Root/
1 | /* |
2 | * Copyright (C) 2010 IBM Corporation |
3 | * |
4 | * Author: |
5 | * Mimi Zohar <zohar@us.ibm.com> |
6 | * |
7 | * This program is free software; you can redistribute it and/or modify |
8 | * it under the terms of the GNU General Public License as published by |
9 | * the Free Software Foundation, version 2 of the License. |
10 | * |
11 | * See Documentation/keys-trusted-encrypted.txt |
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/crypto.h> |
29 | #include <crypto/hash.h> |
30 | #include <crypto/sha.h> |
31 | #include <crypto/aes.h> |
32 | |
33 | #include "encrypted.h" |
34 | |
35 | static const char KEY_TRUSTED_PREFIX[] = "trusted:"; |
36 | static const char KEY_USER_PREFIX[] = "user:"; |
37 | static const char hash_alg[] = "sha256"; |
38 | static const char hmac_alg[] = "hmac(sha256)"; |
39 | static const char blkcipher_alg[] = "cbc(aes)"; |
40 | static unsigned int ivsize; |
41 | static int blksize; |
42 | |
43 | #define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1) |
44 | #define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1) |
45 | #define HASH_SIZE SHA256_DIGEST_SIZE |
46 | #define MAX_DATA_SIZE 4096 |
47 | #define MIN_DATA_SIZE 20 |
48 | |
49 | struct sdesc { |
50 | struct shash_desc shash; |
51 | char ctx[]; |
52 | }; |
53 | |
54 | static struct crypto_shash *hashalg; |
55 | static struct crypto_shash *hmacalg; |
56 | |
57 | enum { |
58 | Opt_err = -1, Opt_new, Opt_load, Opt_update |
59 | }; |
60 | |
61 | static const match_table_t key_tokens = { |
62 | {Opt_new, "new"}, |
63 | {Opt_load, "load"}, |
64 | {Opt_update, "update"}, |
65 | {Opt_err, NULL} |
66 | }; |
67 | |
68 | static int aes_get_sizes(void) |
69 | { |
70 | struct crypto_blkcipher *tfm; |
71 | |
72 | tfm = crypto_alloc_blkcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); |
73 | if (IS_ERR(tfm)) { |
74 | pr_err("encrypted_key: failed to alloc_cipher (%ld)\n", |
75 | PTR_ERR(tfm)); |
76 | return PTR_ERR(tfm); |
77 | } |
78 | ivsize = crypto_blkcipher_ivsize(tfm); |
79 | blksize = crypto_blkcipher_blocksize(tfm); |
80 | crypto_free_blkcipher(tfm); |
81 | return 0; |
82 | } |
83 | |
84 | /* |
85 | * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key |
86 | * |
87 | * key-type:= "trusted:" | "encrypted:" |
88 | * desc:= master-key description |
89 | * |
90 | * Verify that 'key-type' is valid and that 'desc' exists. On key update, |
91 | * only the master key description is permitted to change, not the key-type. |
92 | * The key-type remains constant. |
93 | * |
94 | * On success returns 0, otherwise -EINVAL. |
95 | */ |
96 | static int valid_master_desc(const char *new_desc, const char *orig_desc) |
97 | { |
98 | if (!memcmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) { |
99 | if (strlen(new_desc) == KEY_TRUSTED_PREFIX_LEN) |
100 | goto out; |
101 | if (orig_desc) |
102 | if (memcmp(new_desc, orig_desc, KEY_TRUSTED_PREFIX_LEN)) |
103 | goto out; |
104 | } else if (!memcmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) { |
105 | if (strlen(new_desc) == KEY_USER_PREFIX_LEN) |
106 | goto out; |
107 | if (orig_desc) |
108 | if (memcmp(new_desc, orig_desc, KEY_USER_PREFIX_LEN)) |
109 | goto out; |
110 | } else |
111 | goto out; |
112 | return 0; |
113 | out: |
114 | return -EINVAL; |
115 | } |
116 | |
117 | /* |
118 | * datablob_parse - parse the keyctl data |
119 | * |
120 | * datablob format: |
121 | * new <master-key name> <decrypted data length> |
122 | * load <master-key name> <decrypted data length> <encrypted iv + data> |
