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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2010 IBM Corporation
4 * Copyright (C) 2010 Politecnico di Torino, Italy
5 * TORSEC group -- https://security.polito.it
6 *
7 * Authors:
8 * Mimi Zohar <zohar@us.ibm.com>
9 * Roberto Sassu <roberto.sassu@polito.it>
10 *
11 * See Documentation/security/keys/trusted-encrypted.rst
12 */
13
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>
34
35#include "encrypted.h"
36#include "ecryptfs_format.h"
37
38static const char KEY_TRUSTED_PREFIX[] = "trusted:";
39static const char KEY_USER_PREFIX[] = "user:";
40static const char hash_alg[] = "sha256";
41static const char hmac_alg[] = "hmac(sha256)";
42static const char blkcipher_alg[] = "cbc(aes)";
43static const char key_format_default[] = "default";
44static const char key_format_ecryptfs[] = "ecryptfs";
45static const char key_format_enc32[] = "enc32";
46static unsigned int ivsize;
47static int blksize;
48
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
56
57static struct crypto_shash *hash_tfm;
58
59enum {
60 Opt_new, Opt_load, Opt_update, Opt_err
61};
62
63enum {
64 Opt_default, Opt_ecryptfs, Opt_enc32, Opt_error
65};
66
67static const match_table_t key_format_tokens = {
68 {Opt_default, "default"},
69 {Opt_ecryptfs, "ecryptfs"},
70 {Opt_enc32, "enc32"},
71 {Opt_error, NULL}
72};
73
74static const match_table_t key_tokens = {
75 {Opt_new, "new"},
76 {Opt_load, "load"},
77 {Opt_update, "update"},
78 {Opt_err, NULL}
79};
80
81static int aes_get_sizes(void)
82{
83 struct crypto_skcipher *tfm;
84
85 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
86 if (IS_ERR(tfm)) {
87 pr_err("encrypted_key: failed to alloc_cipher (%ld)\n",
88 PTR_ERR(tfm));
89 return PTR_ERR(tfm);
90 }
91 ivsize = crypto_skcipher_ivsize(tfm);
92 blksize = crypto_skcipher_blocksize(tfm);
93 crypto_free_skcipher(tfm);
94 return 0;
95}
96
97/*
98 * valid_ecryptfs_desc - verify the description of a new/loaded encrypted key
99 *
100 * The description of a encrypted key with format 'ecryptfs' must contain
101 * exactly 16 hexadecimal characters.
102 *
103 */
104static int valid_ecryptfs_desc(const char *ecryptfs_desc)
105{
106 int i;
107
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);
111 return -EINVAL;
112 }
113
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");
118 return -EINVAL;
119 }
120 }
121
122 return 0;
123}
124
125/*
126 * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key
127 *
128 * key-type:= "trusted:" | "user:"
129 * desc:= master-key description
130 *
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.
134 *
135 * On success returns 0, otherwise -EINVAL.
136 */
137static int valid_master_desc(const char *new_desc, const char *orig_desc)
138{
139 int prefix_len;
140
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;
145 else
146 return -EINVAL;
147
148 if (!new_desc[prefix_len])
149 return -EINVAL;
150
151 if (orig_desc && strncmp(new_desc, orig_desc, prefix_len))
152 return -EINVAL;
153
154 return 0;
155}
156
157/*
158 * datablob_parse - parse the keyctl data
159 *
160 * datablob format:
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>
165 *
166 * Tokenizes a copy of the keyctl data, returning a pointer to each token,
167 * which is null terminated.
168 *
169 * On success returns 0, otherwise -EINVAL.
170 */
171static int datablob_parse(char *datablob, const char **format,
172 char **master_desc, char **decrypted_datalen,
173 char **hex_encoded_iv)
174{
175 substring_t args[MAX_OPT_ARGS];
176 int ret = -EINVAL;
177 int key_cmd;
178 int key_format;
179 char *p, *keyword;
180
181 keyword = strsep(&datablob, " \t");
182 if (!keyword) {
183 pr_info("encrypted_key: insufficient parameters specified\n");
184 return ret;
185 }
186 key_cmd = match_token(keyword, key_tokens, args);
187
188 /* Get optional format: default | ecryptfs */
189 p = strsep(&datablob, " \t");
190 if (!p) {
191 pr_err("encrypted_key: insufficient parameters specified\n");
192 return ret;
193 }
194
195 key_format = match_token(p, key_format_tokens, args);
196 switch (key_format) {
197 case Opt_ecryptfs:
198 case Opt_enc32:
199 case Opt_default:
200 *format = p;
201 *master_desc = strsep(&datablob, " \t");
202 break;
203 case Opt_error:
204 *master_desc = p;
205 break;
206 }
207
208 if (!*master_desc) {
209 pr_info("encrypted_key: master key parameter is missing\n");
210 goto out;
211 }
212
213 if (valid_master_desc(*master_desc, NULL) < 0) {
214 pr_info("encrypted_key: master key parameter \'%s\' "
215 "is invalid\n", *master_desc);
216 goto out;
217 }
218
219 if (decrypted_datalen) {
220 *decrypted_datalen = strsep(&datablob, " \t");
221 if (!*decrypted_datalen) {
222 pr_info("encrypted_key: keylen parameter is missing\n");
223 goto out;
224 }
225 }
226
227 switch (key_cmd) {
228 case Opt_new:
229 if (!decrypted_datalen) {
230 pr_info("encrypted_key: keyword \'%s\' not allowed "
231 "when called from .update method\n", keyword);
232 break;
233 }
234 ret = 0;
235 break;
236 case Opt_load:
237 if (!decrypted_datalen) {
238 pr_info("encrypted_key: keyword \'%s\' not allowed "
239 "when called from .update method\n", keyword);
240 break;
241 }
242 *hex_encoded_iv = strsep(&datablob, " \t");
243 if (!*hex_encoded_iv) {
244 pr_info("encrypted_key: hex blob is missing\n");
245 break;
246 }
247 ret = 0;
248 break;
249 case Opt_update:
250 if (decrypted_datalen) {
251 pr_info("encrypted_key: keyword \'%s\' not allowed "
252 "when called from .instantiate method\n",
253 keyword);
254 break;
255 }
256 ret = 0;
257 break;
258 case Opt_err:
259 pr_info("encrypted_key: keyword \'%s\' not recognized\n",
260 keyword);
261 break;
262 }
263out:
264 return ret;
265}
266
267/*
268 * datablob_format - format as an ascii string, before copying to userspace
269 */
270static char *datablob_format(struct encrypted_key_payload *epayload,
271 size_t asciiblob_len)
272{
273 char *ascii_buf, *bufp;
274 u8 *iv = epayload->iv;
275 int len;
276 int i;
277
278 ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL);
279 if (!ascii_buf)
280 goto out;
281
282 ascii_buf[asciiblob_len] = '\0';
283
284 /* copy datablob master_desc and datalen strings */
285 len = sprintf(ascii_buf, "%s %s %s ", epayload->format,
286 epayload->master_desc, epayload->datalen);
287
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]);
292out:
293 return ascii_buf;
294}
295
296/*
297 * request_user_key - request the user key
298 *
299 * Use a user provided key to encrypt/decrypt an encrypted-key.
