upayload->datalen;
326 static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen,
327 const u8 *buf, unsigned int buflen)
329 struct crypto_shash *tfm;
332 tfm = crypto_alloc_shash(hmac_alg, 0, 0);
334 pr_err("encrypted_key: can't alloc %s transform: %ld\n",
335 hmac_alg, PTR_ERR(tfm));
339 err = crypto_shash_setkey(tfm, key, keylen);
341 err = crypto_shash_tfm_digest(tfm, buf, buflen, digest);
342 crypto_free_shash(tfm);
346 enum derived_key_type { ENC_KEY, AUTH_KEY };
348 /* Derive authentication/encryption key from trusted key */
349 static int get_derived_key(u8 *derived_key, enum derived_key_type key_type,
350 const u8 *master_key, size_t master_keylen)
353 unsigned int derived_buf_len;
356 derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen;
357 if (derived_buf_len < HASH_SIZE)
358 derived_buf_len = HASH_SIZE;
360 derived_buf = kzalloc(derived_buf_len, GFP_KERNEL);
365 strcpy(derived_buf, "AUTH_KEY");
367 strcpy(derived_buf, "ENC_KEY");
369 memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
371 ret = crypto_shash_tfm_digest(hash_tfm, derived_buf, derived_buf_len,
373 kfree_sensitive(derived_buf);
377 static struct skcipher_request *init_skcipher_req(const u8 *key,
378 unsigned int key_len)
380 struct skcipher_request *req;
381 struct crypto_skcipher *tfm;
384 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
386 pr_err("encrypted_key: failed to load %s transform (%ld)\n",
387 blkcipher_alg, PTR_ERR(tfm));
388 return ERR_CAST(tfm);
391 ret = crypto_skcipher_setkey(tfm, key, key_len);
393 pr_err("encrypted_key: failed to setkey (%d)\n", ret);
394 crypto_free_skcipher(tfm);
398 req = skcipher_request_alloc(tfm, GFP_KERNEL);
400 pr_err("encrypted_key: failed to allocate request for %s\n",
402 crypto_free_skcipher(tfm);
403 return ERR_PTR(-ENOMEM);
406 skcipher_request_set_callback(req, 0, NULL, NULL);
410 static struct key *request_master_key(struct encrypted_key_payload *epayload,
411 const u8 **master_key, size_t *master_keylen)
413 struct key *mkey = ERR_PTR(-EINVAL);
415 if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX,
416 KEY_TRUSTED_PREFIX_LEN)) {
417 mkey = request_trusted_key(epayload->master_desc +
418 KEY_TRUSTED_PREFIX_LEN,
419 master_key, master_keylen);
420 } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX,
421 KEY_USER_PREFIX_LEN)) {
422 mkey = request_user_key(epayload->master_desc +
424 master_key, master_keylen);
429 int ret = PTR_ERR(mkey);
431 if (ret == -ENOTSUPP)
432 pr_info("encrypted_key: key %s not supported",
433 epayload->master_desc);
435 pr_info("encrypted_key: key %s not found",
436 epayload->master_desc);
440 dump_master_key(*master_key, *master_keylen);
445 /* Before returning data to userspace, encrypt decrypted data. */
446 static int derived_key_encrypt(struct encrypted_key_payload *epayload,
447 const u8 *derived_key,
448 unsigned int derived_keylen)
450 struct scatterlist sg_in[2];
451 struct scatterlist sg_out[1];
452 struct crypto_skcipher *tfm;
453 struct skcipher_request *req;
454 unsigned int encrypted_datalen;
455 u8 iv[AES_BLOCK_SIZE];
458 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
460 req = init_skcipher_req(derived_key, derived_keylen);
464 dump_decrypted_data(epayload);
466 sg_init_table(sg_in, 2);
467 sg_set_buf(&sg_in[0], epayload->decrypted_data,
468 epayload->decrypted_datalen);
469 sg_set_page(&sg_in[1], ZERO_PAGE(0), AES_BLOCK_SIZE, 0);
471 sg_init_table(sg_out, 1);
472 sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
474 memcpy(iv, epayload->iv, sizeof(iv));
475 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
476 ret = crypto_skcipher_encrypt(req);
477 tfm = crypto_skcipher_reqtfm(req);
478 skcipher_request_free(req);
479 crypto_free_skcipher(tfm);
481 pr_err("encrypted_key: failed to encrypt (%d)\n", ret);
483 dump_encrypted_data(epayload, encrypted_datalen);
488 static int datablob_hmac_append(struct encrypted_key_payload *epayload,
489 const u8 *master_key, size_t master_keylen)
491 u8 derived_key[HASH_SIZE];
495 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
499 digest = epayload->format + epayload->datablob_len;
500 ret = calc_hmac(digest, derived_key, sizeof derived_key,
