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7e70cb49 MZ |
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> | |
93ae86e7 | 20 | #include <linux/err.h> |
7e70cb49 MZ |
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_defined.h" | |
34 | ||
35 | #define KEY_TRUSTED_PREFIX "trusted:" | |
36 | #define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1) | |
37 | #define KEY_USER_PREFIX "user:" | |
38 | #define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1) | |
39 | ||
40 | #define HASH_SIZE SHA256_DIGEST_SIZE | |
41 | #define MAX_DATA_SIZE 4096 | |
42 | #define MIN_DATA_SIZE 20 | |
43 | ||
44 | static const char hash_alg[] = "sha256"; | |
45 | static const char hmac_alg[] = "hmac(sha256)"; | |
46 | static const char blkcipher_alg[] = "cbc(aes)"; | |
47 | static unsigned int ivsize; | |
48 | static int blksize; | |
49 | ||
50 | struct sdesc { | |
51 | struct shash_desc shash; | |
52 | char ctx[]; | |
53 | }; | |
54 | ||
55 | static struct crypto_shash *hashalg; | |
56 | static struct crypto_shash *hmacalg; | |
57 | ||
58 | enum { | |
59 | Opt_err = -1, Opt_new, Opt_load, Opt_update | |
60 | }; | |
61 | ||
62 | static const match_table_t key_tokens = { | |
63 | {Opt_new, "new"}, | |
64 | {Opt_load, "load"}, | |
65 | {Opt_update, "update"}, | |
66 | {Opt_err, NULL} | |
67 | }; | |
68 | ||
69 | static int aes_get_sizes(void) | |
70 | { | |
71 | struct crypto_blkcipher *tfm; | |
72 | ||
73 | tfm = crypto_alloc_blkcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); | |
74 | if (IS_ERR(tfm)) { | |
75 | pr_err("encrypted_key: failed to alloc_cipher (%ld)\n", | |
76 | PTR_ERR(tfm)); | |
77 | return PTR_ERR(tfm); | |
78 | } | |
79 | ivsize = crypto_blkcipher_ivsize(tfm); | |
80 | blksize = crypto_blkcipher_blocksize(tfm); | |
81 | crypto_free_blkcipher(tfm); | |
82 | return 0; | |
83 | } | |
84 | ||
85 | /* | |
86 | * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key | |
87 | * | |
88 | * key-type:= "trusted:" | "encrypted:" | |
89 | * desc:= master-key description | |
90 | * | |
91 | * Verify that 'key-type' is valid and that 'desc' exists. On key update, | |
92 | * only the master key description is permitted to change, not the key-type. | |
93 | * The key-type remains constant. | |
94 | * | |
95 | * On success returns 0, otherwise -EINVAL. | |
96 | */ | |
97 | static int valid_master_desc(const char *new_desc, const char *orig_desc) | |
98 | { | |
99 | if (!memcmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) { | |
100 | if (strlen(new_desc) == KEY_TRUSTED_PREFIX_LEN) | |
101 | goto out; | |
102 | if (orig_desc) | |
103 | if (memcmp(new_desc, orig_desc, KEY_TRUSTED_PREFIX_LEN)) | |
104 | goto out; | |
105 | } else if (!memcmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) { | |
106 | if (strlen(new_desc) == KEY_USER_PREFIX_LEN) | |
107 | goto out; | |
108 | if (orig_desc) | |
109 | if (memcmp(new_desc, orig_desc, KEY_USER_PREFIX_LEN)) | |
110 | goto out; | |
111 | } else | |
112 | goto out; | |
113 | return 0; | |
114 | out: | |
115 | return -EINVAL; | |
116 | } | |
117 | ||
118 | /* | |
119 | * datablob_parse - parse the keyctl data | |
120 | * | |
121 | * datablob format: | |
122 | * new <master-key name> <decrypted data length> | |
123 | * load <master-key name> <decrypted data length> <encrypted iv + data> | |
124 | * update <new-master-key name> | |
125 | * | |
126 | * Tokenizes a copy of the keyctl data, returning a pointer to each token, | |
127 | * which is null terminated. | |
128 | * | |
129 | * On success returns 0, otherwise -EINVAL. | |
130 | */ | |
131 | static int datablob_parse(char *datablob, char **master_desc, | |
132 | char **decrypted_datalen, char **hex_encoded_iv, | |