300 */
301static struct key *request_user_key(const char *master_desc, const u8 **master_key,
302 size_t *master_keylen)
303{
304 const struct user_key_payload *upayload;
305 struct key *ukey;
306
307 ukey = request_key(&key_type_user, master_desc, NULL);
308 if (IS_ERR(ukey))
309 goto error;
310
311 down_read(&ukey->sem);
312 upayload = user_key_payload_locked(ukey);
313 if (!upayload) {
314 /* key was revoked before we acquired its semaphore */
315 up_read(&ukey->sem);
316 key_put(ukey);
317 ukey = ERR_PTR(-EKEYREVOKED);
318 goto error;
319 }
320 *master_key = upayload->data;
321 *master_keylen = upayload->datalen;
322error:
323 return ukey;
324}
325
326static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen,
327 const u8 *buf, unsigned int buflen)
328{
329 struct crypto_shash *tfm;
330 int err;
331
332 tfm = crypto_alloc_shash(hmac_alg, 0, 0);
333 if (IS_ERR(tfm)) {
334 pr_err("encrypted_key: can't alloc %s transform: %ld\n",
335 hmac_alg, PTR_ERR(tfm));
336 return PTR_ERR(tfm);
337 }
338
339 err = crypto_shash_setkey(tfm, key, keylen);
340 if (!err)
341 err = crypto_shash_tfm_digest(tfm, buf, buflen, digest);
342 crypto_free_shash(tfm);
343 return err;
344}
345
346enum derived_key_type { ENC_KEY, AUTH_KEY };
347
348/* Derive authentication/encryption key from trusted key */
349static int get_derived_key(u8 *derived_key, enum derived_key_type key_type,
350 const u8 *master_key, size_t master_keylen)
351{
352 u8 *derived_buf;
353 unsigned int derived_buf_len;
354 int ret;
355
356 derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen;
357 if (derived_buf_len < HASH_SIZE)
358 derived_buf_len = HASH_SIZE;
359
360 derived_buf = kzalloc(derived_buf_len, GFP_KERNEL);
361 if (!derived_buf)
362 return -ENOMEM;
363
364 if (key_type)
365 strcpy(derived_buf, "AUTH_KEY");
366 else
367 strcpy(derived_buf, "ENC_KEY");
368
369 memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
370 master_keylen);
371 ret = crypto_shash_tfm_digest(hash_tfm, derived_buf, derived_buf_len,
372 derived_key);
373 kfree_sensitive(derived_buf);
374 return ret;
375}
376
377static struct skcipher_request *init_skcipher_req(const u8 *key,
378 unsigned int key_len)
379{
380 struct skcipher_request *req;
381 struct crypto_skcipher *tfm;
382 int ret;
383
384 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
385 if (IS_ERR(tfm)) {
386 pr_err("encrypted_key: failed to load %s transform (%ld)\n",
387 blkcipher_alg, PTR_ERR(tfm));
388 return ERR_CAST(tfm);
389 }
390
391 ret = crypto_skcipher_setkey(tfm, key, key_len);
392 if (ret < 0) {
393 pr_err("encrypted_key: failed to setkey (%d)\n", ret);
394 crypto_free_skcipher(tfm);
395 return ERR_PTR(ret);
396 }
397
398 req = skcipher_request_alloc(tfm, GFP_KERNEL);
399 if (!req) {
400 pr_err("encrypted_key: failed to allocate request for %s\n",
401 blkcipher_alg);
402 crypto_free_skcipher(tfm);
403 return ERR_PTR(-ENOMEM);
404 }
405
406 skcipher_request_set_callback(req, 0, NULL, NULL);
407 return req;
408}
409
410static struct key *request_master_key(struct encrypted_key_payload *epayload,
411 const u8 **master_key, size_t *master_keylen)
412{
413 struct key *mkey = ERR_PTR(-EINVAL);
414
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 +
423 KEY_USER_PREFIX_LEN,
424 master_key, master_keylen);
425 } else
426 goto out;
427
428 if (IS_ERR(mkey)) {
429 int ret = PTR_ERR(mkey);
430
431 if (ret == -ENOTSUPP)
432 pr_info("encrypted_key: key %s not supported",
433 epayload->master_desc);
434 else
435 pr_info("encrypted_key: key %s not found",
436 epayload->master_desc);
437 goto out;
438 }
439
440 dump_master_key(*master_key, *master_keylen);
441out:
442 return mkey;
443}
444
445/* Before returning data to userspace, encrypt decrypted data. */
446static int derived_key_encrypt(struct encrypted_key_payload *epayload,
447 const u8 *derived_key,
448 unsigned int derived_keylen)
449{
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];
456 int ret;
457
458 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
459
460 req = init_skcipher_req(derived_key, derived_keylen);
461 ret = PTR_ERR(req);
462 if (IS_ERR(req))
463 goto out;
464 dump_decrypted_data(epayload);
465
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);
470
471 sg_init_table(sg_out, 1);
472 sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
473
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);
480 if (ret < 0)
481 pr_err("encrypted_key: failed to encrypt (%d)\n", ret);
482 else
483 dump_encrypted_data(epayload, encrypted_datalen);
484out:
485 return ret;
486}
487
488static int datablob_hmac_append(struct encrypted_key_payload *epayload,
489 const u8 *master_key, size_t master_keylen)
490{
491 u8 derived_key[HASH_SIZE];
492 u8 *digest;
493 int ret;
494
495 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
496 if (ret < 0)
497 goto out;
498
499 digest = epayload->format + epayload->datablob_len;
500 ret = calc_hmac(digest, derived_key, sizeof derived_key,
501 epayload->format, epayload->datablob_len);
502 if (!ret)
503 dump_hmac(NULL, digest, HASH_SIZE);
504out:
505 memzero_explicit(derived_key, sizeof(derived_key));
506 return ret;
507}
508
509/* verify HMAC before decrypting encrypted key */
510static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
511 const u8 *format, const u8 *master_key,
512 size_t master_keylen)
513{
514 u8 derived_key[HASH_SIZE];
515 u8 digest[HASH_SIZE];
516 int ret;
517 char *p;
518 unsigned short len;
519
520 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
521 if (ret < 0)
522 goto out;
523
524 len = epayload->datablob_len;
525 if (!format) {
526 p = epayload->master_desc;
527 len -= strlen(epayload->format) + 1;
528 } else
529 p = epayload->format;
530
531 ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len);
532 if (ret < 0)
533 goto out;
534 ret = crypto_memneq(digest, epayload->format + epayload->datablob_len,
535 sizeof(digest));
536 if (ret) {
537 ret = -EINVAL;
538 dump_hmac("datablob",
539 epayload->format + epayload->datablob_len,
540 HASH_SIZE);
541 dump_hmac("calc", digest, HASH_SIZE);
542 }
543out:
544 memzero_explicit(derived_key, sizeof(derived_key));
545 return ret;
546}
547
548static int derived_key_decrypt(struct encrypted_key_payload *epayload,
549 const u8 *derived_key,
550 unsigned int derived_keylen)
551{
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];
558 u8 *pad;
559 int ret;
560
561 /* Throwaway buffer to hold the unused zero padding at the end */
562 pad = kmalloc(AES_BLOCK_SIZE, GFP_KERNEL);
563 if (!pad)
564 return -ENOMEM;
565
566 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
567 req = init_skcipher_req(derived_key, derived_keylen);
568 ret = PTR_ERR(req);
569 if (IS_ERR(req))
570 goto out;
571 dump_encrypted_data(epayload, encrypted_datalen);
572
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);
579
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);
586 if (ret < 0)
587 goto out;
588 dump_decrypted_data(epayload);
589out:
590 kfree(pad);
591 return ret;
592}
593
594/* Allocate memory for decrypted key and datablob. */
595static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
596 const char *format,
597 const char *master_desc,
598 const char *datalen)
599{
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;
606 long dlen;
607 int ret;
608
609 ret = kstrtol(datalen, 10, &dlen);
610 if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE)