501 epayload->format, epayload->datablob_len);
503 dump_hmac(NULL, digest, HASH_SIZE);
505 memzero_explicit(derived_key, sizeof(derived_key));
509 /* verify HMAC before decrypting encrypted key */
510 static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
511 const u8 *format, const u8 *master_key,
512 size_t master_keylen)
514 u8 derived_key[HASH_SIZE];
515 u8 digest[HASH_SIZE];
520 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
524 len = epayload->datablob_len;
526 p = epayload->master_desc;
527 len -= strlen(epayload->format) + 1;
529 p = epayload->format;
531 ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len);
534 ret = crypto_memneq(digest, epayload->format + epayload->datablob_len,
538 dump_hmac("datablob",
539 epayload->format + epayload->datablob_len,
541 dump_hmac("calc", digest, HASH_SIZE);
544 memzero_explicit(derived_key, sizeof(derived_key));
548 static int derived_key_decrypt(struct encrypted_key_payload *epayload,
549 const u8 *derived_key,
550 unsigned int derived_keylen)
552 struct scatterlist sg_in[1];
553 struct scatterlist sg_out[2];
554 struct crypto_skcipher *tfm;
555 struct skcipher_request *req;
556 unsigned int encrypted_datalen;
557 u8 iv[AES_BLOCK_SIZE];
561 /* Throwaway buffer to hold the unused zero padding at the end */
562 pad = kmalloc(AES_BLOCK_SIZE, GFP_KERNEL);
566 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
567 req = init_skcipher_req(derived_key, derived_keylen);
571 dump_encrypted_data(epayload, encrypted_datalen);
573 sg_init_table(sg_in, 1);
574 sg_init_table(sg_out, 2);
575 sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen);
576 sg_set_buf(&sg_out[0], epayload->decrypted_data,
577 epayload->decrypted_datalen);
578 sg_set_buf(&sg_out[1], pad, AES_BLOCK_SIZE);
580 memcpy(iv, epayload->iv, sizeof(iv));
581 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen, iv);
582 ret = crypto_skcipher_decrypt(req);
583 tfm = crypto_skcipher_reqtfm(req);
584 skcipher_request_free(req);
585 crypto_free_skcipher(tfm);
588 dump_decrypted_data(epayload);
594 /* Allocate memory for decrypted key and datablob. */
595 static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
597 const char *master_desc,
600 struct encrypted_key_payload *epayload = NULL;
601 unsigned short datablob_len;
602 unsigned short decrypted_datalen;
603 unsigned short payload_datalen;
604 unsigned int encrypted_datalen;
605 unsigned int format_len;
609 ret = kstrtol(datalen, 10, &dlen);
610 if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE)
611 return ERR_PTR(-EINVAL);
613 format_len = (!format) ? strlen(key_format_default) : strlen(format);
614 decrypted_datalen = dlen;
615 payload_datalen = decrypted_datalen;
617 if (!strcmp(format, key_format_ecryptfs)) {
618 if (dlen != ECRYPTFS_MAX_KEY_BYTES) {
619 pr_err("encrypted_key: keylen for the ecryptfs format must be equal to %d bytes\n",
620 ECRYPTFS_MAX_KEY_BYTES);
621 return ERR_PTR(-EINVAL);
623 decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES;
624 payload_datalen = sizeof(struct ecryptfs_auth_tok);
625 } else if (!strcmp(format, key_format_enc32)) {
626 if (decrypted_datalen != KEY_ENC32_PAYLOAD_LEN) {
627 pr_err("encrypted_key: enc32 key payload incorrect length: %d\n",
629 return ERR_PTR(-EINVAL);
634 encrypted_datalen = roundup(decrypted_datalen, blksize);
636 datablob_len = format_len + 1 + strlen(master_desc) + 1
637 + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen;
639 ret = key_payload_reserve(key, payload_datalen + datablob_len
644 epayload = kzalloc(sizeof(*epayload) + payload_datalen +
645 datablob_len + HASH_SIZE + 1, GFP_KERNEL);
647 return ERR_PTR(-ENOMEM);
649 epayload->payload_datalen = payload_datalen;
650 epayload->decrypted_datalen = decrypted_datalen;
651 epayload->datablob_len = datablob_len;
655 static int encrypted_key_decrypt(struct encrypted_key_payload *epayload,
656 const char *format, const char *hex_encoded_iv)
659 u8 derived_key[HASH_SIZE];
660 const u8 *master_key;
662 const char *hex_encoded_data;
663 unsigned int encrypted_datalen;
664 size_t master_keylen;
668 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