123 | * update <new-master-key name> |
124 | * |
125 | * Tokenizes a copy of the keyctl data, returning a pointer to each token, |
126 | * which is null terminated. |
127 | * |
128 | * On success returns 0, otherwise -EINVAL. |
129 | */ |
130 | static int datablob_parse(char *datablob, char **master_desc, |
131 | char **decrypted_datalen, char **hex_encoded_iv) |
132 | { |
133 | substring_t args[MAX_OPT_ARGS]; |
134 | int ret = -EINVAL; |
135 | int key_cmd; |
136 | char *p; |
137 | |
138 | p = strsep(&datablob, " \t"); |
139 | if (!p) |
140 | return ret; |
141 | key_cmd = match_token(p, key_tokens, args); |
142 | |
143 | *master_desc = strsep(&datablob, " \t"); |
144 | if (!*master_desc) |
145 | goto out; |
146 | |
147 | if (valid_master_desc(*master_desc, NULL) < 0) |
148 | goto out; |
149 | |
150 | if (decrypted_datalen) { |
151 | *decrypted_datalen = strsep(&datablob, " \t"); |
152 | if (!*decrypted_datalen) |
153 | goto out; |
154 | } |
155 | |
156 | switch (key_cmd) { |
157 | case Opt_new: |
158 | if (!decrypted_datalen) |
159 | break; |
160 | ret = 0; |
161 | break; |
162 | case Opt_load: |
163 | if (!decrypted_datalen) |
164 | break; |
165 | *hex_encoded_iv = strsep(&datablob, " \t"); |
166 | if (!*hex_encoded_iv) |
167 | break; |
168 | ret = 0; |
169 | break; |
170 | case Opt_update: |
171 | if (decrypted_datalen) |
172 | break; |
173 | ret = 0; |
174 | break; |
175 | case Opt_err: |
176 | break; |
177 | } |
178 | out: |
179 | return ret; |
180 | } |
181 | |
182 | /* |
183 | * datablob_format - format as an ascii string, before copying to userspace |
184 | */ |
185 | static char *datablob_format(struct encrypted_key_payload *epayload, |
186 | size_t asciiblob_len) |
187 | { |
188 | char *ascii_buf, *bufp; |
189 | u8 *iv = epayload->iv; |
190 | int len; |
191 | int i; |
192 | |
193 | ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL); |
194 | if (!ascii_buf) |
195 | goto out; |
196 | |
197 | ascii_buf[asciiblob_len] = '\0'; |
198 | |
199 | /* copy datablob master_desc and datalen strings */ |
200 | len = sprintf(ascii_buf, "%s %s ", epayload->master_desc, |
201 | epayload->datalen); |
202 | |
203 | /* convert the hex encoded iv, encrypted-data and HMAC to ascii */ |
204 | bufp = &ascii_buf[len]; |
205 | for (i = 0; i < (asciiblob_len - len) / 2; i++) |
206 | bufp = pack_hex_byte(bufp, iv[i]); |
207 | out: |
208 | return ascii_buf; |
209 | } |
210 | |
211 | /* |
212 | * request_trusted_key - request the trusted key |
213 | * |
214 | * Trusted keys are sealed to PCRs and other metadata. Although userspace |
215 | * manages both trusted/encrypted key-types, like the encrypted key type |
216 | * data, trusted key type data is not visible decrypted from userspace. |
217 | */ |
218 | static struct key *request_trusted_key(const char *trusted_desc, |
219 | u8 **master_key, size_t *master_keylen) |
220 | { |
221 | struct trusted_key_payload *tpayload; |
222 | struct key *tkey; |
223 | |
224 | tkey = request_key(&key_type_trusted, trusted_desc, NULL); |
225 | if (IS_ERR(tkey)) |
226 | goto error; |
227 | |
228 | down_read(&tkey->sem); |
229 | tpayload = rcu_dereference(tkey->payload.data); |
230 | *master_key = tpayload->key; |
231 | *master_keylen = tpayload->key_len; |
232 | error: |
233 | return tkey; |
234 | } |
235 | |
236 | /* |
237 | * request_user_key - request the user key |
238 | * |
239 | * Use a user provided key to encrypt/decrypt an encrypted-key. |
240 | */ |
241 | static struct key *request_user_key(const char *master_desc, u8 **master_key, |
242 | size_t *master_keylen) |