611 return ERR_PTR(-EINVAL);
612
613 format_len = (!format) ? strlen(key_format_default) : strlen(format);
614 decrypted_datalen = dlen;
615 payload_datalen = decrypted_datalen;
616 if (format) {
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);
622 }
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",
628 decrypted_datalen);
629 return ERR_PTR(-EINVAL);
630 }
631 }
632 }
633
634 encrypted_datalen = roundup(decrypted_datalen, blksize);
635
636 datablob_len = format_len + 1 + strlen(master_desc) + 1
637 + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen;
638
639 ret = key_payload_reserve(key, payload_datalen + datablob_len
640 + HASH_SIZE + 1);
641 if (ret < 0)
642 return ERR_PTR(ret);
643
644 epayload = kzalloc(sizeof(*epayload) + payload_datalen +
645 datablob_len + HASH_SIZE + 1, GFP_KERNEL);
646 if (!epayload)
647 return ERR_PTR(-ENOMEM);
648
649 epayload->payload_datalen = payload_datalen;
650 epayload->decrypted_datalen = decrypted_datalen;
651 epayload->datablob_len = datablob_len;
652 return epayload;
653}
654
655static int encrypted_key_decrypt(struct encrypted_key_payload *epayload,
656 const char *format, const char *hex_encoded_iv)
657{
658 struct key *mkey;
659 u8 derived_key[HASH_SIZE];
660 const u8 *master_key;
661 u8 *hmac;
662 const char *hex_encoded_data;
663 unsigned int encrypted_datalen;
664 size_t master_keylen;
665 size_t asciilen;
666 int ret;
667
668 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
669 asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2;
670 if (strlen(hex_encoded_iv) != asciilen)
671 return -EINVAL;
672
673 hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2;
674 ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize);
675 if (ret < 0)
676 return -EINVAL;
677 ret = hex2bin(epayload->encrypted_data, hex_encoded_data,
678 encrypted_datalen);
679 if (ret < 0)
680 return -EINVAL;
681
682 hmac = epayload->format + epayload->datablob_len;
683 ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2),
684 HASH_SIZE);
685 if (ret < 0)
686 return -EINVAL;
687
688 mkey = request_master_key(epayload, &master_key, &master_keylen);
689 if (IS_ERR(mkey))
690 return PTR_ERR(mkey);
691
692 ret = datablob_hmac_verify(epayload, format, master_key, master_keylen);
693 if (ret < 0) {
694 pr_err("encrypted_key: bad hmac (%d)\n", ret);
695 goto out;
696 }
697
698 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
699 if (ret < 0)
700 goto out;
701
702 ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key);
703 if (ret < 0)
704 pr_err("encrypted_key: failed to decrypt key (%d)\n", ret);
705out:
706 up_read(&mkey->sem);
707 key_put(mkey);
708 memzero_explicit(derived_key, sizeof(derived_key));
709 return ret;
710}
711
712static void __ekey_init(struct encrypted_key_payload *epayload,
713 const char *format, const char *master_desc,
714 const char *datalen)
715{
716 unsigned int format_len;
717
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;
725
726 if (!format)
727 memcpy(epayload->format, key_format_default, format_len);
728 else {
729 if (!strcmp(format, key_format_ecryptfs))
730 epayload->decrypted_data =
731 ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data);
732
733 memcpy(epayload->format, format, format_len);
734 }
735
736 memcpy(epayload->master_desc, master_desc, strlen(master_desc));
737 memcpy(epayload->datalen, datalen, strlen(datalen));
738}
739
740/*
741 * encrypted_init - initialize an encrypted key
742 *
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.
745 */
746static 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)
750{
751 int ret = 0;
752
753 if (format && !strcmp(format, key_format_ecryptfs)) {
754 ret = valid_ecryptfs_desc(key_desc);
755 if (ret < 0)
756 return ret;
757
758 ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data,
759 key_desc);
760 }
761
762 __ekey_init(epayload, format, master_desc, datalen);
763 if (!hex_encoded_iv) {
764 get_random_bytes(epayload->iv, ivsize);
765
766 get_random_bytes(epayload->decrypted_data,
767 epayload->decrypted_datalen);
768 } else
769 ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv);
770 return ret;
771}
772
773/*
774 * encrypted_instantiate - instantiate an encrypted key
775 *
776 * Decrypt an existing encrypted datablob or create a new encrypted key
777 * based on a kernel random number.
778 *
779 * On success, return 0. Otherwise return errno.
780 */
781static int encrypted_instantiate(struct key *key,
782 struct key_preparsed_payload *prep)
783{
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;
791 int ret;
792
793 if (datalen <= 0 || datalen > 32767 || !prep->data)
794 return -EINVAL;
795
796 datablob = kmalloc(datalen + 1, GFP_KERNEL);
797 if (!datablob)
798 return -ENOMEM;
799 datablob[datalen] = 0;
800 memcpy(datablob, prep->data, datalen);
801 ret = datablob_parse(datablob, &format, &master_desc,
802 &decrypted_datalen, &hex_encoded_iv);
803 if (ret < 0)
804 goto out;
805
806 epayload = encrypted_key_alloc(key, format, master_desc,
807 decrypted_datalen);
808 if (IS_ERR(epayload)) {
809 ret = PTR_ERR(epayload);
810 goto out;
811 }
812 ret = encrypted_init(epayload, key->description, format, master_desc,
813 decrypted_datalen, hex_encoded_iv);
814 if (ret < 0) {
815 kfree_sensitive(epayload);
816 goto out;
817 }
818
819 rcu_assign_keypointer(key, epayload);
820out:
821 kfree_sensitive(datablob);
822 return ret;
823}
824
825static void encrypted_rcu_free(struct rcu_head *rcu)
826{
827 struct encrypted_key_payload *epayload;
828
829 epayload = container_of(rcu, struct encrypted_key_payload, rcu);
830 kfree_sensitive(epayload);
831}
832
833/*
834 * encrypted_update - update the master key description
835 *
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.
839 *
840 * On success, return 0. Otherwise return errno.
841 */
842static int encrypted_update(struct key *key, struct key_preparsed_payload *prep)
843{
844 struct encrypted_key_payload *epayload = key->payload.data[0];
845 struct encrypted_key_payload *new_epayload;
846 char *buf;
847 char *new_master_desc = NULL;
848 const char *format = NULL;
849 size_t datalen = prep->datalen;
850 int ret = 0;
851
852 if (key_is_negative(key))
853 return -ENOKEY;
854 if (datalen <= 0 || datalen > 32767 || !prep->data)
855 return -EINVAL;
856
857 buf = kmalloc(datalen + 1, GFP_KERNEL);
858 if (!buf)
859 return -ENOMEM;
860
861 buf[datalen] = 0;
862 memcpy(buf, prep->data, datalen);
863 ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL);
864 if (ret < 0)
865 goto out;
866
867 ret = valid_master_desc(new_master_desc, epayload->master_desc);
868 if (ret < 0)
869 goto out;
870
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);
875 goto out;
876 }
877
878 __ekey_init(new_epayload, epayload->format, new_master_desc,
879 epayload->datalen);
880
881 memcpy(new_epayload->iv, epayload->iv, ivsize);
882 memcpy(new_epayload->payload_data, epayload->payload_data,
883 epayload->payload_datalen);
884
885 rcu_assign_keypointer(key, new_epayload);
886 call_rcu(&epayload->rcu, encrypted_rcu_free);
887out:
888 kfree_sensitive(buf);
889 return ret;
890}
891
892/*
893 * encrypted_read - format and copy out the encrypted data
894 *
895 * The resulting datablob format is:
896 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data>
897 *
898 * On success, return to userspace the encrypted key datablob size.
