Commit | Line | Data |
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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 | * | |
d410fa4e | 11 | * See Documentation/security/keys-trusted-encrypted.txt |
7e70cb49 MZ |
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 | ||
b9703449 | 33 | #include "encrypted.h" |
7e70cb49 | 34 | |
3b1826ce MZ |
35 | static const char KEY_TRUSTED_PREFIX[] = "trusted:"; |
36 | static const char KEY_USER_PREFIX[] = "user:"; | |
7e70cb49 MZ |
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 | ||
3b1826ce MZ |
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 | ||
7e70cb49 MZ |
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 | * | |
08fa2aa5 | 87 | * key-type:= "trusted:" | "user:" |
7e70cb49 MZ |
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, | |
1f35065a | 131 | char **decrypted_datalen, char **hex_encoded_iv) |
7e70cb49 MZ |
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; | |
7e70cb49 MZ |
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, | |
3b1826ce | 219 | u8 **master_key, size_t *master_keylen) |
7e70cb49 MZ |
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, | |
3b1826ce | 242 | size_t *master_keylen) |
7e70cb49 MZ |
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 | ||
3b1826ce | 259 | static struct sdesc *alloc_sdesc(struct crypto_shash *alg) |
7e70cb49 MZ |
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 | ||
3b1826ce MZ |
273 | static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen, |
274 | const u8 *buf, unsigned int buflen) | |
7e70cb49 MZ |
275 | { |
276 | struct sdesc *sdesc; | |
277 | int ret; | |
278 | ||
3b1826ce | 279 | sdesc = alloc_sdesc(hmacalg); |
7e70cb49 MZ |
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 | ||
3b1826ce | 292 | static int calc_hash(u8 *digest, const u8 *buf, unsigned int buflen) |
7e70cb49 MZ |
293 | { |
294 | struct sdesc *sdesc; | |
295 | int ret; | |
296 | ||
3b1826ce | 297 | sdesc = alloc_sdesc(hashalg); |
7e70cb49 MZ |
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, | |
3b1826ce | 312 | const u8 *master_key, size_t master_keylen) |
7e70cb49 MZ |
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, | |
3b1826ce MZ |
340 | unsigned int key_len, const u8 *iv, |
341 | unsigned int ivsize) | |
7e70cb49 MZ |
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, | |
3b1826ce | 364 | u8 **master_key, size_t *master_keylen) |
7e70cb49 MZ |
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 | ||
f91c2c5c | 381 | if (IS_ERR(mkey)) { |
7e70cb49 MZ |
382 | pr_info("encrypted_key: key %s not found", |
383 | epayload->master_desc); | |
f91c2c5c RS |
384 | goto out; |
385 | } | |
386 | ||
387 | dump_master_key(*master_key, *master_keylen); | |
7e70cb49 MZ |
388 | out: |
389 | return mkey; | |
390 | } | |
391 | ||
392 | /* Before returning data to userspace, encrypt decrypted data. */ | |
393 | static int derived_key_encrypt(struct encrypted_key_payload *epayload, | |
394 | const u8 *derived_key, | |
3b1826ce | 395 | unsigned int derived_keylen) |
7e70cb49 MZ |
396 | { |
397 | struct scatterlist sg_in[2]; | |
398 | struct scatterlist sg_out[1]; | |
399 | struct blkcipher_desc desc; | |
400 | unsigned int encrypted_datalen; | |
401 | unsigned int padlen; | |
402 | char pad[16]; | |
403 | int ret; | |
404 | ||
405 | encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); | |
406 | padlen = encrypted_datalen - epayload->decrypted_datalen; | |
407 | ||
408 | ret = init_blkcipher_desc(&desc, derived_key, derived_keylen, | |
409 | epayload->iv, ivsize); | |
410 | if (ret < 0) | |
411 | goto out; | |
412 | dump_decrypted_data(epayload); | |
413 | ||
414 | memset(pad, 0, sizeof pad); | |
415 | sg_init_table(sg_in, 2); | |