243 | { |
244 | struct user_key_payload *upayload; |
245 | struct key *ukey; |
246 | |
247 | ukey = request_key(&key_type_user, master_desc, NULL); |
248 | if (IS_ERR(ukey)) |
249 | goto error; |
250 | |
251 | down_read(&ukey->sem); |
252 | upayload = rcu_dereference(ukey->payload.data); |
253 | *master_key = upayload->data; |
254 | *master_keylen = upayload->datalen; |
255 | error: |
256 | return ukey; |
257 | } |
258 | |
259 | static struct sdesc *alloc_sdesc(struct crypto_shash *alg) |
260 | { |
261 | struct sdesc *sdesc; |
262 | int size; |
263 | |
264 | size = sizeof(struct shash_desc) + crypto_shash_descsize(alg); |
265 | sdesc = kmalloc(size, GFP_KERNEL); |
266 | if (!sdesc) |
267 | return ERR_PTR(-ENOMEM); |
268 | sdesc->shash.tfm = alg; |
269 | sdesc->shash.flags = 0x0; |
270 | return sdesc; |
271 | } |
272 | |
273 | static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen, |
274 | const u8 *buf, unsigned int buflen) |
275 | { |
276 | struct sdesc *sdesc; |
277 | int ret; |
278 | |
279 | sdesc = alloc_sdesc(hmacalg); |
280 | if (IS_ERR(sdesc)) { |
281 | pr_info("encrypted_key: can't alloc %s\n", hmac_alg); |
282 | return PTR_ERR(sdesc); |
283 | } |
284 | |
285 | ret = crypto_shash_setkey(hmacalg, key, keylen); |
286 | if (!ret) |
287 | ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest); |
288 | kfree(sdesc); |
289 | return ret; |
290 | } |
291 | |
292 | static int calc_hash(u8 *digest, const u8 *buf, unsigned int buflen) |
293 | { |
294 | struct sdesc *sdesc; |
295 | int ret; |
296 | |
297 | sdesc = alloc_sdesc(hashalg); |
298 | if (IS_ERR(sdesc)) { |
299 | pr_info("encrypted_key: can't alloc %s\n", hash_alg); |
300 | return PTR_ERR(sdesc); |
301 | } |
302 | |
303 | ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest); |
304 | kfree(sdesc); |
305 | return ret; |
306 | } |
307 | |
308 | enum derived_key_type { ENC_KEY, AUTH_KEY }; |
309 | |
310 | /* Derive authentication/encryption key from trusted key */ |
311 | static int get_derived_key(u8 *derived_key, enum derived_key_type key_type, |
312 | const u8 *master_key, size_t master_keylen) |
313 | { |
314 | u8 *derived_buf; |
315 | unsigned int derived_buf_len; |
316 | int ret; |
317 | |
318 | derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen; |
319 | if (derived_buf_len < HASH_SIZE) |
320 | derived_buf_len = HASH_SIZE; |
321 | |
322 | derived_buf = kzalloc(derived_buf_len, GFP_KERNEL); |
323 | if (!derived_buf) { |
324 | pr_err("encrypted_key: out of memory\n"); |
325 | return -ENOMEM; |
326 | } |
327 | if (key_type) |
328 | strcpy(derived_buf, "AUTH_KEY"); |
329 | else |
330 | strcpy(derived_buf, "ENC_KEY"); |
331 | |
332 | memcpy(derived_buf + strlen(derived_buf) + 1, master_key, |
333 | master_keylen); |
334 | ret = calc_hash(derived_key, derived_buf, derived_buf_len); |
335 | kfree(derived_buf); |
336 | return ret; |
337 | } |
338 | |
339 | static int init_blkcipher_desc(struct blkcipher_desc *desc, const u8 *key, |
340 | unsigned int key_len, const u8 *iv, |
341 | unsigned int ivsize) |
342 | { |
343 | int ret; |
344 | |
345 | desc->tfm = crypto_alloc_blkcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); |
346 | if (IS_ERR(desc->tfm)) { |
347 | pr_err("encrypted_key: failed to load %s transform (%ld)\n", |
348 | blkcipher_alg, PTR_ERR(desc->tfm)); |
349 | return PTR_ERR(desc->tfm); |
350 | } |
351 | desc->flags = 0; |
352 | |
353 | ret = crypto_blkcipher_setkey(desc->tfm, key, key_len); |
354 | if (ret < 0) { |
355 | pr_err("encrypted_key: failed to setkey (%d)\n", ret); |