899 */
900static long encrypted_read(const struct key *key, char *buffer,
901 size_t buflen)
902{
903 struct encrypted_key_payload *epayload;
904 struct key *mkey;
905 const u8 *master_key;
906 size_t master_keylen;
907 char derived_key[HASH_SIZE];
908 char *ascii_buf;
909 size_t asciiblob_len;
910 int ret;
911
912 epayload = dereference_key_locked(key);
913
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)
917 + (HASH_SIZE * 2);
918
919 if (!buffer || buflen < asciiblob_len)
920 return asciiblob_len;
921
922 mkey = request_master_key(epayload, &master_key, &master_keylen);
923 if (IS_ERR(mkey))
924 return PTR_ERR(mkey);
925
926 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
927 if (ret < 0)
928 goto out;
929
930 ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key);
931 if (ret < 0)
932 goto out;
933
934 ret = datablob_hmac_append(epayload, master_key, master_keylen);
935 if (ret < 0)
936 goto out;
937
938 ascii_buf = datablob_format(epayload, asciiblob_len);
939 if (!ascii_buf) {
940 ret = -ENOMEM;
941 goto out;
942 }
943
944 up_read(&mkey->sem);
945 key_put(mkey);
946 memzero_explicit(derived_key, sizeof(derived_key));
947
948 memcpy(buffer, ascii_buf, asciiblob_len);
949 kfree_sensitive(ascii_buf);
950
951 return asciiblob_len;
952out:
953 up_read(&mkey->sem);
954 key_put(mkey);
955 memzero_explicit(derived_key, sizeof(derived_key));
956 return ret;
957}
958
959/*
960 * encrypted_destroy - clear and free the key's payload
961 */
962static void encrypted_destroy(struct key *key)
963{
964 kfree_sensitive(key->payload.data[0]);
965}
966
967struct key_type key_type_encrypted = {
968 .name = "encrypted",
969 .instantiate = encrypted_instantiate,
970 .update = encrypted_update,
971 .destroy = encrypted_destroy,
972 .describe = user_describe,
973 .read = encrypted_read,
974};
975EXPORT_SYMBOL_GPL(key_type_encrypted);
976
977static int __init init_encrypted(void)
978{
979 int ret;
980
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);
986 }
987
988 ret = aes_get_sizes();
989 if (ret < 0)
990 goto out;
991 ret = register_key_type(&key_type_encrypted);
992 if (ret < 0)
993 goto out;
994 return 0;
995out:
996 crypto_free_shash(hash_tfm);
997 return ret;
998
999}
1000
1001static void __exit cleanup_encrypted(void)
1002{
1003 crypto_free_shash(hash_tfm);
1004 unregister_key_type(&key_type_encrypted);
1005}
1006
1007late_initcall(init_encrypted);
1008module_exit(cleanup_encrypted);
1009
1010MODULE_LICENSE("GPL");
1/*
2 * Copyright (C) 2010 IBM Corporation
3 * Copyright (C) 2010 Politecnico di Torino, Italy
4 * TORSEC group -- http://security.polito.it
5 *
6 * Authors:
7 * Mimi Zohar <zohar@us.ibm.com>
8 * Roberto Sassu <roberto.sassu@polito.it>
9 *
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.
13 *
14 * See Documentation/security/keys-trusted-encrypted.txt
15 */
16
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/hash.h>
33#include <crypto/sha.h>
34#include <crypto/skcipher.h>
35
36#include "encrypted.h"
37#include "ecryptfs_format.h"
38
39static const char KEY_TRUSTED_PREFIX[] = "trusted:";
40static const char KEY_USER_PREFIX[] = "user:";
41static const char hash_alg[] = "sha256";
42static const char hmac_alg[] = "hmac(sha256)";
43static const char blkcipher_alg[] = "cbc(aes)";
44static const char key_format_default[] = "default";
45static const char key_format_ecryptfs[] = "ecryptfs";
46static unsigned int ivsize;
47static int blksize;
48
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
56struct sdesc {
57 struct shash_desc shash;
58 char ctx[];
59};
60
61static struct crypto_shash *hashalg;
62static struct crypto_shash *hmacalg;
63
64enum {
65 Opt_err = -1, Opt_new, Opt_load, Opt_update
66};
67
68enum {
69 Opt_error = -1, Opt_default, Opt_ecryptfs
70};
71
72static const match_table_t key_format_tokens = {
73 {Opt_default, "default"},
74 {Opt_ecryptfs, "ecryptfs"},
75 {Opt_error, NULL}
76};
77
78static const match_table_t key_tokens = {
79 {Opt_new, "new"},
80 {Opt_load, "load"},
81 {Opt_update, "update"},
82 {Opt_err, NULL}
83};
84
85static int aes_get_sizes(void)
86{
87 struct crypto_skcipher *tfm;
88
89 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
90 if (IS_ERR(tfm)) {
91 pr_err("encrypted_key: failed to alloc_cipher (%ld)\n",
92 PTR_ERR(tfm));
93 return PTR_ERR(tfm);
94 }
95 ivsize = crypto_skcipher_ivsize(tfm);
96 blksize = crypto_skcipher_blocksize(tfm);
97 crypto_free_skcipher(tfm);
98 return 0;
99}
100
101/*
102 * valid_ecryptfs_desc - verify the description of a new/loaded encrypted key
103 *
104 * The description of a encrypted key with format 'ecryptfs' must contain
105 * exactly 16 hexadecimal characters.
106 *
107 */
108static int valid_ecryptfs_desc(const char *ecryptfs_desc)
109{
110 int i;
111
112 if (strlen(ecryptfs_desc) != KEY_ECRYPTFS_DESC_LEN) {
113 pr_err("encrypted_key: key description must be %d hexadecimal "
114 "characters long\n", KEY_ECRYPTFS_DESC_LEN);
115 return -EINVAL;
116 }
117
118 for (i = 0; i < KEY_ECRYPTFS_DESC_LEN; i++) {
119 if (!isxdigit(ecryptfs_desc[i])) {
120 pr_err("encrypted_key: key description must contain "
121 "only hexadecimal characters\n");
122 return -EINVAL;
123 }
124 }
125
126 return 0;
127}
128
129/*
130 * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key
131 *
132 * key-type:= "trusted:" | "user:"
133 * desc:= master-key description
134 *
135 * Verify that 'key-type' is valid and that 'desc' exists. On key update,
136 * only the master key description is permitted to change, not the key-type.
137 * The key-type remains constant.
138 *
139 * On success returns 0, otherwise -EINVAL.