669 asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2;
670 if (strlen(hex_encoded_iv) != asciilen)
673 hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2;
674 ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize);
677 ret = hex2bin(epayload->encrypted_data, hex_encoded_data,
682 hmac = epayload->format + epayload->datablob_len;
683 ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2),
688 mkey = request_master_key(epayload, &master_key, &master_keylen);
690 return PTR_ERR(mkey);
692 ret = datablob_hmac_verify(epayload, format, master_key, master_keylen);
694 pr_err("encrypted_key: bad hmac (%d)\n", ret);
698 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
702 ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key);
704 pr_err("encrypted_key: failed to decrypt key (%d)\n", ret);
708 memzero_explicit(derived_key, sizeof(derived_key));
712 static void __ekey_init(struct encrypted_key_payload *epayload,
713 const char *format, const char *master_desc,
716 unsigned int format_len;
718 format_len = (!format) ? strlen(key_format_default) : strlen(format);
719 epayload->format = epayload->payload_data + epayload->payload_datalen;
720 epayload->master_desc = epayload->format + format_len + 1;
721 epayload->datalen = epayload->master_desc + strlen(master_desc) + 1;
722 epayload->iv = epayload->datalen + strlen(datalen) + 1;
723 epayload->encrypted_data = epayload->iv + ivsize + 1;
724 epayload->decrypted_data = epayload->payload_data;
727 memcpy(epayload->format, key_format_default, format_len);
729 if (!strcmp(format, key_format_ecryptfs))
730 epayload->decrypted_data =
731 ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data);
733 memcpy(epayload->format, format, format_len);
736 memcpy(epayload->master_desc, master_desc, strlen(master_desc));
737 memcpy(epayload->datalen, datalen, strlen(datalen));
741 * encrypted_init - initialize an encrypted key
743 * For a new key, use a random number for both the iv and data
744 * itself. For an old key, decrypt the hex encoded data.
746 static int encrypted_init(struct encrypted_key_payload *epayload,
747 const char *key_desc, const char *format,
748 const char *master_desc, const char *datalen,
749 const char *hex_encoded_iv)
753 if (format && !strcmp(format, key_format_ecryptfs)) {
754 ret = valid_ecryptfs_desc(key_desc);
758 ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data,
762 __ekey_init(epayload, format, master_desc, datalen);
763 if (!hex_encoded_iv) {
764 get_random_bytes(epayload->iv, ivsize);
766 get_random_bytes(epayload->decrypted_data,
767 epayload->decrypted_datalen);
769 ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv);
774 * encrypted_instantiate - instantiate an encrypted key
776 * Decrypt an existing encrypted datablob or create a new encrypted key
777 * based on a kernel random number.
779 * On success, return 0. Otherwise return errno.
781 static int encrypted_instantiate(struct key *key,
782 struct key_preparsed_payload *prep)
784 struct encrypted_key_payload *epayload = NULL;
785 char *datablob = NULL;
786 const char *format = NULL;
787 char *master_desc = NULL;
788 char *decrypted_datalen = NULL;
789 char *hex_encoded_iv = NULL;
790 size_t datalen = prep->datalen;
793 if (datalen <= 0 || datalen > 32767 || !prep->data)
796 datablob = kmalloc(datalen + 1, GFP_KERNEL);
799 datablob[datalen] = 0;
800 memcpy(datablob, prep->data, datalen);
801 ret = datablob_parse(datablob, &format, &master_desc,
802 &decrypted_datalen, &hex_encoded_iv);
806 epayload = encrypted_key_alloc(key, format, master_desc,
808 if (IS_ERR(epayload)) {
809 ret = PTR_ERR(epayload);
812 ret = encrypted_init(epayload, key->description, format, master_desc,
813 decrypted_datalen, hex_encoded_iv);
815 kfree_sensitive(epayload);
819 rcu_assign_keypointer(key, epayload);
821 kfree_sensitive(datablob);
825 static void encrypted_rcu_free(struct rcu_head *rcu)
827 struct encrypted_key_payload *epayload;
829 epayload = container_of(rcu, struct encrypted_key_payload, rcu);
830 kfree_sensitive(epayload);
834 * encrypted_update - update the master key description
836 * Change the master key description for an existing encrypted key.