356 | crypto_free_blkcipher(desc->tfm); |
357 | return ret; |
358 | } |
359 | crypto_blkcipher_set_iv(desc->tfm, iv, ivsize); |
360 | return 0; |
361 | } |
362 | |
363 | static struct key *request_master_key(struct encrypted_key_payload *epayload, |
364 | u8 **master_key, size_t *master_keylen) |
365 | { |
366 | struct key *mkey = NULL; |
367 | |
368 | if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX, |
369 | KEY_TRUSTED_PREFIX_LEN)) { |
370 | mkey = request_trusted_key(epayload->master_desc + |
371 | KEY_TRUSTED_PREFIX_LEN, |
372 | master_key, master_keylen); |
373 | } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX, |
374 | KEY_USER_PREFIX_LEN)) { |
375 | mkey = request_user_key(epayload->master_desc + |
376 | KEY_USER_PREFIX_LEN, |
377 | master_key, master_keylen); |
378 | } else |
379 | goto out; |
380 | |
381 | if (IS_ERR(mkey)) |
382 | pr_info("encrypted_key: key %s not found", |
383 | epayload->master_desc); |
384 | if (mkey) |
385 | dump_master_key(*master_key, *master_keylen); |
386 | out: |
387 | return mkey; |
388 | } |
389 | |
390 | /* Before returning data to userspace, encrypt decrypted data. */ |
391 | static int derived_key_encrypt(struct encrypted_key_payload *epayload, |
392 | const u8 *derived_key, |
393 | unsigned int derived_keylen) |
394 | { |
395 | struct scatterlist sg_in[2]; |
396 | struct scatterlist sg_out[1]; |
397 | struct blkcipher_desc desc; |
398 | unsigned int encrypted_datalen; |
399 | unsigned int padlen; |
400 | char pad[16]; |
401 | int ret; |
402 | |
403 | encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); |
404 | padlen = encrypted_datalen - epayload->decrypted_datalen; |
405 | |
406 | ret = init_blkcipher_desc(&desc, derived_key, derived_keylen, |
407 | epayload->iv, ivsize); |
408 | if (ret < 0) |
409 | goto out; |
410 | dump_decrypted_data(epayload); |
411 | |
412 | memset(pad, 0, sizeof pad); |
413 | sg_init_table(sg_in, 2); |
414 | sg_set_buf(&sg_in[0], epayload->decrypted_data, |
415 | epayload->decrypted_datalen); |
416 | sg_set_buf(&sg_in[1], pad, padlen); |
417 | |
418 | sg_init_table(sg_out, 1); |
419 | sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen); |
420 | |
421 | ret = crypto_blkcipher_encrypt(&desc, sg_out, sg_in, encrypted_datalen); |
422 | crypto_free_blkcipher(desc.tfm); |
423 | if (ret < 0) |
424 | pr_err("encrypted_key: failed to encrypt (%d)\n", ret); |
425 | else |
426 | dump_encrypted_data(epayload, encrypted_datalen); |
427 | out: |
428 | return ret; |
429 | } |
430 | |
431 | static int datablob_hmac_append(struct encrypted_key_payload *epayload, |
432 | const u8 *master_key, size_t master_keylen) |
433 | { |
434 | u8 derived_key[HASH_SIZE]; |
435 | u8 *digest; |
436 | int ret; |
437 | |
438 | ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); |
439 | if (ret < 0) |
440 | goto out; |
441 | |
442 | digest = epayload->master_desc + epayload->datablob_len; |
443 | ret = calc_hmac(digest, derived_key, sizeof derived_key, |
444 | epayload->master_desc, epayload->datablob_len); |
445 | if (!ret) |
446 | dump_hmac(NULL, digest, HASH_SIZE); |
447 | out: |
448 | return ret; |
449 | } |
450 | |
451 | /* verify HMAC before decrypting encrypted key */ |
452 | static int datablob_hmac_verify(struct encrypted_key_payload *epayload, |
453 | const u8 *master_key, size_t master_keylen) |
454 | { |
455 | u8 derived_key[HASH_SIZE]; |
456 | u8 digest[HASH_SIZE]; |
457 | int ret; |
458 | |
459 | ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); |
460 | if (ret < 0) |
461 | goto out; |
462 | |