416 | sg_set_buf(&sg_in[0], epayload->decrypted_data, | |
417 | epayload->decrypted_datalen); | |
418 | sg_set_buf(&sg_in[1], pad, padlen); | |
419 | ||
420 | sg_init_table(sg_out, 1); | |
421 | sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen); | |
422 | ||
423 | ret = crypto_blkcipher_encrypt(&desc, sg_out, sg_in, encrypted_datalen); | |
424 | crypto_free_blkcipher(desc.tfm); | |
425 | if (ret < 0) | |
426 | pr_err("encrypted_key: failed to encrypt (%d)\n", ret); | |
427 | else | |
428 | dump_encrypted_data(epayload, encrypted_datalen); | |
429 | out: | |
430 | return ret; | |
431 | } | |
432 | ||
433 | static int datablob_hmac_append(struct encrypted_key_payload *epayload, | |
3b1826ce | 434 | const u8 *master_key, size_t master_keylen) |
7e70cb49 MZ |
435 | { |
436 | u8 derived_key[HASH_SIZE]; | |
437 | u8 *digest; | |
438 | int ret; | |
439 | ||
440 | ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); | |
441 | if (ret < 0) | |
442 | goto out; | |
443 | ||
444 | digest = epayload->master_desc + epayload->datablob_len; | |
445 | ret = calc_hmac(digest, derived_key, sizeof derived_key, | |
446 | epayload->master_desc, epayload->datablob_len); | |
447 | if (!ret) | |
448 | dump_hmac(NULL, digest, HASH_SIZE); | |
449 | out: | |
450 | return ret; | |
451 | } | |
452 | ||
453 | /* verify HMAC before decrypting encrypted key */ | |
454 | static int datablob_hmac_verify(struct encrypted_key_payload *epayload, | |
3b1826ce | 455 | const u8 *master_key, size_t master_keylen) |
7e70cb49 MZ |
456 | { |
457 | u8 derived_key[HASH_SIZE]; | |
458 | u8 digest[HASH_SIZE]; | |
459 | int ret; | |
460 | ||
461 | ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); | |
462 | if (ret < 0) | |
463 | goto out; | |
464 | ||
465 | ret = calc_hmac(digest, derived_key, sizeof derived_key, | |
466 | epayload->master_desc, epayload->datablob_len); | |
467 | if (ret < 0) | |
468 | goto out; | |
469 | ret = memcmp(digest, epayload->master_desc + epayload->datablob_len, | |
470 | sizeof digest); | |
471 | if (ret) { | |
472 | ret = -EINVAL; | |
473 | dump_hmac("datablob", | |
474 | epayload->master_desc + epayload->datablob_len, | |
475 | HASH_SIZE); | |
476 | dump_hmac("calc", digest, HASH_SIZE); | |
477 | } | |
478 | out: | |
479 | return ret; | |
480 | } | |
481 | ||
482 | static int derived_key_decrypt(struct encrypted_key_payload *epayload, | |
483 | const u8 *derived_key, | |
3b1826ce | 484 | unsigned int derived_keylen) |
7e70cb49 MZ |
485 | { |
486 | struct scatterlist sg_in[1]; | |
487 | struct scatterlist sg_out[2]; | |
488 | struct blkcipher_desc desc; | |
489 | unsigned int encrypted_datalen; | |
490 | char pad[16]; | |
491 | int ret; | |
492 | ||
493 | encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); | |
494 | ret = init_blkcipher_desc(&desc, derived_key, derived_keylen, | |
495 | epayload->iv, ivsize); | |
496 | if (ret < 0) | |
497 | goto out; | |
498 | dump_encrypted_data(epayload, encrypted_datalen); | |
499 | ||
500 | memset(pad, 0, sizeof pad); | |
501 | sg_init_table(sg_in, 1); | |
502 | sg_init_table(sg_out, 2); | |
503 | sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen); | |
504 | sg_set_buf(&sg_out[0], epayload->decrypted_data, | |
3b1826ce | 505 | epayload->decrypted_datalen); |
7e70cb49 MZ |
506 | sg_set_buf(&sg_out[1], pad, sizeof pad); |
507 | ||
508 | ret = crypto_blkcipher_decrypt(&desc, sg_out, sg_in, encrypted_datalen); | |
509 | crypto_free_blkcipher(desc.tfm); | |
510 | if (ret < 0) | |
511 | goto out; | |
512 | dump_decrypted_data(epayload); | |
513 | out: | |
514 | return ret; | |
515 | } | |
516 | ||
517 | /* Allocate memory for decrypted key and datablob. */ | |
518 | static struct encrypted_key_payload *encrypted_key_alloc(struct key *key, | |