133 | char **hex_encoded_data) | |
134 | { | |
135 | substring_t args[MAX_OPT_ARGS]; | |
136 | int ret = -EINVAL; | |
137 | int key_cmd; | |
138 | char *p; | |
139 | ||
140 | p = strsep(&datablob, " \t"); | |
141 | if (!p) | |
142 | return ret; | |
143 | key_cmd = match_token(p, key_tokens, args); | |
144 | ||
145 | *master_desc = strsep(&datablob, " \t"); | |
146 | if (!*master_desc) | |
147 | goto out; | |
148 | ||
149 | if (valid_master_desc(*master_desc, NULL) < 0) | |
150 | goto out; | |
151 | ||
152 | if (decrypted_datalen) { | |
153 | *decrypted_datalen = strsep(&datablob, " \t"); | |
154 | if (!*decrypted_datalen) | |
155 | goto out; | |
156 | } | |
157 | ||
158 | switch (key_cmd) { | |
159 | case Opt_new: | |
160 | if (!decrypted_datalen) | |
161 | break; | |
162 | ret = 0; | |
163 | break; | |
164 | case Opt_load: | |
165 | if (!decrypted_datalen) | |
166 | break; | |
167 | *hex_encoded_iv = strsep(&datablob, " \t"); | |
168 | if (!*hex_encoded_iv) | |
169 | break; | |
170 | *hex_encoded_data = *hex_encoded_iv + (2 * ivsize) + 2; | |
171 | ret = 0; | |
172 | break; | |
173 | case Opt_update: | |
174 | if (decrypted_datalen) | |
175 | break; | |
176 | ret = 0; | |
177 | break; | |
178 | case Opt_err: | |
179 | break; | |
180 | } | |
181 | out: | |
182 | return ret; | |
183 | } | |
184 | ||
185 | /* | |
186 | * datablob_format - format as an ascii string, before copying to userspace | |
187 | */ | |
188 | static char *datablob_format(struct encrypted_key_payload *epayload, | |
189 | size_t asciiblob_len) | |
190 | { | |
191 | char *ascii_buf, *bufp; | |
192 | u8 *iv = epayload->iv; | |
193 | int len; | |
194 | int i; | |
195 | ||
196 | ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL); | |
197 | if (!ascii_buf) | |
198 | goto out; | |
199 | ||
200 | ascii_buf[asciiblob_len] = '\0'; | |
201 | ||
202 | /* copy datablob master_desc and datalen strings */ | |
203 | len = sprintf(ascii_buf, "%s %s ", epayload->master_desc, | |
204 | epayload->datalen); | |
205 | ||
206 | /* convert the hex encoded iv, encrypted-data and HMAC to ascii */ | |
207 | bufp = &ascii_buf[len]; | |
208 | for (i = 0; i < (asciiblob_len - len) / 2; i++) | |
209 | bufp = pack_hex_byte(bufp, iv[i]); | |
210 | out: | |
211 | return ascii_buf; | |
212 | } | |
213 | ||
214 | /* | |
215 | * request_trusted_key - request the trusted key | |
216 | * | |
217 | * Trusted keys are sealed to PCRs and other metadata. Although userspace | |
218 | * manages both trusted/encrypted key-types, like the encrypted key type | |
219 | * data, trusted key type data is not visible decrypted from userspace. | |
220 | */ | |
221 | static struct key *request_trusted_key(const char *trusted_desc, | |
222 | u8 **master_key, | |
223 | unsigned int *master_keylen) | |
224 | { | |
225 | struct trusted_key_payload *tpayload; | |
226 | struct key *tkey; | |
227 | ||
228 | tkey = request_key(&key_type_trusted, trusted_desc, NULL); | |
229 | if (IS_ERR(tkey)) | |
230 | goto error; | |
231 | ||
232 | down_read(&tkey->sem); | |
233 | tpayload = rcu_dereference(tkey->payload.data); | |
234 | *master_key = tpayload->key; | |
235 | *master_keylen = tpayload->key_len; | |
236 | error: | |
237 | return tkey; | |
238 | } | |
239 | ||
240 | /* | |
241 | * request_user_key - request the user key | |
242 | * | |
243 | * Use a user provided key to encrypt/decrypt an encrypted-key. | |
244 | */ | |
245 | static struct key *request_user_key(const char *master_desc, u8 **master_key, | |
246 | unsigned int *master_keylen) | |
247 | { | |
248 | struct user_key_payload *upayload; | |
249 | struct key *ukey; | |
250 | ||
251 | ukey = request_key(&key_type_user, master_desc, NULL); | |
252 | if (IS_ERR(ukey)) | |
253 | goto error; | |