463 | ret = calc_hmac(digest, derived_key, sizeof derived_key, |
464 | epayload->master_desc, epayload->datablob_len); |
465 | if (ret < 0) |
466 | goto out; |
467 | ret = memcmp(digest, epayload->master_desc + epayload->datablob_len, |
468 | sizeof digest); |
469 | if (ret) { |
470 | ret = -EINVAL; |
471 | dump_hmac("datablob", |
472 | epayload->master_desc + epayload->datablob_len, |
473 | HASH_SIZE); |
474 | dump_hmac("calc", digest, HASH_SIZE); |
475 | } |
476 | out: |
477 | return ret; |
478 | } |
479 | |
480 | static int derived_key_decrypt(struct encrypted_key_payload *epayload, |
481 | const u8 *derived_key, |
482 | unsigned int derived_keylen) |
483 | { |
484 | struct scatterlist sg_in[1]; |
485 | struct scatterlist sg_out[2]; |
486 | struct blkcipher_desc desc; |
487 | unsigned int encrypted_datalen; |
488 | char pad[16]; |
489 | int ret; |
490 | |
491 | encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); |
492 | ret = init_blkcipher_desc(&desc, derived_key, derived_keylen, |
493 | epayload->iv, ivsize); |
494 | if (ret < 0) |
495 | goto out; |
496 | dump_encrypted_data(epayload, encrypted_datalen); |
497 | |
498 | memset(pad, 0, sizeof pad); |
499 | sg_init_table(sg_in, 1); |
500 | sg_init_table(sg_out, 2); |
501 | sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen); |
502 | sg_set_buf(&sg_out[0], epayload->decrypted_data, |
503 | epayload->decrypted_datalen); |
504 | sg_set_buf(&sg_out[1], pad, sizeof pad); |
505 | |
506 | ret = crypto_blkcipher_decrypt(&desc, sg_out, sg_in, encrypted_datalen); |
507 | crypto_free_blkcipher(desc.tfm); |
508 | if (ret < 0) |
509 | goto out; |
510 | dump_decrypted_data(epayload); |
511 | out: |
512 | return ret; |
513 | } |
514 | |
515 | /* Allocate memory for decrypted key and datablob. */ |
516 | static struct encrypted_key_payload *encrypted_key_alloc(struct key *key, |
517 | const char *master_desc, |
518 | const char *datalen) |
519 | { |
520 | struct encrypted_key_payload *epayload = NULL; |
521 | unsigned short datablob_len; |
522 | unsigned short decrypted_datalen; |
523 | unsigned int encrypted_datalen; |
524 | long dlen; |
525 | int ret; |
526 | |
527 | ret = strict_strtol(datalen, 10, &dlen); |
528 | if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE) |
529 | return ERR_PTR(-EINVAL); |
530 | |
531 | decrypted_datalen = dlen; |
532 | encrypted_datalen = roundup(decrypted_datalen, blksize); |
533 | |
534 | datablob_len = strlen(master_desc) + 1 + strlen(datalen) + 1 |
535 | + ivsize + 1 + encrypted_datalen; |
536 | |
537 | ret = key_payload_reserve(key, decrypted_datalen + datablob_len |
538 | + HASH_SIZE + 1); |
539 | if (ret < 0) |
540 | return ERR_PTR(ret); |
541 | |
542 | epayload = kzalloc(sizeof(*epayload) + decrypted_datalen + |
543 | datablob_len + HASH_SIZE + 1, GFP_KERNEL); |
544 | if (!epayload) |
545 | return ERR_PTR(-ENOMEM); |
546 | |
547 | epayload->decrypted_datalen = decrypted_datalen; |
548 | epayload->datablob_len = datablob_len; |
549 | return epayload; |
550 | } |
551 | |
552 | static int encrypted_key_decrypt(struct encrypted_key_payload *epayload, |
553 | const char *hex_encoded_iv) |
554 | { |
555 | struct key *mkey; |
556 | u8 derived_key[HASH_SIZE]; |
557 | u8 *master_key; |
558 | u8 *hmac; |
559 | const char *hex_encoded_data; |
560 | unsigned int encrypted_datalen; |
561 | size_t master_keylen; |
562 | size_t asciilen; |
563 | int ret; |
564 | |
565 | encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); |
566 | asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2; |