140 */
141static int valid_master_desc(const char *new_desc, const char *orig_desc)
142{
143 if (!memcmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) {
144 if (strlen(new_desc) == KEY_TRUSTED_PREFIX_LEN)
145 goto out;
146 if (orig_desc)
147 if (memcmp(new_desc, orig_desc, KEY_TRUSTED_PREFIX_LEN))
148 goto out;
149 } else if (!memcmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) {
150 if (strlen(new_desc) == KEY_USER_PREFIX_LEN)
151 goto out;
152 if (orig_desc)
153 if (memcmp(new_desc, orig_desc, KEY_USER_PREFIX_LEN))
154 goto out;
155 } else
156 goto out;
157 return 0;
158out:
159 return -EINVAL;
160}
161
162/*
163 * datablob_parse - parse the keyctl data
164 *
165 * datablob format:
166 * new [<format>] <master-key name> <decrypted data length>
167 * load [<format>] <master-key name> <decrypted data length>
168 * <encrypted iv + data>
169 * update <new-master-key name>
170 *
171 * Tokenizes a copy of the keyctl data, returning a pointer to each token,
172 * which is null terminated.
173 *
174 * On success returns 0, otherwise -EINVAL.
175 */
176static int datablob_parse(char *datablob, const char **format,
177 char **master_desc, char **decrypted_datalen,
178 char **hex_encoded_iv)
179{
180 substring_t args[MAX_OPT_ARGS];
181 int ret = -EINVAL;
182 int key_cmd;
183 int key_format;
184 char *p, *keyword;
185
186 keyword = strsep(&datablob, " \t");
187 if (!keyword) {
188 pr_info("encrypted_key: insufficient parameters specified\n");
189 return ret;
190 }
191 key_cmd = match_token(keyword, key_tokens, args);
192
193 /* Get optional format: default | ecryptfs */
194 p = strsep(&datablob, " \t");
195 if (!p) {
196 pr_err("encrypted_key: insufficient parameters specified\n");
197 return ret;
198 }
199
200 key_format = match_token(p, key_format_tokens, args);
201 switch (key_format) {
202 case Opt_ecryptfs:
203 case Opt_default:
204 *format = p;
205 *master_desc = strsep(&datablob, " \t");
206 break;
207 case Opt_error:
208 *master_desc = p;
209 break;
210 }
211
212 if (!*master_desc) {
213 pr_info("encrypted_key: master key parameter is missing\n");
214 goto out;
215 }
216
217 if (valid_master_desc(*master_desc, NULL) < 0) {
218 pr_info("encrypted_key: master key parameter \'%s\' "
219 "is invalid\n", *master_desc);
220 goto out;
221 }
222
223 if (decrypted_datalen) {
224 *decrypted_datalen = strsep(&datablob, " \t");
225 if (!*decrypted_datalen) {
226 pr_info("encrypted_key: keylen parameter is missing\n");
227 goto out;
228 }
229 }
230
231 switch (key_cmd) {
232 case Opt_new:
233 if (!decrypted_datalen) {
234 pr_info("encrypted_key: keyword \'%s\' not allowed "
235 "when called from .update method\n", keyword);
236 break;
237 }
238 ret = 0;
239 break;
240 case Opt_load:
241 if (!decrypted_datalen) {
242 pr_info("encrypted_key: keyword \'%s\' not allowed "
243 "when called from .update method\n", keyword);
244 break;
245 }
246 *hex_encoded_iv = strsep(&datablob, " \t");
247 if (!*hex_encoded_iv) {
248 pr_info("encrypted_key: hex blob is missing\n");
249 break;
250 }
251 ret = 0;
252 break;
253 case Opt_update:
254 if (decrypted_datalen) {
255 pr_info("encrypted_key: keyword \'%s\' not allowed "
256 "when called from .instantiate method\n",
257 keyword);
258 break;
259 }
260 ret = 0;
261 break;
262 case Opt_err:
263 pr_info("encrypted_key: keyword \'%s\' not recognized\n",
264 keyword);
265 break;
266 }
267out:
268 return ret;
269}
270
271/*
272 * datablob_format - format as an ascii string, before copying to userspace
273 */
274static char *datablob_format(struct encrypted_key_payload *epayload,
275 size_t asciiblob_len)
276{
277 char *ascii_buf, *bufp;
278 u8 *iv = epayload->iv;
279 int len;
280 int i;
281
282 ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL);
283 if (!ascii_buf)
284 goto out;
285
286 ascii_buf[asciiblob_len] = '\0';
287
288 /* copy datablob master_desc and datalen strings */
289 len = sprintf(ascii_buf, "%s %s %s ", epayload->format,
290 epayload->master_desc, epayload->datalen);
291
292 /* convert the hex encoded iv, encrypted-data and HMAC to ascii */
293 bufp = &ascii_buf[len];
294 for (i = 0; i < (asciiblob_len - len) / 2; i++)
295 bufp = hex_byte_pack(bufp, iv[i]);
296out:
297 return ascii_buf;
298}
299
300/*
301 * request_user_key - request the user key
302 *
303 * Use a user provided key to encrypt/decrypt an encrypted-key.
304 */
305static struct key *request_user_key(const char *master_desc, const u8 **master_key,
306 size_t *master_keylen)
307{
308 const struct user_key_payload *upayload;
309 struct key *ukey;
310
311 ukey = request_key(&key_type_user, master_desc, NULL);
312 if (IS_ERR(ukey))
313 goto error;
314
315 down_read(&ukey->sem);
316 upayload = user_key_payload(ukey);
317 *master_key = upayload->data;
318 *master_keylen = upayload->datalen;
319error:
320 return ukey;
321}
322
323static struct sdesc *alloc_sdesc(struct crypto_shash *alg)
324{
325 struct sdesc *sdesc;
326 int size;
327
328 size = sizeof(struct shash_desc) + crypto_shash_descsize(alg);
329 sdesc = kmalloc(size, GFP_KERNEL);
330 if (!sdesc)
331 return ERR_PTR(-ENOMEM);
332 sdesc->shash.tfm = alg;
333 sdesc->shash.flags = 0x0;
334 return sdesc;
335}
336
337static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen,
338 const u8 *buf, unsigned int buflen)
339{
340 struct sdesc *sdesc;
341 int ret;
342
343 sdesc = alloc_sdesc(hmacalg);
344 if (IS_ERR(sdesc)) {
345 pr_info("encrypted_key: can't alloc %s\n", hmac_alg);
346 return PTR_ERR(sdesc);
347 }
348
349 ret = crypto_shash_setkey(hmacalg, key, keylen);
350 if (!ret)
351 ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
352 kfree(sdesc);
353 return ret;
354}
355
356static int calc_hash(u8 *digest, const u8 *buf, unsigned int buflen)
357{
358 struct sdesc *sdesc;
359 int ret;
360
361 sdesc = alloc_sdesc(hashalg);
362 if (IS_ERR(sdesc)) {
363 pr_info("encrypted_key: can't alloc %s\n", hash_alg);
364 return PTR_ERR(sdesc);
365 }
366
367 ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest);
368 kfree(sdesc);
369 return ret;
370}
371
372enum derived_key_type { ENC_KEY, AUTH_KEY };
373
374/* Derive authentication/encryption key from trusted key */
375static int get_derived_key(u8 *derived_key, enum derived_key_type key_type,