254 | ||
255 | down_read(&ukey->sem); | |
256 | upayload = rcu_dereference(ukey->payload.data); | |
257 | *master_key = upayload->data; | |
258 | *master_keylen = upayload->datalen; | |
259 | error: | |
260 | return ukey; | |
261 | } | |
262 | ||
263 | static struct sdesc *init_sdesc(struct crypto_shash *alg) | |
264 | { | |
265 | struct sdesc *sdesc; | |
266 | int size; | |
267 | ||
268 | size = sizeof(struct shash_desc) + crypto_shash_descsize(alg); | |
269 | sdesc = kmalloc(size, GFP_KERNEL); | |
270 | if (!sdesc) | |
271 | return ERR_PTR(-ENOMEM); | |
272 | sdesc->shash.tfm = alg; | |
273 | sdesc->shash.flags = 0x0; | |
274 | return sdesc; | |
275 | } | |
276 | ||
277 | static int calc_hmac(u8 *digest, const u8 *key, const unsigned int keylen, | |
278 | const u8 *buf, const unsigned int buflen) | |
279 | { | |
280 | struct sdesc *sdesc; | |
281 | int ret; | |
282 | ||
283 | sdesc = init_sdesc(hmacalg); | |
284 | if (IS_ERR(sdesc)) { | |
285 | pr_info("encrypted_key: can't alloc %s\n", hmac_alg); | |
286 | return PTR_ERR(sdesc); | |
287 | } | |
288 | ||
289 | ret = crypto_shash_setkey(hmacalg, key, keylen); | |
290 | if (!ret) | |
291 | ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest); | |
292 | kfree(sdesc); | |
293 | return ret; | |
294 | } | |
295 | ||
296 | static int calc_hash(u8 *digest, const u8 *buf, const unsigned int buflen) | |
297 | { | |
298 | struct sdesc *sdesc; | |
299 | int ret; | |
300 | ||
301 | sdesc = init_sdesc(hashalg); | |
302 | if (IS_ERR(sdesc)) { | |
303 | pr_info("encrypted_key: can't alloc %s\n", hash_alg); | |
304 | return PTR_ERR(sdesc); | |
305 | } | |
306 | ||
307 | ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest); | |
308 | kfree(sdesc); | |
309 | return ret; | |
310 | } | |
311 | ||
312 | enum derived_key_type { ENC_KEY, AUTH_KEY }; | |
313 | ||
314 | /* Derive authentication/encryption key from trusted key */ | |
315 | static int get_derived_key(u8 *derived_key, enum derived_key_type key_type, | |
316 | const u8 *master_key, | |
317 | const unsigned int master_keylen) | |
318 | { | |
319 | u8 *derived_buf; | |
320 | unsigned int derived_buf_len; | |
321 | int ret; | |
322 | ||
323 | derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen; | |
324 | if (derived_buf_len < HASH_SIZE) | |
325 | derived_buf_len = HASH_SIZE; | |
326 | ||
327 | derived_buf = kzalloc(derived_buf_len, GFP_KERNEL); | |
328 | if (!derived_buf) { | |
329 | pr_err("encrypted_key: out of memory\n"); | |
330 | return -ENOMEM; | |
331 | } | |
332 | if (key_type) | |
333 | strcpy(derived_buf, "AUTH_KEY"); | |
334 | else | |
335 | strcpy(derived_buf, "ENC_KEY"); | |
336 | ||
337 | memcpy(derived_buf + strlen(derived_buf) + 1, master_key, | |
338 | master_keylen); | |
339 | ret = calc_hash(derived_key, derived_buf, derived_buf_len); | |
340 | kfree(derived_buf); | |
341 | return ret; | |
342 | } | |
343 | ||
344 | static int init_blkcipher_desc(struct blkcipher_desc *desc, const u8 *key, | |
345 | const unsigned int key_len, const u8 *iv, | |
346 | const unsigned int ivsize) | |
347 | { | |
348 | int ret; | |
349 | ||
350 | desc->tfm = crypto_alloc_blkcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); | |
351 | if (IS_ERR(desc->tfm)) { | |
352 | pr_err("encrypted_key: failed to load %s transform (%ld)\n", | |
353 | blkcipher_alg, PTR_ERR(desc->tfm)); | |
354 | return PTR_ERR(desc->tfm); | |
355 | } | |
356 | desc->flags = 0; | |
357 | ||
358 | ret = crypto_blkcipher_setkey(desc->tfm, key, key_len); | |
359 | if (ret < 0) { | |
360 | pr_err("encrypted_key: failed to setkey (%d)\n", ret); | |
361 | crypto_free_blkcipher(desc->tfm); | |
362 | return ret; | |
363 | } | |
364 | crypto_blkcipher_set_iv(desc->tfm, iv, ivsize); | |