567 | if (strlen(hex_encoded_iv) != asciilen) |
568 | return -EINVAL; |
569 | |
570 | hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2; |
571 | hex2bin(epayload->iv, hex_encoded_iv, ivsize); |
572 | hex2bin(epayload->encrypted_data, hex_encoded_data, encrypted_datalen); |
573 | |
574 | hmac = epayload->master_desc + epayload->datablob_len; |
575 | hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2), HASH_SIZE); |
576 | |
577 | mkey = request_master_key(epayload, &master_key, &master_keylen); |
578 | if (IS_ERR(mkey)) |
579 | return PTR_ERR(mkey); |
580 | |
581 | ret = datablob_hmac_verify(epayload, master_key, master_keylen); |
582 | if (ret < 0) { |
583 | pr_err("encrypted_key: bad hmac (%d)\n", ret); |
584 | goto out; |
585 | } |
586 | |
587 | ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); |
588 | if (ret < 0) |
589 | goto out; |
590 | |
591 | ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key); |
592 | if (ret < 0) |
593 | pr_err("encrypted_key: failed to decrypt key (%d)\n", ret); |
594 | out: |
595 | up_read(&mkey->sem); |
596 | key_put(mkey); |
597 | return ret; |
598 | } |
599 | |
600 | static void __ekey_init(struct encrypted_key_payload *epayload, |
601 | const char *master_desc, const char *datalen) |
602 | { |
603 | epayload->master_desc = epayload->decrypted_data |
604 | + epayload->decrypted_datalen; |
605 | epayload->datalen = epayload->master_desc + strlen(master_desc) + 1; |
606 | epayload->iv = epayload->datalen + strlen(datalen) + 1; |
607 | epayload->encrypted_data = epayload->iv + ivsize + 1; |
608 | |
609 | memcpy(epayload->master_desc, master_desc, strlen(master_desc)); |
610 | memcpy(epayload->datalen, datalen, strlen(datalen)); |
611 | } |
612 | |
613 | /* |
614 | * encrypted_init - initialize an encrypted key |
615 | * |
616 | * For a new key, use a random number for both the iv and data |
617 | * itself. For an old key, decrypt the hex encoded data. |
618 | */ |
619 | static int encrypted_init(struct encrypted_key_payload *epayload, |
620 | const char *master_desc, const char *datalen, |
621 | const char *hex_encoded_iv) |
622 | { |
623 | int ret = 0; |
624 | |
625 | __ekey_init(epayload, master_desc, datalen); |
626 | if (!hex_encoded_iv) { |
627 | get_random_bytes(epayload->iv, ivsize); |
628 | |
629 | get_random_bytes(epayload->decrypted_data, |
630 | epayload->decrypted_datalen); |
631 | } else |
632 | ret = encrypted_key_decrypt(epayload, hex_encoded_iv); |
633 | return ret; |
634 | } |
635 | |
636 | /* |
637 | * encrypted_instantiate - instantiate an encrypted key |
638 | * |
639 | * Decrypt an existing encrypted datablob or create a new encrypted key |
640 | * based on a kernel random number. |
641 | * |
642 | * On success, return 0. Otherwise return errno. |
643 | */ |
644 | static int encrypted_instantiate(struct key *key, const void *data, |
645 | size_t datalen) |
646 | { |
647 | struct encrypted_key_payload *epayload = NULL; |
648 | char *datablob = NULL; |
649 | char *master_desc = NULL; |
650 | char *decrypted_datalen = NULL; |
651 | char *hex_encoded_iv = NULL; |
652 | int ret; |
653 | |
654 | if (datalen <= 0 || datalen > 32767 || !data) |
655 | return -EINVAL; |
656 | |
657 | datablob = kmalloc(datalen + 1, GFP_KERNEL); |
658 | if (!datablob) |
659 | return -ENOMEM; |
660 | datablob[datalen] = 0; |
661 | memcpy(datablob, data, datalen); |
662 | ret = datablob_parse(datablob, &master_desc, &decrypted_datalen, |
663 | &hex_encoded_iv); |
664 | if (ret < 0) |
665 | goto out; |
666 | |
667 | epayload = encrypted_key_alloc(key, master_desc, decrypted_datalen); |