519 | const char *master_desc, | |
520 | const char *datalen) | |
521 | { | |
522 | struct encrypted_key_payload *epayload = NULL; | |
523 | unsigned short datablob_len; | |
524 | unsigned short decrypted_datalen; | |
525 | unsigned int encrypted_datalen; | |
526 | long dlen; | |
527 | int ret; | |
528 | ||
529 | ret = strict_strtol(datalen, 10, &dlen); | |
530 | if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE) | |
531 | return ERR_PTR(-EINVAL); | |
532 | ||
533 | decrypted_datalen = dlen; | |
534 | encrypted_datalen = roundup(decrypted_datalen, blksize); | |
535 | ||
536 | datablob_len = strlen(master_desc) + 1 + strlen(datalen) + 1 | |
537 | + ivsize + 1 + encrypted_datalen; | |
538 | ||
539 | ret = key_payload_reserve(key, decrypted_datalen + datablob_len | |
540 | + HASH_SIZE + 1); | |
541 | if (ret < 0) | |
542 | return ERR_PTR(ret); | |
543 | ||
544 | epayload = kzalloc(sizeof(*epayload) + decrypted_datalen + | |
545 | datablob_len + HASH_SIZE + 1, GFP_KERNEL); | |
546 | if (!epayload) | |
547 | return ERR_PTR(-ENOMEM); | |
548 | ||
549 | epayload->decrypted_datalen = decrypted_datalen; | |
550 | epayload->datablob_len = datablob_len; | |
551 | return epayload; | |
552 | } | |
553 | ||
554 | static int encrypted_key_decrypt(struct encrypted_key_payload *epayload, | |
1f35065a | 555 | const char *hex_encoded_iv) |
7e70cb49 MZ |
556 | { |
557 | struct key *mkey; | |
558 | u8 derived_key[HASH_SIZE]; | |
559 | u8 *master_key; | |
560 | u8 *hmac; | |
1f35065a | 561 | const char *hex_encoded_data; |
7e70cb49 | 562 | unsigned int encrypted_datalen; |
3b1826ce | 563 | size_t master_keylen; |
1f35065a | 564 | size_t asciilen; |
7e70cb49 MZ |
565 | int ret; |
566 | ||
567 | encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); | |
1f35065a MZ |
568 | asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2; |
569 | if (strlen(hex_encoded_iv) != asciilen) | |
570 | return -EINVAL; | |
571 | ||
572 | hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2; | |
7e70cb49 MZ |
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, | |
1f35065a | 623 | const char *hex_encoded_iv) |
7e70cb49 MZ |
624 | { |
625 | int ret = 0; | |
626 | ||
627 | __ekey_init(epayload, master_desc, datalen); | |
1f35065a | 628 | if (!hex_encoded_iv) { |
7e70cb49 MZ |
629 | get_random_bytes(epayload->iv, ivsize); |
630 | ||
631 | get_random_bytes(epayload->decrypted_data, | |
632 | epayload->decrypted_datalen); | |
633 | } else | |
1f35065a | 634 | ret = encrypted_key_decrypt(epayload, hex_encoded_iv); |
7e70cb49 MZ |
635 | return ret; |
636 | } | |
637 | ||
638 | /* | |
639 | * encrypted_instantiate - instantiate an encrypted key | |
640 | * | |
641 | * Decrypt an existing encrypted datablob or create a new encrypted key | |
642 | * based on a kernel random number. | |
643 | * | |
644 | * On success, return 0. Otherwise return errno. | |
645 | */ | |
646 | static int encrypted_instantiate(struct key *key, const void *data, | |
647 | size_t datalen) | |
648 | { | |
649 | struct encrypted_key_payload *epayload = NULL; | |
650 | char *datablob = NULL; | |
651 | char *master_desc = NULL; | |
652 | char *decrypted_datalen = NULL; | |
653 | char *hex_encoded_iv = NULL; | |
7e70cb49 MZ |
654 | int ret; |
655 | ||
656 | if (datalen <= 0 || datalen > 32767 || !data) | |
657 | return -EINVAL; | |
658 | ||
659 | datablob = kmalloc(datalen + 1, GFP_KERNEL); | |
660 | if (!datablob) | |
661 | return -ENOMEM; | |
662 | datablob[datalen] = 0; | |
663 | memcpy(datablob, data, datalen); | |
664 | ret = datablob_parse(datablob, &master_desc, &decrypted_datalen, | |
1f35065a | 665 | &hex_encoded_iv); |
7e70cb49 MZ |
666 | if (ret < 0) |
667 | goto out; | |
668 | ||
669 | epayload = encrypted_key_alloc(key, master_desc, decrypted_datalen); | |