365 | return 0; | |
366 | } | |
367 | ||
368 | static struct key *request_master_key(struct encrypted_key_payload *epayload, | |
369 | u8 **master_key, | |
370 | unsigned int *master_keylen) | |
371 | { | |
372 | struct key *mkey = NULL; | |
373 | ||
374 | if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX, | |
375 | KEY_TRUSTED_PREFIX_LEN)) { | |
376 | mkey = request_trusted_key(epayload->master_desc + | |
377 | KEY_TRUSTED_PREFIX_LEN, | |
378 | master_key, master_keylen); | |
379 | } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX, | |
380 | KEY_USER_PREFIX_LEN)) { | |
381 | mkey = request_user_key(epayload->master_desc + | |
382 | KEY_USER_PREFIX_LEN, | |
383 | master_key, master_keylen); | |
384 | } else | |
385 | goto out; | |
386 | ||
387 | if (IS_ERR(mkey)) | |
388 | pr_info("encrypted_key: key %s not found", | |
389 | epayload->master_desc); | |
390 | if (mkey) | |
391 | dump_master_key(*master_key, *master_keylen); | |
392 | out: | |
393 | return mkey; | |
394 | } | |
395 | ||
396 | /* Before returning data to userspace, encrypt decrypted data. */ | |
397 | static int derived_key_encrypt(struct encrypted_key_payload *epayload, | |
398 | const u8 *derived_key, | |
399 | const unsigned int derived_keylen) | |
400 | { | |
401 | struct scatterlist sg_in[2]; | |
402 | struct scatterlist sg_out[1]; | |
403 | struct blkcipher_desc desc; | |
404 | unsigned int encrypted_datalen; | |
405 | unsigned int padlen; | |
406 | char pad[16]; | |
407 | int ret; | |
408 | ||
409 | encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); | |
410 | padlen = encrypted_datalen - epayload->decrypted_datalen; | |
411 | ||
412 | ret = init_blkcipher_desc(&desc, derived_key, derived_keylen, | |
413 | epayload->iv, ivsize); | |
414 | if (ret < 0) | |
415 | goto out; | |
416 | dump_decrypted_data(epayload); | |
417 | ||
418 | memset(pad, 0, sizeof pad); | |
419 | sg_init_table(sg_in, 2); | |
420 | sg_set_buf(&sg_in[0], epayload->decrypted_data, | |
421 | epayload->decrypted_datalen); | |
422 | sg_set_buf(&sg_in[1], pad, padlen); | |
423 | ||
424 | sg_init_table(sg_out, 1); | |
425 | sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen); | |
426 | ||
427 | ret = crypto_blkcipher_encrypt(&desc, sg_out, sg_in, encrypted_datalen); | |
428 | crypto_free_blkcipher(desc.tfm); | |
429 | if (ret < 0) | |
430 | pr_err("encrypted_key: failed to encrypt (%d)\n", ret); | |
431 | else | |
432 | dump_encrypted_data(epayload, encrypted_datalen); | |
433 | out: | |
434 | return ret; | |
435 | } | |
436 | ||
437 | static int datablob_hmac_append(struct encrypted_key_payload *epayload, | |
438 | const u8 *master_key, | |
439 | const unsigned int master_keylen) | |
440 | { | |
441 | u8 derived_key[HASH_SIZE]; | |
442 | u8 *digest; | |
443 | int ret; | |
444 | ||
445 | ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); | |
446 | if (ret < 0) | |
447 | goto out; | |
448 | ||
449 | digest = epayload->master_desc + epayload->datablob_len; | |
450 | ret = calc_hmac(digest, derived_key, sizeof derived_key, | |
451 | epayload->master_desc, epayload->datablob_len); | |
452 | if (!ret) | |
453 | dump_hmac(NULL, digest, HASH_SIZE); | |
454 | out: | |
455 | return ret; | |
456 | } | |
457 | ||
458 | /* verify HMAC before decrypting encrypted key */ | |
459 | static int datablob_hmac_verify(struct encrypted_key_payload *epayload, | |
460 | const u8 *master_key, | |
461 | const unsigned int master_keylen) | |
462 | { | |
463 | u8 derived_key[HASH_SIZE]; | |
464 | u8 digest[HASH_SIZE]; | |
465 | int ret; | |
466 | ||
467 | ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); | |
468 | if (ret < 0) | |
469 | goto out; | |
470 | ||