837 * The next read will return an encrypted datablob using the new
838 * master key description.
840 * On success, return 0. Otherwise return errno.
842 static int encrypted_update(struct key *key, struct key_preparsed_payload *prep)
844 struct encrypted_key_payload *epayload = key->payload.data[0];
845 struct encrypted_key_payload *new_epayload;
847 char *new_master_desc = NULL;
848 const char *format = NULL;
849 size_t datalen = prep->datalen;
852 if (key_is_negative(key))
854 if (datalen <= 0 || datalen > 32767 || !prep->data)
857 buf = kmalloc(datalen + 1, GFP_KERNEL);
862 memcpy(buf, prep->data, datalen);
863 ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL);
867 ret = valid_master_desc(new_master_desc, epayload->master_desc);
871 new_epayload = encrypted_key_alloc(key, epayload->format,
872 new_master_desc, epayload->datalen);
873 if (IS_ERR(new_epayload)) {
874 ret = PTR_ERR(new_epayload);
878 __ekey_init(new_epayload, epayload->format, new_master_desc,
881 memcpy(new_epayload->iv, epayload->iv, ivsize);
882 memcpy(new_epayload->payload_data, epayload->payload_data,
883 epayload->payload_datalen);
885 rcu_assign_keypointer(key, new_epayload);
886 call_rcu(&epayload->rcu, encrypted_rcu_free);
888 kfree_sensitive(buf);
893 * encrypted_read - format and copy out the encrypted data
895 * The resulting datablob format is:
896 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data>
898 * On success, return to userspace the encrypted key datablob size.
900 static long encrypted_read(const struct key *key, char *buffer,
903 struct encrypted_key_payload *epayload;
905 const u8 *master_key;
906 size_t master_keylen;
907 char derived_key[HASH_SIZE];
909 size_t asciiblob_len;
912 epayload = dereference_key_locked(key);
914 /* returns the hex encoded iv, encrypted-data, and hmac as ascii */
915 asciiblob_len = epayload->datablob_len + ivsize + 1
916 + roundup(epayload->decrypted_datalen, blksize)
919 if (!buffer || buflen < asciiblob_len)
920 return asciiblob_len;
922 mkey = request_master_key(epayload, &master_key, &master_keylen);
924 return PTR_ERR(mkey);
926 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
930 ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key);
934 ret = datablob_hmac_append(epayload, master_key, master_keylen);
938 ascii_buf = datablob_format(epayload, asciiblob_len);
946 memzero_explicit(derived_key, sizeof(derived_key));
948 memcpy(buffer, ascii_buf, asciiblob_len);
949 kfree_sensitive(ascii_buf);
951 return asciiblob_len;
955 memzero_explicit(derived_key, sizeof(derived_key));
960 * encrypted_destroy - clear and free the key's payload
962 static void encrypted_destroy(struct key *key)
964 kfree_sensitive(key->payload.data[0]);
967 struct key_type key_type_encrypted = {
969 .instantiate = encrypted_instantiate,
970 .update = encrypted_update,
971 .destroy = encrypted_destroy,
972 .describe = user_describe,
973 .read = encrypted_read,
975 EXPORT_SYMBOL_GPL(key_type_encrypted);
977 static int __init init_encrypted(void)
981 hash_tfm = crypto_alloc_shash(hash_alg, 0, 0);
982 if (IS_ERR(hash_tfm)) {
983 pr_err("encrypted_key: can't allocate %s transform: %ld\n",
984 hash_alg, PTR_ERR(hash_tfm));
985 return PTR_ERR(hash_tfm);
988 ret = aes_get_sizes();
991 ret = register_key_type(&key_type_encrypted);
996 crypto_free_shash(hash_tfm);
1001 static void __exit cleanup_encrypted(void)
1003 crypto_free_shash(hash_tfm);
1004 unregister_key_type(&key_type_encrypted);
1007 late_initcall(init_encrypted);
1008 module_exit(cleanup_encrypted);
1010 MODULE_LICENSE("GPL");