668 | if (IS_ERR(epayload)) { |
669 | ret = PTR_ERR(epayload); |
670 | goto out; |
671 | } |
672 | ret = encrypted_init(epayload, master_desc, decrypted_datalen, |
673 | hex_encoded_iv); |
674 | if (ret < 0) { |
675 | kfree(epayload); |
676 | goto out; |
677 | } |
678 | |
679 | rcu_assign_pointer(key->payload.data, epayload); |
680 | out: |
681 | kfree(datablob); |
682 | return ret; |
683 | } |
684 | |
685 | static void encrypted_rcu_free(struct rcu_head *rcu) |
686 | { |
687 | struct encrypted_key_payload *epayload; |
688 | |
689 | epayload = container_of(rcu, struct encrypted_key_payload, rcu); |
690 | memset(epayload->decrypted_data, 0, epayload->decrypted_datalen); |
691 | kfree(epayload); |
692 | } |
693 | |
694 | /* |
695 | * encrypted_update - update the master key description |
696 | * |
697 | * Change the master key description for an existing encrypted key. |
698 | * The next read will return an encrypted datablob using the new |
699 | * master key description. |
700 | * |
701 | * On success, return 0. Otherwise return errno. |
702 | */ |
703 | static int encrypted_update(struct key *key, const void *data, size_t datalen) |
704 | { |
705 | struct encrypted_key_payload *epayload = key->payload.data; |
706 | struct encrypted_key_payload *new_epayload; |
707 | char *buf; |
708 | char *new_master_desc = NULL; |
709 | int ret = 0; |
710 | |
711 | if (datalen <= 0 || datalen > 32767 || !data) |
712 | return -EINVAL; |
713 | |
714 | buf = kmalloc(datalen + 1, GFP_KERNEL); |
715 | if (!buf) |
716 | return -ENOMEM; |
717 | |
718 | buf[datalen] = 0; |
719 | memcpy(buf, data, datalen); |
720 | ret = datablob_parse(buf, &new_master_desc, NULL, NULL); |
721 | if (ret < 0) |
722 | goto out; |
723 | |
724 | ret = valid_master_desc(new_master_desc, epayload->master_desc); |
725 | if (ret < 0) |
726 | goto out; |
727 | |
728 | new_epayload = encrypted_key_alloc(key, new_master_desc, |
729 | epayload->datalen); |
730 | if (IS_ERR(new_epayload)) { |
731 | ret = PTR_ERR(new_epayload); |
732 | goto out; |
733 | } |
734 | |
735 | __ekey_init(new_epayload, new_master_desc, epayload->datalen); |
736 | |
737 | memcpy(new_epayload->iv, epayload->iv, ivsize); |
738 | memcpy(new_epayload->decrypted_data, epayload->decrypted_data, |
739 | epayload->decrypted_datalen); |
740 | |
741 | rcu_assign_pointer(key->payload.data, new_epayload); |
742 | call_rcu(&epayload->rcu, encrypted_rcu_free); |
743 | out: |
744 | kfree(buf); |
745 | return ret; |
746 | } |
747 | |
748 | /* |
749 | * encrypted_read - format and copy the encrypted data to userspace |
750 | * |
751 | * The resulting datablob format is: |
752 | * <master-key name> <decrypted data length> <encrypted iv> <encrypted data> |
753 | * |
754 | * On success, return to userspace the encrypted key datablob size. |
755 | */ |
756 | static long encrypted_read(const struct key *key, char __user *buffer, |
757 | size_t buflen) |
758 | { |
759 | struct encrypted_key_payload *epayload; |
760 | struct key *mkey; |
761 | u8 *master_key; |
762 | size_t master_keylen; |
763 | char derived_key[HASH_SIZE]; |
764 | char *ascii_buf; |
765 | size_t asciiblob_len; |
766 | int ret; |
767 | |
768 | epayload = rcu_dereference_protected(key->payload.data, |
769 | rwsem_is_locked(&((struct key *)key)->sem)); |
770 | |
771 | /* returns the hex encoded iv, encrypted-data, and hmac as ascii */ |
772 | asciiblob_len = epayload->datablob_len + ivsize + 1 |
773 | + roundup(epayload->decrypted_datalen, blksize) |
774 | + (HASH_SIZE * 2); |
775 | |