471 | ret = calc_hmac(digest, derived_key, sizeof derived_key, | |
472 | epayload->master_desc, epayload->datablob_len); | |
473 | if (ret < 0) | |
474 | goto out; | |
475 | ret = memcmp(digest, epayload->master_desc + epayload->datablob_len, | |
476 | sizeof digest); | |
477 | if (ret) { | |
478 | ret = -EINVAL; | |
479 | dump_hmac("datablob", | |
480 | epayload->master_desc + epayload->datablob_len, | |
481 | HASH_SIZE); | |
482 | dump_hmac("calc", digest, HASH_SIZE); | |
483 | } | |
484 | out: | |
485 | return ret; | |
486 | } | |
487 | ||
488 | static int derived_key_decrypt(struct encrypted_key_payload *epayload, | |
489 | const u8 *derived_key, | |
490 | const unsigned int derived_keylen) | |
491 | { | |
492 | struct scatterlist sg_in[1]; | |
493 | struct scatterlist sg_out[2]; | |
494 | struct blkcipher_desc desc; | |
495 | unsigned int encrypted_datalen; | |
496 | char pad[16]; | |
497 | int ret; | |
498 | ||
499 | encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); | |
500 | ret = init_blkcipher_desc(&desc, derived_key, derived_keylen, | |
501 | epayload->iv, ivsize); | |
502 | if (ret < 0) | |
503 | goto out; | |
504 | dump_encrypted_data(epayload, encrypted_datalen); | |
505 | ||
506 | memset(pad, 0, sizeof pad); | |
507 | sg_init_table(sg_in, 1); | |
508 | sg_init_table(sg_out, 2); | |
509 | sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen); | |
510 | sg_set_buf(&sg_out[0], epayload->decrypted_data, | |
511 | (unsigned int)epayload->decrypted_datalen); | |
512 | sg_set_buf(&sg_out[1], pad, sizeof pad); | |
513 | ||
514 | ret = crypto_blkcipher_decrypt(&desc, sg_out, sg_in, encrypted_datalen); | |
515 | crypto_free_blkcipher(desc.tfm); | |
516 | if (ret < 0) | |
517 | goto out; | |
518 | dump_decrypted_data(epayload); | |
519 | out: | |
520 | return ret; | |
521 | } | |
522 | ||
523 | /* Allocate memory for decrypted key and datablob. */ | |
524 | static struct encrypted_key_payload *encrypted_key_alloc(struct key *key, | |
525 | const char *master_desc, | |
526 | const char *datalen) | |
527 | { | |
528 | struct encrypted_key_payload *epayload = NULL; | |
529 | unsigned short datablob_len; | |
530 | unsigned short decrypted_datalen; | |
531 | unsigned int encrypted_datalen; | |
532 | long dlen; | |
533 | int ret; | |
534 | ||
535 | ret = strict_strtol(datalen, 10, &dlen); | |
536 | if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE) | |
537 | return ERR_PTR(-EINVAL); | |
538 | ||
539 | decrypted_datalen = dlen; | |
540 | encrypted_datalen = roundup(decrypted_datalen, blksize); | |
541 | ||
542 | datablob_len = strlen(master_desc) + 1 + strlen(datalen) + 1 | |
543 | + ivsize + 1 + encrypted_datalen; | |
544 | ||
545 | ret = key_payload_reserve(key, decrypted_datalen + datablob_len | |
546 | + HASH_SIZE + 1); | |
547 | if (ret < 0) | |
548 | return ERR_PTR(ret); | |
549 | ||
550 | epayload = kzalloc(sizeof(*epayload) + decrypted_datalen + | |
551 | datablob_len + HASH_SIZE + 1, GFP_KERNEL); | |
552 | if (!epayload) | |
553 | return ERR_PTR(-ENOMEM); | |
554 | ||
555 | epayload->decrypted_datalen = decrypted_datalen; | |
556 | epayload->datablob_len = datablob_len; | |
557 | return epayload; | |
558 | } | |
559 | ||
560 | static int encrypted_key_decrypt(struct encrypted_key_payload *epayload, | |
561 | const char *hex_encoded_iv, | |
562 | const char *hex_encoded_data) | |
563 | { | |
564 | struct key *mkey; | |
565 | u8 derived_key[HASH_SIZE]; | |
566 | u8 *master_key; | |
567 | u8 *hmac; | |
568 | unsigned int master_keylen; | |
569 | unsigned int encrypted_datalen; | |
570 | int ret; | |
571 | ||
572 | encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); | |
573 | hex2bin(epayload->iv, hex_encoded_iv, ivsize); | |