670 | if (IS_ERR(epayload)) { | |
671 | ret = PTR_ERR(epayload); | |
672 | goto out; | |
673 | } | |
674 | ret = encrypted_init(epayload, master_desc, decrypted_datalen, | |
1f35065a | 675 | hex_encoded_iv); |
7e70cb49 MZ |
676 | if (ret < 0) { |
677 | kfree(epayload); | |
678 | goto out; | |
679 | } | |
680 | ||
681 | rcu_assign_pointer(key->payload.data, epayload); | |
682 | out: | |
683 | kfree(datablob); | |
684 | return ret; | |
685 | } | |
686 | ||
687 | static void encrypted_rcu_free(struct rcu_head *rcu) | |
688 | { | |
689 | struct encrypted_key_payload *epayload; | |
690 | ||
691 | epayload = container_of(rcu, struct encrypted_key_payload, rcu); | |
692 | memset(epayload->decrypted_data, 0, epayload->decrypted_datalen); | |
693 | kfree(epayload); | |
694 | } | |
695 | ||
696 | /* | |
697 | * encrypted_update - update the master key description | |
698 | * | |
699 | * Change the master key description for an existing encrypted key. | |
700 | * The next read will return an encrypted datablob using the new | |
701 | * master key description. | |
702 | * | |
703 | * On success, return 0. Otherwise return errno. | |
704 | */ | |
705 | static int encrypted_update(struct key *key, const void *data, size_t datalen) | |
706 | { | |
707 | struct encrypted_key_payload *epayload = key->payload.data; | |
708 | struct encrypted_key_payload *new_epayload; | |
709 | char *buf; | |
710 | char *new_master_desc = NULL; | |
711 | int ret = 0; | |
712 | ||
713 | if (datalen <= 0 || datalen > 32767 || !data) | |
714 | return -EINVAL; | |
715 | ||
716 | buf = kmalloc(datalen + 1, GFP_KERNEL); | |
717 | if (!buf) | |
718 | return -ENOMEM; | |
719 | ||
720 | buf[datalen] = 0; | |
721 | memcpy(buf, data, datalen); | |
1f35065a | 722 | ret = datablob_parse(buf, &new_master_desc, NULL, NULL); |
7e70cb49 MZ |
723 | if (ret < 0) |
724 | goto out; | |
725 | ||
726 | ret = valid_master_desc(new_master_desc, epayload->master_desc); | |
727 | if (ret < 0) | |
728 | goto out; | |
729 | ||
730 | new_epayload = encrypted_key_alloc(key, new_master_desc, | |
731 | epayload->datalen); | |
732 | if (IS_ERR(new_epayload)) { | |
733 | ret = PTR_ERR(new_epayload); | |
734 | goto out; | |
735 | } | |
736 | ||
737 | __ekey_init(new_epayload, new_master_desc, epayload->datalen); | |
738 | ||
739 | memcpy(new_epayload->iv, epayload->iv, ivsize); | |
740 | memcpy(new_epayload->decrypted_data, epayload->decrypted_data, | |
741 | epayload->decrypted_datalen); | |
742 | ||
743 | rcu_assign_pointer(key->payload.data, new_epayload); | |
744 | call_rcu(&epayload->rcu, encrypted_rcu_free); | |
745 | out: | |
746 | kfree(buf); | |
747 | return ret; | |
748 | } | |
749 | ||
750 | /* | |
751 | * encrypted_read - format and copy the encrypted data to userspace | |
752 | * | |
753 | * The resulting datablob format is: | |
754 | * <master-key name> <decrypted data length> <encrypted iv> <encrypted data> | |
755 | * | |
756 | * On success, return to userspace the encrypted key datablob size. | |
757 | */ | |
758 | static long encrypted_read(const struct key *key, char __user *buffer, | |
759 | size_t buflen) | |
760 | { | |
761 | struct encrypted_key_payload *epayload; | |
762 | struct key *mkey; | |
763 | u8 *master_key; | |
3b1826ce | 764 | size_t master_keylen; |
7e70cb49 MZ |
765 | char derived_key[HASH_SIZE]; |
766 | char *ascii_buf; | |
767 | size_t asciiblob_len; | |
768 | int ret; | |
769 | ||
633e804e | 770 | epayload = rcu_dereference_key(key); |
7e70cb49 MZ |
771 | |
772 | /* returns the hex encoded iv, encrypted-data, and hmac as ascii */ | |
773 | asciiblob_len = epayload->datablob_len + ivsize + 1 | |
774 | + roundup(epayload->decrypted_datalen, blksize) | |
775 | + (HASH_SIZE * 2); | |
