Commit | Line | Data |
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7e70cb49 MZ |
1 | /* |
2 | * Copyright (C) 2010 IBM Corporation | |
4e561d38 RS |
3 | * Copyright (C) 2010 Politecnico di Torino, Italy |
4 | * TORSEC group -- http://security.polito.it | |
7e70cb49 | 5 | * |
4e561d38 | 6 | * Authors: |
7e70cb49 | 7 | * Mimi Zohar <zohar@us.ibm.com> |
4e561d38 | 8 | * Roberto Sassu <roberto.sassu@polito.it> |
7e70cb49 MZ |
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 | * | |
d410fa4e | 14 | * See Documentation/security/keys-trusted-encrypted.txt |
7e70cb49 MZ |
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> | |
93ae86e7 | 23 | #include <linux/err.h> |
7e70cb49 MZ |
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/crypto.h> | |
79a73d18 | 32 | #include <linux/ctype.h> |
7e70cb49 MZ |
33 | #include <crypto/hash.h> |
34 | #include <crypto/sha.h> | |
35 | #include <crypto/aes.h> | |
36 | ||
b9703449 | 37 | #include "encrypted.h" |
79a73d18 | 38 | #include "ecryptfs_format.h" |
7e70cb49 | 39 | |
3b1826ce MZ |
40 | static const char KEY_TRUSTED_PREFIX[] = "trusted:"; |
41 | static const char KEY_USER_PREFIX[] = "user:"; | |
7e70cb49 MZ |
42 | static const char hash_alg[] = "sha256"; |
43 | static const char hmac_alg[] = "hmac(sha256)"; | |
44 | static const char blkcipher_alg[] = "cbc(aes)"; | |
4e561d38 | 45 | static const char key_format_default[] = "default"; |
79a73d18 | 46 | static const char key_format_ecryptfs[] = "ecryptfs"; |
7e70cb49 MZ |
47 | static unsigned int ivsize; |
48 | static int blksize; | |
49 | ||
3b1826ce MZ |
50 | #define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1) |
51 | #define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1) | |
79a73d18 | 52 | #define KEY_ECRYPTFS_DESC_LEN 16 |
3b1826ce MZ |
53 | #define HASH_SIZE SHA256_DIGEST_SIZE |
54 | #define MAX_DATA_SIZE 4096 | |
55 | #define MIN_DATA_SIZE 20 | |
56 | ||
7e70cb49 MZ |
57 | struct sdesc { |
58 | struct shash_desc shash; | |
59 | char ctx[]; | |
60 | }; | |
61 | ||
62 | static struct crypto_shash *hashalg; | |
63 | static struct crypto_shash *hmacalg; | |
64 | ||
65 | enum { | |
66 | Opt_err = -1, Opt_new, Opt_load, Opt_update | |
67 | }; | |
68 | ||
4e561d38 | 69 | enum { |
79a73d18 | 70 | Opt_error = -1, Opt_default, Opt_ecryptfs |
4e561d38 RS |
71 | }; |
72 | ||
73 | static const match_table_t key_format_tokens = { | |
74 | {Opt_default, "default"}, | |
79a73d18 | 75 | {Opt_ecryptfs, "ecryptfs"}, |
4e561d38 RS |
76 | {Opt_error, NULL} |
77 | }; | |
78 | ||
7e70cb49 MZ |
79 | static const match_table_t key_tokens = { |
80 | {Opt_new, "new"}, | |
81 | {Opt_load, "load"}, | |
82 | {Opt_update, "update"}, | |
83 | {Opt_err, NULL} | |
84 | }; | |
85 | ||
86 | static int aes_get_sizes(void) | |
87 | { | |
88 | struct crypto_blkcipher *tfm; | |
89 | ||
90 | tfm = crypto_alloc_blkcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); | |
91 | if (IS_ERR(tfm)) { | |
92 | pr_err("encrypted_key: failed to alloc_cipher (%ld)\n", | |
93 | PTR_ERR(tfm)); | |
94 | return PTR_ERR(tfm); | |
95 | } | |
96 | ivsize = crypto_blkcipher_ivsize(tfm); | |
97 | blksize = crypto_blkcipher_blocksize(tfm); | |
98 | crypto_free_blkcipher(tfm); | |
99 | return 0; | |
100 | } | |
101 | ||
79a73d18 RS |
102 | /* |
103 | * valid_ecryptfs_desc - verify the description of a new/loaded encrypted key | |
104 | * | |
105 | * The description of a encrypted key with format 'ecryptfs' must contain | |