574 | hex2bin(epayload->encrypted_data, hex_encoded_data, encrypted_datalen); | |
575 | ||
576 | hmac = epayload->master_desc + epayload->datablob_len; | |
577 | hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2), HASH_SIZE); | |
578 | ||
579 | mkey = request_master_key(epayload, &master_key, &master_keylen); | |
580 | if (IS_ERR(mkey)) | |
581 | return PTR_ERR(mkey); | |
582 | ||
583 | ret = datablob_hmac_verify(epayload, master_key, master_keylen); | |
584 | if (ret < 0) { | |
585 | pr_err("encrypted_key: bad hmac (%d)\n", ret); | |
586 | goto out; | |
587 | } | |
588 | ||
589 | ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); | |
590 | if (ret < 0) | |
591 | goto out; | |
592 | ||
593 | ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key); | |
594 | if (ret < 0) | |
595 | pr_err("encrypted_key: failed to decrypt key (%d)\n", ret); | |
596 | out: | |
597 | up_read(&mkey->sem); | |
598 | key_put(mkey); | |
599 | return ret; | |
600 | } | |
601 | ||
602 | static void __ekey_init(struct encrypted_key_payload *epayload, | |
603 | const char *master_desc, const char *datalen) | |
604 | { | |
605 | epayload->master_desc = epayload->decrypted_data | |
606 | + epayload->decrypted_datalen; | |
607 | epayload->datalen = epayload->master_desc + strlen(master_desc) + 1; | |
608 | epayload->iv = epayload->datalen + strlen(datalen) + 1; | |
609 | epayload->encrypted_data = epayload->iv + ivsize + 1; | |
610 | ||
611 | memcpy(epayload->master_desc, master_desc, strlen(master_desc)); | |
612 | memcpy(epayload->datalen, datalen, strlen(datalen)); | |
613 | } | |
614 | ||
615 | /* | |
616 | * encrypted_init - initialize an encrypted key | |
617 | * | |
618 | * For a new key, use a random number for both the iv and data | |
619 | * itself. For an old key, decrypt the hex encoded data. | |
620 | */ | |
621 | static int encrypted_init(struct encrypted_key_payload *epayload, | |
622 | const char *master_desc, const char *datalen, | |
623 | const char *hex_encoded_iv, | |
624 | const char *hex_encoded_data) | |
625 | { | |
626 | int ret = 0; | |
627 | ||
628 | __ekey_init(epayload, master_desc, datalen); | |
629 | if (!hex_encoded_data) { | |
630 | get_random_bytes(epayload->iv, ivsize); | |
631 | ||
632 | get_random_bytes(epayload->decrypted_data, | |
633 | epayload->decrypted_datalen); | |
634 | } else | |
635 | ret = encrypted_key_decrypt(epayload, hex_encoded_iv, | |
636 | hex_encoded_data); | |
637 | return ret; | |
638 | } | |
639 | ||
640 | /* | |
641 | * encrypted_instantiate - instantiate an encrypted key | |
642 | * | |
643 | * Decrypt an existing encrypted datablob or create a new encrypted key | |
644 | * based on a kernel random number. | |
645 | * | |
646 | * On success, return 0. Otherwise return errno. | |
647 | */ | |
648 | static int encrypted_instantiate(struct key *key, const void *data, | |
649 | size_t datalen) | |
650 | { | |
651 | struct encrypted_key_payload *epayload = NULL; | |
652 | char *datablob = NULL; | |
653 | char *master_desc = NULL; | |
654 | char *decrypted_datalen = NULL; | |
655 | char *hex_encoded_iv = NULL; | |
656 | char *hex_encoded_data = NULL; | |
657 | int ret; | |
658 | ||
659 | if (datalen <= 0 || datalen > 32767 || !data) | |
660 | return -EINVAL; | |
661 | ||
662 | datablob = kmalloc(datalen + 1, GFP_KERNEL); | |
663 | if (!datablob) | |
664 | return -ENOMEM; | |
665 | datablob[datalen] = 0; | |
666 | memcpy(datablob, data, datalen); | |
667 | ret = datablob_parse(datablob, &master_desc, &decrypted_datalen, | |
668 | &hex_encoded_iv, &hex_encoded_data); | |
669 | if (ret < 0) | |
670 | goto out; | |
671 | ||
672 | epayload = encrypted_key_alloc(key, master_desc, decrypted_datalen); | |
673 | if (IS_ERR(epayload)) { | |