376 const u8 *master_key, size_t master_keylen)
377{
378 u8 *derived_buf;
379 unsigned int derived_buf_len;
380 int ret;
381
382 derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen;
383 if (derived_buf_len < HASH_SIZE)
384 derived_buf_len = HASH_SIZE;
385
386 derived_buf = kzalloc(derived_buf_len, GFP_KERNEL);
387 if (!derived_buf) {
388 pr_err("encrypted_key: out of memory\n");
389 return -ENOMEM;
390 }
391 if (key_type)
392 strcpy(derived_buf, "AUTH_KEY");
393 else
394 strcpy(derived_buf, "ENC_KEY");
395
396 memcpy(derived_buf + strlen(derived_buf) + 1, master_key,
397 master_keylen);
398 ret = calc_hash(derived_key, derived_buf, derived_buf_len);
399 kfree(derived_buf);
400 return ret;
401}
402
403static struct skcipher_request *init_skcipher_req(const u8 *key,
404 unsigned int key_len)
405{
406 struct skcipher_request *req;
407 struct crypto_skcipher *tfm;
408 int ret;
409
410 tfm = crypto_alloc_skcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC);
411 if (IS_ERR(tfm)) {
412 pr_err("encrypted_key: failed to load %s transform (%ld)\n",
413 blkcipher_alg, PTR_ERR(tfm));
414 return ERR_CAST(tfm);
415 }
416
417 ret = crypto_skcipher_setkey(tfm, key, key_len);
418 if (ret < 0) {
419 pr_err("encrypted_key: failed to setkey (%d)\n", ret);
420 crypto_free_skcipher(tfm);
421 return ERR_PTR(ret);
422 }
423
424 req = skcipher_request_alloc(tfm, GFP_KERNEL);
425 if (!req) {
426 pr_err("encrypted_key: failed to allocate request for %s\n",
427 blkcipher_alg);
428 crypto_free_skcipher(tfm);
429 return ERR_PTR(-ENOMEM);
430 }
431
432 skcipher_request_set_callback(req, 0, NULL, NULL);
433 return req;
434}
435
436static struct key *request_master_key(struct encrypted_key_payload *epayload,
437 const u8 **master_key, size_t *master_keylen)
438{
439 struct key *mkey = NULL;
440
441 if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX,
442 KEY_TRUSTED_PREFIX_LEN)) {
443 mkey = request_trusted_key(epayload->master_desc +
444 KEY_TRUSTED_PREFIX_LEN,
445 master_key, master_keylen);
446 } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX,
447 KEY_USER_PREFIX_LEN)) {
448 mkey = request_user_key(epayload->master_desc +
449 KEY_USER_PREFIX_LEN,
450 master_key, master_keylen);
451 } else
452 goto out;
453
454 if (IS_ERR(mkey)) {
455 int ret = PTR_ERR(mkey);
456
457 if (ret == -ENOTSUPP)
458 pr_info("encrypted_key: key %s not supported",
459 epayload->master_desc);
460 else
461 pr_info("encrypted_key: key %s not found",
462 epayload->master_desc);
463 goto out;
464 }
465
466 dump_master_key(*master_key, *master_keylen);
467out:
468 return mkey;
469}
470
471/* Before returning data to userspace, encrypt decrypted data. */
472static int derived_key_encrypt(struct encrypted_key_payload *epayload,
473 const u8 *derived_key,
474 unsigned int derived_keylen)
475{
476 struct scatterlist sg_in[2];
477 struct scatterlist sg_out[1];
478 struct crypto_skcipher *tfm;
479 struct skcipher_request *req;
480 unsigned int encrypted_datalen;
481 unsigned int padlen;
482 char pad[16];
483 int ret;
484
485 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
486 padlen = encrypted_datalen - epayload->decrypted_datalen;
487
488 req = init_skcipher_req(derived_key, derived_keylen);
489 ret = PTR_ERR(req);
490 if (IS_ERR(req))
491 goto out;
492 dump_decrypted_data(epayload);
493
494 memset(pad, 0, sizeof pad);
495 sg_init_table(sg_in, 2);
496 sg_set_buf(&sg_in[0], epayload->decrypted_data,
497 epayload->decrypted_datalen);
498 sg_set_buf(&sg_in[1], pad, padlen);
499
500 sg_init_table(sg_out, 1);
501 sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen);
502
503 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen,
504 epayload->iv);
505 ret = crypto_skcipher_encrypt(req);
506 tfm = crypto_skcipher_reqtfm(req);
507 skcipher_request_free(req);
508 crypto_free_skcipher(tfm);
509 if (ret < 0)
510 pr_err("encrypted_key: failed to encrypt (%d)\n", ret);
511 else
512 dump_encrypted_data(epayload, encrypted_datalen);
513out:
514 return ret;
515}
516
517static int datablob_hmac_append(struct encrypted_key_payload *epayload,
518 const u8 *master_key, size_t master_keylen)
519{
520 u8 derived_key[HASH_SIZE];
521 u8 *digest;
522 int ret;
523
524 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
525 if (ret < 0)
526 goto out;
527
528 digest = epayload->format + epayload->datablob_len;
529 ret = calc_hmac(digest, derived_key, sizeof derived_key,
530 epayload->format, epayload->datablob_len);
531 if (!ret)
532 dump_hmac(NULL, digest, HASH_SIZE);
533out:
534 return ret;
535}
536
537/* verify HMAC before decrypting encrypted key */
538static int datablob_hmac_verify(struct encrypted_key_payload *epayload,
539 const u8 *format, const u8 *master_key,
540 size_t master_keylen)
541{
542 u8 derived_key[HASH_SIZE];
543 u8 digest[HASH_SIZE];
544 int ret;
545 char *p;
546 unsigned short len;
547
548 ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen);
549 if (ret < 0)
550 goto out;
551
552 len = epayload->datablob_len;
553 if (!format) {
554 p = epayload->master_desc;
555 len -= strlen(epayload->format) + 1;
556 } else
557 p = epayload->format;
558
559 ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len);
560 if (ret < 0)
561 goto out;
562 ret = memcmp(digest, epayload->format + epayload->datablob_len,
563 sizeof digest);
564 if (ret) {
565 ret = -EINVAL;
566 dump_hmac("datablob",
567 epayload->format + epayload->datablob_len,
568 HASH_SIZE);
569 dump_hmac("calc", digest, HASH_SIZE);
570 }
571out:
572 return ret;
573}
574
575static int derived_key_decrypt(struct encrypted_key_payload *epayload,
576 const u8 *derived_key,
577 unsigned int derived_keylen)
578{
579 struct scatterlist sg_in[1];
580 struct scatterlist sg_out[2];
581 struct crypto_skcipher *tfm;
582 struct skcipher_request *req;
583 unsigned int encrypted_datalen;
584 char pad[16];
585 int ret;
586
587 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
588 req = init_skcipher_req(derived_key, derived_keylen);
589 ret = PTR_ERR(req);
590 if (IS_ERR(req))
591 goto out;
592 dump_encrypted_data(epayload, encrypted_datalen);
593
594 memset(pad, 0, sizeof pad);
595 sg_init_table(sg_in, 1);
596 sg_init_table(sg_out, 2);