776 | ||
777 | if (!buffer || buflen < asciiblob_len) | |
778 | return asciiblob_len; | |
779 | ||
780 | mkey = request_master_key(epayload, &master_key, &master_keylen); | |
781 | if (IS_ERR(mkey)) | |
782 | return PTR_ERR(mkey); | |
783 | ||
784 | ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); | |
785 | if (ret < 0) | |
786 | goto out; | |
787 | ||
788 | ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key); | |
789 | if (ret < 0) | |
790 | goto out; | |
791 | ||
792 | ret = datablob_hmac_append(epayload, master_key, master_keylen); | |
793 | if (ret < 0) | |
794 | goto out; | |
795 | ||
796 | ascii_buf = datablob_format(epayload, asciiblob_len); | |
797 | if (!ascii_buf) { | |
798 | ret = -ENOMEM; | |
799 | goto out; | |
800 | } | |
801 | ||
802 | up_read(&mkey->sem); | |
803 | key_put(mkey); | |
804 | ||
805 | if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0) | |
806 | ret = -EFAULT; | |
807 | kfree(ascii_buf); | |
808 | ||
809 | return asciiblob_len; | |
810 | out: | |
811 | up_read(&mkey->sem); | |
812 | key_put(mkey); | |
813 | return ret; | |
814 | } | |
815 | ||
816 | /* | |
817 | * encrypted_destroy - before freeing the key, clear the decrypted data | |
818 | * | |
819 | * Before freeing the key, clear the memory containing the decrypted | |
820 | * key data. | |
821 | */ | |
822 | static void encrypted_destroy(struct key *key) | |
823 | { | |
824 | struct encrypted_key_payload *epayload = key->payload.data; | |
825 | ||
826 | if (!epayload) | |
827 | return; | |
828 | ||
829 | memset(epayload->decrypted_data, 0, epayload->decrypted_datalen); | |
830 | kfree(key->payload.data); | |
831 | } | |
832 | ||
833 | struct key_type key_type_encrypted = { | |
834 | .name = "encrypted", | |
835 | .instantiate = encrypted_instantiate, | |
836 | .update = encrypted_update, | |
837 | .match = user_match, | |
838 | .destroy = encrypted_destroy, | |
839 | .describe = user_describe, | |
840 | .read = encrypted_read, | |
841 | }; | |
842 | EXPORT_SYMBOL_GPL(key_type_encrypted); | |
843 | ||
844 | static void encrypted_shash_release(void) | |
845 | { | |
846 | if (hashalg) | |
847 | crypto_free_shash(hashalg); | |
848 | if (hmacalg) | |
849 | crypto_free_shash(hmacalg); | |
850 | } | |
851 | ||
852 | static int __init encrypted_shash_alloc(void) | |
853 | { | |
854 | int ret; | |
855 | ||
856 | hmacalg = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC); | |
857 | if (IS_ERR(hmacalg)) { | |
858 | pr_info("encrypted_key: could not allocate crypto %s\n", | |
859 | hmac_alg); | |
860 | return PTR_ERR(hmacalg); | |
861 | } | |
862 | ||
863 | hashalg = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC); | |
864 | if (IS_ERR(hashalg)) { | |
865 | pr_info("encrypted_key: could not allocate crypto %s\n", | |
866 | hash_alg); | |
867 | ret = PTR_ERR(hashalg); | |
868 | goto hashalg_fail; | |
869 | } | |
870 | ||
871 | return 0; | |
872 | ||
873 | hashalg_fail: | |
874 | crypto_free_shash(hmacalg); | |
875 | return ret; | |
876 | } | |
877 | ||
878 | static int __init init_encrypted(void) | |
879 | { | |
880 | int ret; | |
881 | ||
882 | ret = encrypted_shash_alloc(); | |
883 | if (ret < 0) | |
884 | return ret; | |
885 | ret = register_key_type(&key_type_encrypted); | |
886 | if (ret < 0) | |
887 | goto out; | |
888 | return aes_get_sizes(); | |
889 | out: | |
890 | encrypted_shash_release(); | |
891 | return ret; | |
b9703449 | 892 | |
7e70cb49 MZ |
893 | } |
894 | ||
895 | static void __exit cleanup_encrypted(void) | |
896 | { | |
897 | encrypted_shash_release(); | |
898 | unregister_key_type(&key_type_encrypted); | |
899 | } | |
900 | ||
901 | late_initcall(init_encrypted); | |
902 | module_exit(cleanup_encrypted); | |
903 | ||
904 | MODULE_LICENSE("GPL"); |