674 | ret = PTR_ERR(epayload); | |
675 | goto out; | |
676 | } | |
677 | ret = encrypted_init(epayload, master_desc, decrypted_datalen, | |
678 | hex_encoded_iv, hex_encoded_data); | |
679 | if (ret < 0) { | |
680 | kfree(epayload); | |
681 | goto out; | |
682 | } | |
683 | ||
684 | rcu_assign_pointer(key->payload.data, epayload); | |
685 | out: | |
686 | kfree(datablob); | |
687 | return ret; | |
688 | } | |
689 | ||
690 | static void encrypted_rcu_free(struct rcu_head *rcu) | |
691 | { | |
692 | struct encrypted_key_payload *epayload; | |
693 | ||
694 | epayload = container_of(rcu, struct encrypted_key_payload, rcu); | |
695 | memset(epayload->decrypted_data, 0, epayload->decrypted_datalen); | |
696 | kfree(epayload); | |
697 | } | |
698 | ||
699 | /* | |
700 | * encrypted_update - update the master key description | |
701 | * | |
702 | * Change the master key description for an existing encrypted key. | |
703 | * The next read will return an encrypted datablob using the new | |
704 | * master key description. | |
705 | * | |
706 | * On success, return 0. Otherwise return errno. | |
707 | */ | |
708 | static int encrypted_update(struct key *key, const void *data, size_t datalen) | |
709 | { | |
710 | struct encrypted_key_payload *epayload = key->payload.data; | |
711 | struct encrypted_key_payload *new_epayload; | |
712 | char *buf; | |
713 | char *new_master_desc = NULL; | |
714 | int ret = 0; | |
715 | ||
716 | if (datalen <= 0 || datalen > 32767 || !data) | |
717 | return -EINVAL; | |
718 | ||
719 | buf = kmalloc(datalen + 1, GFP_KERNEL); | |
720 | if (!buf) | |
721 | return -ENOMEM; | |
722 | ||
723 | buf[datalen] = 0; | |
724 | memcpy(buf, data, datalen); | |
725 | ret = datablob_parse(buf, &new_master_desc, NULL, NULL, NULL); | |
726 | if (ret < 0) | |
727 | goto out; | |
728 | ||
729 | ret = valid_master_desc(new_master_desc, epayload->master_desc); | |
730 | if (ret < 0) | |
731 | goto out; | |
732 | ||
733 | new_epayload = encrypted_key_alloc(key, new_master_desc, | |
734 | epayload->datalen); | |
735 | if (IS_ERR(new_epayload)) { | |
736 | ret = PTR_ERR(new_epayload); | |
737 | goto out; | |
738 | } | |
739 | ||
740 | __ekey_init(new_epayload, new_master_desc, epayload->datalen); | |
741 | ||
742 | memcpy(new_epayload->iv, epayload->iv, ivsize); | |
743 | memcpy(new_epayload->decrypted_data, epayload->decrypted_data, | |
744 | epayload->decrypted_datalen); | |
745 | ||
746 | rcu_assign_pointer(key->payload.data, new_epayload); | |
747 | call_rcu(&epayload->rcu, encrypted_rcu_free); | |
748 | out: | |
749 | kfree(buf); | |
750 | return ret; | |
751 | } | |
752 | ||
753 | /* | |
754 | * encrypted_read - format and copy the encrypted data to userspace | |
755 | * | |
756 | * The resulting datablob format is: | |
757 | * <master-key name> <decrypted data length> <encrypted iv> <encrypted data> | |
758 | * | |
759 | * On success, return to userspace the encrypted key datablob size. | |
760 | */ | |
761 | static long encrypted_read(const struct key *key, char __user *buffer, | |
762 | size_t buflen) | |
763 | { | |
764 | struct encrypted_key_payload *epayload; | |
765 | struct key *mkey; | |
766 | u8 *master_key; | |
767 | unsigned int master_keylen; | |
768 | char derived_key[HASH_SIZE]; | |
769 | char *ascii_buf; | |
770 | size_t asciiblob_len; | |
771 | int ret; | |
772 | ||
773 | epayload = rcu_dereference_protected(key->payload.data, | |
774 | rwsem_is_locked(&((struct key *)key)->sem)); | |
775 | ||
776 | /* returns the hex encoded iv, encrypted-data, and hmac as ascii */ | |
777 | asciiblob_len = epayload->datablob_len + ivsize + 1 | |
778 | + roundup(epayload->decrypted_datalen, blksize) | |
779 | + (HASH_SIZE * 2); | |
780 | ||