776 | if (!buffer || buflen < asciiblob_len) |
777 | return asciiblob_len; |
778 | |
779 | mkey = request_master_key(epayload, &master_key, &master_keylen); |
780 | if (IS_ERR(mkey)) |
781 | return PTR_ERR(mkey); |
782 | |
783 | ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); |
784 | if (ret < 0) |
785 | goto out; |
786 | |
787 | ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key); |
788 | if (ret < 0) |
789 | goto out; |
790 | |
791 | ret = datablob_hmac_append(epayload, master_key, master_keylen); |
792 | if (ret < 0) |
793 | goto out; |
794 | |
795 | ascii_buf = datablob_format(epayload, asciiblob_len); |
796 | if (!ascii_buf) { |
797 | ret = -ENOMEM; |
798 | goto out; |
799 | } |
800 | |
801 | up_read(&mkey->sem); |
802 | key_put(mkey); |
803 | |
804 | if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0) |
805 | ret = -EFAULT; |
806 | kfree(ascii_buf); |
807 | |
808 | return asciiblob_len; |
809 | out: |
810 | up_read(&mkey->sem); |
811 | key_put(mkey); |
812 | return ret; |
813 | } |
814 | |
815 | /* |
816 | * encrypted_destroy - before freeing the key, clear the decrypted data |
817 | * |
818 | * Before freeing the key, clear the memory containing the decrypted |
819 | * key data. |
820 | */ |
821 | static void encrypted_destroy(struct key *key) |
822 | { |
823 | struct encrypted_key_payload *epayload = key->payload.data; |
824 | |
825 | if (!epayload) |
826 | return; |
827 | |
828 | memset(epayload->decrypted_data, 0, epayload->decrypted_datalen); |
829 | kfree(key->payload.data); |
830 | } |
831 | |
832 | struct key_type key_type_encrypted = { |
833 | .name = "encrypted", |
834 | .instantiate = encrypted_instantiate, |
835 | .update = encrypted_update, |
836 | .match = user_match, |
837 | .destroy = encrypted_destroy, |
838 | .describe = user_describe, |
839 | .read = encrypted_read, |
840 | }; |
841 | EXPORT_SYMBOL_GPL(key_type_encrypted); |
842 | |
843 | static void encrypted_shash_release(void) |
844 | { |
845 | if (hashalg) |
846 | crypto_free_shash(hashalg); |
847 | if (hmacalg) |
848 | crypto_free_shash(hmacalg); |
849 | } |
850 | |
851 | static int __init encrypted_shash_alloc(void) |
852 | { |
853 | int ret; |
854 | |
855 | hmacalg = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC); |
856 | if (IS_ERR(hmacalg)) { |
857 | pr_info("encrypted_key: could not allocate crypto %s\n", |
858 | hmac_alg); |
859 | return PTR_ERR(hmacalg); |
860 | } |
861 | |
862 | hashalg = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC); |
863 | if (IS_ERR(hashalg)) { |
864 | pr_info("encrypted_key: could not allocate crypto %s\n", |
865 | hash_alg); |
866 | ret = PTR_ERR(hashalg); |
867 | goto hashalg_fail; |
868 | } |
869 | |
870 | return 0; |
871 | |
872 | hashalg_fail: |
873 | crypto_free_shash(hmacalg); |
874 | return ret; |
875 | } |
876 | |
877 | static int __init init_encrypted(void) |
878 | { |
879 | int ret; |
880 | |
881 | ret = encrypted_shash_alloc(); |
882 | if (ret < 0) |
883 | return ret; |
884 | ret = register_key_type(&key_type_encrypted); |
885 | if (ret < 0) |
886 | goto out; |
887 | return aes_get_sizes(); |
888 | out: |
889 | encrypted_shash_release(); |
890 | return ret; |
891 | |
892 | } |
893 | |
894 | static void __exit cleanup_encrypted(void) |
895 | { |
896 | encrypted_shash_release(); |
897 | unregister_key_type(&key_type_encrypted); |
898 | } |
899 | |
900 | late_initcall(init_encrypted); |
901 | module_exit(cleanup_encrypted); |
902 | |
903 | MODULE_LICENSE("GPL"); |
904 |
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