597 sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen);
598 sg_set_buf(&sg_out[0], epayload->decrypted_data,
599 epayload->decrypted_datalen);
600 sg_set_buf(&sg_out[1], pad, sizeof pad);
601
602 skcipher_request_set_crypt(req, sg_in, sg_out, encrypted_datalen,
603 epayload->iv);
604 ret = crypto_skcipher_decrypt(req);
605 tfm = crypto_skcipher_reqtfm(req);
606 skcipher_request_free(req);
607 crypto_free_skcipher(tfm);
608 if (ret < 0)
609 goto out;
610 dump_decrypted_data(epayload);
611out:
612 return ret;
613}
614
615/* Allocate memory for decrypted key and datablob. */
616static struct encrypted_key_payload *encrypted_key_alloc(struct key *key,
617 const char *format,
618 const char *master_desc,
619 const char *datalen)
620{
621 struct encrypted_key_payload *epayload = NULL;
622 unsigned short datablob_len;
623 unsigned short decrypted_datalen;
624 unsigned short payload_datalen;
625 unsigned int encrypted_datalen;
626 unsigned int format_len;
627 long dlen;
628 int ret;
629
630 ret = kstrtol(datalen, 10, &dlen);
631 if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE)
632 return ERR_PTR(-EINVAL);
633
634 format_len = (!format) ? strlen(key_format_default) : strlen(format);
635 decrypted_datalen = dlen;
636 payload_datalen = decrypted_datalen;
637 if (format && !strcmp(format, key_format_ecryptfs)) {
638 if (dlen != ECRYPTFS_MAX_KEY_BYTES) {
639 pr_err("encrypted_key: keylen for the ecryptfs format "
640 "must be equal to %d bytes\n",
641 ECRYPTFS_MAX_KEY_BYTES);
642 return ERR_PTR(-EINVAL);
643 }
644 decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES;
645 payload_datalen = sizeof(struct ecryptfs_auth_tok);
646 }
647
648 encrypted_datalen = roundup(decrypted_datalen, blksize);
649
650 datablob_len = format_len + 1 + strlen(master_desc) + 1
651 + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen;
652
653 ret = key_payload_reserve(key, payload_datalen + datablob_len
654 + HASH_SIZE + 1);
655 if (ret < 0)
656 return ERR_PTR(ret);
657
658 epayload = kzalloc(sizeof(*epayload) + payload_datalen +
659 datablob_len + HASH_SIZE + 1, GFP_KERNEL);
660 if (!epayload)
661 return ERR_PTR(-ENOMEM);
662
663 epayload->payload_datalen = payload_datalen;
664 epayload->decrypted_datalen = decrypted_datalen;
665 epayload->datablob_len = datablob_len;
666 return epayload;
667}
668
669static int encrypted_key_decrypt(struct encrypted_key_payload *epayload,
670 const char *format, const char *hex_encoded_iv)
671{
672 struct key *mkey;
673 u8 derived_key[HASH_SIZE];
674 const u8 *master_key;
675 u8 *hmac;
676 const char *hex_encoded_data;
677 unsigned int encrypted_datalen;
678 size_t master_keylen;
679 size_t asciilen;
680 int ret;
681
682 encrypted_datalen = roundup(epayload->decrypted_datalen, blksize);
683 asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2;
684 if (strlen(hex_encoded_iv) != asciilen)
685 return -EINVAL;
686
687 hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2;
688 ret = hex2bin(epayload->iv, hex_encoded_iv, ivsize);
689 if (ret < 0)
690 return -EINVAL;
691 ret = hex2bin(epayload->encrypted_data, hex_encoded_data,
692 encrypted_datalen);
693 if (ret < 0)
694 return -EINVAL;
695
696 hmac = epayload->format + epayload->datablob_len;
697 ret = hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2),
698 HASH_SIZE);
699 if (ret < 0)
700 return -EINVAL;
701
702 mkey = request_master_key(epayload, &master_key, &master_keylen);
703 if (IS_ERR(mkey))
704 return PTR_ERR(mkey);
705
706 ret = datablob_hmac_verify(epayload, format, master_key, master_keylen);
707 if (ret < 0) {
708 pr_err("encrypted_key: bad hmac (%d)\n", ret);
709 goto out;
710 }
711
712 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
713 if (ret < 0)
714 goto out;
715
716 ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key);
717 if (ret < 0)
718 pr_err("encrypted_key: failed to decrypt key (%d)\n", ret);
719out:
720 up_read(&mkey->sem);
721 key_put(mkey);
722 return ret;
723}
724
725static void __ekey_init(struct encrypted_key_payload *epayload,
726 const char *format, const char *master_desc,
727 const char *datalen)
728{
729 unsigned int format_len;
730
731 format_len = (!format) ? strlen(key_format_default) : strlen(format);
732 epayload->format = epayload->payload_data + epayload->payload_datalen;
733 epayload->master_desc = epayload->format + format_len + 1;
734 epayload->datalen = epayload->master_desc + strlen(master_desc) + 1;
735 epayload->iv = epayload->datalen + strlen(datalen) + 1;
736 epayload->encrypted_data = epayload->iv + ivsize + 1;
737 epayload->decrypted_data = epayload->payload_data;
738
739 if (!format)
740 memcpy(epayload->format, key_format_default, format_len);
741 else {
742 if (!strcmp(format, key_format_ecryptfs))
743 epayload->decrypted_data =
744 ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data);
745
746 memcpy(epayload->format, format, format_len);
747 }
748
749 memcpy(epayload->master_desc, master_desc, strlen(master_desc));
750 memcpy(epayload->datalen, datalen, strlen(datalen));
751}
752
753/*
754 * encrypted_init - initialize an encrypted key
755 *
756 * For a new key, use a random number for both the iv and data
757 * itself. For an old key, decrypt the hex encoded data.
758 */
759static int encrypted_init(struct encrypted_key_payload *epayload,
760 const char *key_desc, const char *format,
761 const char *master_desc, const char *datalen,
762 const char *hex_encoded_iv)
763{
764 int ret = 0;
765
766 if (format && !strcmp(format, key_format_ecryptfs)) {
767 ret = valid_ecryptfs_desc(key_desc);
768 if (ret < 0)
769 return ret;
770
771 ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data,
772 key_desc);
773 }
774
775 __ekey_init(epayload, format, master_desc, datalen);
776 if (!hex_encoded_iv) {
777 get_random_bytes(epayload->iv, ivsize);
778
779 get_random_bytes(epayload->decrypted_data,
780 epayload->decrypted_datalen);
781 } else
782 ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv);
783 return ret;
784}
785
786/*
787 * encrypted_instantiate - instantiate an encrypted key
788 *
789 * Decrypt an existing encrypted datablob or create a new encrypted key
790 * based on a kernel random number.
791 *
792 * On success, return 0. Otherwise return errno.