781 | if (!buffer || buflen < asciiblob_len) | |
782 | return asciiblob_len; | |
783 | ||
784 | mkey = request_master_key(epayload, &master_key, &master_keylen); | |
785 | if (IS_ERR(mkey)) | |
786 | return PTR_ERR(mkey); | |
787 | ||
788 | ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); | |
789 | if (ret < 0) | |
790 | goto out; | |
791 | ||
792 | ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key); | |
793 | if (ret < 0) | |
794 | goto out; | |
795 | ||
796 | ret = datablob_hmac_append(epayload, master_key, master_keylen); | |
797 | if (ret < 0) | |
798 | goto out; | |
799 | ||
800 | ascii_buf = datablob_format(epayload, asciiblob_len); | |
801 | if (!ascii_buf) { | |
802 | ret = -ENOMEM; | |
803 | goto out; | |
804 | } | |
805 | ||
806 | up_read(&mkey->sem); | |
807 | key_put(mkey); | |
808 | ||
809 | if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0) | |
810 | ret = -EFAULT; | |
811 | kfree(ascii_buf); | |
812 | ||
813 | return asciiblob_len; | |
814 | out: | |
815 | up_read(&mkey->sem); | |
816 | key_put(mkey); | |
817 | return ret; | |
818 | } | |
819 | ||
820 | /* | |
821 | * encrypted_destroy - before freeing the key, clear the decrypted data | |
822 | * | |
823 | * Before freeing the key, clear the memory containing the decrypted | |
824 | * key data. | |
825 | */ | |
826 | static void encrypted_destroy(struct key *key) | |
827 | { | |
828 | struct encrypted_key_payload *epayload = key->payload.data; | |
829 | ||
830 | if (!epayload) | |
831 | return; | |
832 | ||
833 | memset(epayload->decrypted_data, 0, epayload->decrypted_datalen); | |
834 | kfree(key->payload.data); | |
835 | } | |
836 | ||
837 | struct key_type key_type_encrypted = { | |
838 | .name = "encrypted", | |
839 | .instantiate = encrypted_instantiate, | |
840 | .update = encrypted_update, | |
841 | .match = user_match, | |
842 | .destroy = encrypted_destroy, | |
843 | .describe = user_describe, | |
844 | .read = encrypted_read, | |
845 | }; | |
846 | EXPORT_SYMBOL_GPL(key_type_encrypted); | |
847 | ||
848 | static void encrypted_shash_release(void) | |
849 | { | |
850 | if (hashalg) | |
851 | crypto_free_shash(hashalg); | |
852 | if (hmacalg) | |
853 | crypto_free_shash(hmacalg); | |
854 | } | |
855 | ||
856 | static int __init encrypted_shash_alloc(void) | |
857 | { | |
858 | int ret; | |
859 | ||
860 | hmacalg = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC); | |
861 | if (IS_ERR(hmacalg)) { | |
862 | pr_info("encrypted_key: could not allocate crypto %s\n", | |
863 | hmac_alg); | |
864 | return PTR_ERR(hmacalg); | |
865 | } | |
866 | ||
867 | hashalg = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC); | |
868 | if (IS_ERR(hashalg)) { | |
869 | pr_info("encrypted_key: could not allocate crypto %s\n", | |
870 | hash_alg); | |
871 | ret = PTR_ERR(hashalg); | |
872 | goto hashalg_fail; | |
873 | } | |
874 | ||
875 | return 0; | |
876 | ||
877 | hashalg_fail: | |
878 | crypto_free_shash(hmacalg); | |
879 | return ret; | |
880 | } | |
881 | ||
882 | static int __init init_encrypted(void) | |
883 | { | |
884 | int ret; | |
885 | ||
886 | ret = encrypted_shash_alloc(); | |
887 | if (ret < 0) | |
888 | return ret; | |
889 | ret = register_key_type(&key_type_encrypted); | |
890 | if (ret < 0) | |
891 | goto out; | |
892 | return aes_get_sizes(); | |
893 | out: | |
894 | encrypted_shash_release(); | |
895 | return ret; | |
896 | ||
897 | } | |
898 | ||
899 | static void __exit cleanup_encrypted(void) | |
900 | { | |
901 | encrypted_shash_release(); | |
902 | unregister_key_type(&key_type_encrypted); | |
903 | } | |
904 | ||
905 | late_initcall(init_encrypted); | |
906 | module_exit(cleanup_encrypted); | |
907 | ||
908 | MODULE_LICENSE("GPL"); |