793 */
794static int encrypted_instantiate(struct key *key,
795 struct key_preparsed_payload *prep)
796{
797 struct encrypted_key_payload *epayload = NULL;
798 char *datablob = NULL;
799 const char *format = NULL;
800 char *master_desc = NULL;
801 char *decrypted_datalen = NULL;
802 char *hex_encoded_iv = NULL;
803 size_t datalen = prep->datalen;
804 int ret;
805
806 if (datalen <= 0 || datalen > 32767 || !prep->data)
807 return -EINVAL;
808
809 datablob = kmalloc(datalen + 1, GFP_KERNEL);
810 if (!datablob)
811 return -ENOMEM;
812 datablob[datalen] = 0;
813 memcpy(datablob, prep->data, datalen);
814 ret = datablob_parse(datablob, &format, &master_desc,
815 &decrypted_datalen, &hex_encoded_iv);
816 if (ret < 0)
817 goto out;
818
819 epayload = encrypted_key_alloc(key, format, master_desc,
820 decrypted_datalen);
821 if (IS_ERR(epayload)) {
822 ret = PTR_ERR(epayload);
823 goto out;
824 }
825 ret = encrypted_init(epayload, key->description, format, master_desc,
826 decrypted_datalen, hex_encoded_iv);
827 if (ret < 0) {
828 kfree(epayload);
829 goto out;
830 }
831
832 rcu_assign_keypointer(key, epayload);
833out:
834 kfree(datablob);
835 return ret;
836}
837
838static void encrypted_rcu_free(struct rcu_head *rcu)
839{
840 struct encrypted_key_payload *epayload;
841
842 epayload = container_of(rcu, struct encrypted_key_payload, rcu);
843 memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
844 kfree(epayload);
845}
846
847/*
848 * encrypted_update - update the master key description
849 *
850 * Change the master key description for an existing encrypted key.
851 * The next read will return an encrypted datablob using the new
852 * master key description.
853 *
854 * On success, return 0. Otherwise return errno.
855 */
856static int encrypted_update(struct key *key, struct key_preparsed_payload *prep)
857{
858 struct encrypted_key_payload *epayload = key->payload.data[0];
859 struct encrypted_key_payload *new_epayload;
860 char *buf;
861 char *new_master_desc = NULL;
862 const char *format = NULL;
863 size_t datalen = prep->datalen;
864 int ret = 0;
865
866 if (test_bit(KEY_FLAG_NEGATIVE, &key->flags))
867 return -ENOKEY;
868 if (datalen <= 0 || datalen > 32767 || !prep->data)
869 return -EINVAL;
870
871 buf = kmalloc(datalen + 1, GFP_KERNEL);
872 if (!buf)
873 return -ENOMEM;
874
875 buf[datalen] = 0;
876 memcpy(buf, prep->data, datalen);
877 ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL);
878 if (ret < 0)
879 goto out;
880
881 ret = valid_master_desc(new_master_desc, epayload->master_desc);
882 if (ret < 0)
883 goto out;
884
885 new_epayload = encrypted_key_alloc(key, epayload->format,
886 new_master_desc, epayload->datalen);
887 if (IS_ERR(new_epayload)) {
888 ret = PTR_ERR(new_epayload);
889 goto out;
890 }
891
892 __ekey_init(new_epayload, epayload->format, new_master_desc,
893 epayload->datalen);
894
895 memcpy(new_epayload->iv, epayload->iv, ivsize);
896 memcpy(new_epayload->payload_data, epayload->payload_data,
897 epayload->payload_datalen);
898
899 rcu_assign_keypointer(key, new_epayload);
900 call_rcu(&epayload->rcu, encrypted_rcu_free);
901out:
902 kfree(buf);
903 return ret;
904}
905
906/*
907 * encrypted_read - format and copy the encrypted data to userspace
908 *
909 * The resulting datablob format is:
910 * <master-key name> <decrypted data length> <encrypted iv> <encrypted data>
911 *
912 * On success, return to userspace the encrypted key datablob size.
913 */
914static long encrypted_read(const struct key *key, char __user *buffer,
915 size_t buflen)
916{
917 struct encrypted_key_payload *epayload;
918 struct key *mkey;
919 const u8 *master_key;
920 size_t master_keylen;
921 char derived_key[HASH_SIZE];
922 char *ascii_buf;
923 size_t asciiblob_len;
924 int ret;
925
926 epayload = rcu_dereference_key(key);
927
928 /* returns the hex encoded iv, encrypted-data, and hmac as ascii */
929 asciiblob_len = epayload->datablob_len + ivsize + 1
930 + roundup(epayload->decrypted_datalen, blksize)
931 + (HASH_SIZE * 2);
932
933 if (!buffer || buflen < asciiblob_len)
934 return asciiblob_len;
935
936 mkey = request_master_key(epayload, &master_key, &master_keylen);
937 if (IS_ERR(mkey))
938 return PTR_ERR(mkey);
939
940 ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen);
941 if (ret < 0)
942 goto out;
943
944 ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key);
945 if (ret < 0)
946 goto out;
947
948 ret = datablob_hmac_append(epayload, master_key, master_keylen);
949 if (ret < 0)
950 goto out;
951
952 ascii_buf = datablob_format(epayload, asciiblob_len);
953 if (!ascii_buf) {
954 ret = -ENOMEM;
955 goto out;
956 }
957
958 up_read(&mkey->sem);
959 key_put(mkey);
960
961 if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0)
962 ret = -EFAULT;
963 kfree(ascii_buf);
964
965 return asciiblob_len;
966out:
967 up_read(&mkey->sem);
968 key_put(mkey);
969 return ret;
970}
971
972/*
973 * encrypted_destroy - before freeing the key, clear the decrypted data
974 *
975 * Before freeing the key, clear the memory containing the decrypted
976 * key data.
977 */
978static void encrypted_destroy(struct key *key)
979{
980 struct encrypted_key_payload *epayload = key->payload.data[0];
981
982 if (!epayload)
983 return;
984
985 memset(epayload->decrypted_data, 0, epayload->decrypted_datalen);
986 kfree(key->payload.data[0]);
987}
988
989struct key_type key_type_encrypted = {
990 .name = "encrypted",
991 .instantiate = encrypted_instantiate,
992 .update = encrypted_update,
993 .destroy = encrypted_destroy,
994 .describe = user_describe,
995 .read = encrypted_read,
996};
997EXPORT_SYMBOL_GPL(key_type_encrypted);
998
999static void encrypted_shash_release(void)
1000{
1001 if (hashalg)
1002 crypto_free_shash(hashalg);
1003 if (hmacalg)
1004 crypto_free_shash(hmacalg);
1005}
1006
1007static int __init encrypted_shash_alloc(void)
1008{
1009 int ret;
1010
1011 hmacalg = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC);
1012 if (IS_ERR(hmacalg)) {
1013 pr_info("encrypted_key: could not allocate crypto %s\n",
1014 hmac_alg);
1015 return PTR_ERR(hmacalg);
1016 }
1017
1018 hashalg = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC);
1019 if (IS_ERR(hashalg)) {
1020 pr_info("encrypted_key: could not allocate crypto %s\n",
1021 hash_alg);
1022 ret = PTR_ERR(hashalg);
1023 goto hashalg_fail;
1024 }
1025
1026 return 0;
1027
1028hashalg_fail:
1029 crypto_free_shash(hmacalg);
1030 return ret;
1031}
1032
1033static int __init init_encrypted(void)
1034{
1035 int ret;
1036
1037 ret = encrypted_shash_alloc();
1038 if (ret < 0)
1039 return ret;
1040 ret = aes_get_sizes();
1041 if (ret < 0)
1042 goto out;
1043 ret = register_key_type(&key_type_encrypted);
1044 if (ret < 0)
1045 goto out;
1046 return 0;
1047out:
1048 encrypted_shash_release();
1049 return ret;
1050
1051}
1052
1053static void __exit cleanup_encrypted(void)
1054{
1055 encrypted_shash_release();
1056 unregister_key_type(&key_type_encrypted);
1057}
1058
1059late_initcall(init_encrypted);
1060module_exit(cleanup_encrypted);
1061
1062MODULE_LICENSE("GPL");