106 | * exactly 16 hexadecimal characters. | |
107 | * | |
108 | */ | |
109 | static int valid_ecryptfs_desc(const char *ecryptfs_desc) | |
110 | { | |
111 | int i; | |
112 | ||
113 | if (strlen(ecryptfs_desc) != KEY_ECRYPTFS_DESC_LEN) { | |
114 | pr_err("encrypted_key: key description must be %d hexadecimal " | |
115 | "characters long\n", KEY_ECRYPTFS_DESC_LEN); | |
116 | return -EINVAL; | |
117 | } | |
118 | ||
119 | for (i = 0; i < KEY_ECRYPTFS_DESC_LEN; i++) { | |
120 | if (!isxdigit(ecryptfs_desc[i])) { | |
121 | pr_err("encrypted_key: key description must contain " | |
122 | "only hexadecimal characters\n"); | |
123 | return -EINVAL; | |
124 | } | |
125 | } | |
126 | ||
127 | return 0; | |
128 | } | |
129 | ||
7e70cb49 MZ |
130 | /* |
131 | * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key | |
132 | * | |
08fa2aa5 | 133 | * key-type:= "trusted:" | "user:" |
7e70cb49 MZ |
134 | * desc:= master-key description |
135 | * | |
136 | * Verify that 'key-type' is valid and that 'desc' exists. On key update, | |
137 | * only the master key description is permitted to change, not the key-type. | |
138 | * The key-type remains constant. | |
139 | * | |
140 | * On success returns 0, otherwise -EINVAL. | |
141 | */ | |
142 | static int valid_master_desc(const char *new_desc, const char *orig_desc) | |
143 | { | |
144 | if (!memcmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) { | |
145 | if (strlen(new_desc) == KEY_TRUSTED_PREFIX_LEN) | |
146 | goto out; | |
147 | if (orig_desc) | |
148 | if (memcmp(new_desc, orig_desc, KEY_TRUSTED_PREFIX_LEN)) | |
149 | goto out; | |
150 | } else if (!memcmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) { | |
151 | if (strlen(new_desc) == KEY_USER_PREFIX_LEN) | |
152 | goto out; | |
153 | if (orig_desc) | |
154 | if (memcmp(new_desc, orig_desc, KEY_USER_PREFIX_LEN)) | |
155 | goto out; | |
156 | } else | |
157 | goto out; | |
158 | return 0; | |
159 | out: | |
160 | return -EINVAL; | |
161 | } | |
162 | ||
163 | /* | |
164 | * datablob_parse - parse the keyctl data | |
165 | * | |
166 | * datablob format: | |
4e561d38 RS |
167 | * new [<format>] <master-key name> <decrypted data length> |
168 | * load [<format>] <master-key name> <decrypted data length> | |
169 | * <encrypted iv + data> | |
7e70cb49 MZ |
170 | * update <new-master-key name> |
171 | * | |
172 | * Tokenizes a copy of the keyctl data, returning a pointer to each token, | |
173 | * which is null terminated. | |
174 | * | |
175 | * On success returns 0, otherwise -EINVAL. | |
176 | */ | |
4e561d38 RS |
177 | static int datablob_parse(char *datablob, const char **format, |
178 | char **master_desc, char **decrypted_datalen, | |
179 | char **hex_encoded_iv) | |
7e70cb49 MZ |
180 | { |
181 | substring_t args[MAX_OPT_ARGS]; | |
182 | int ret = -EINVAL; | |
183 | int key_cmd; | |
4e561d38 RS |
184 | int key_format; |
185 | char *p, *keyword; | |
7e70cb49 | 186 | |
7103dff0 RS |
187 | keyword = strsep(&datablob, " \t"); |
188 | if (!keyword) { | |
189 | pr_info("encrypted_key: insufficient parameters specified\n"); | |
7e70cb49 | 190 | return ret; |
7103dff0 RS |
191 | } |
192 | key_cmd = match_token(keyword, key_tokens, args); | |
7e70cb49 | 193 | |
79a73d18 | 194 | /* Get optional format: default | ecryptfs */ |
4e561d38 RS |
195 | p = strsep(&datablob, " \t"); |
196 | if (!p) { | |
197 | pr_err("encrypted_key: insufficient parameters specified\n"); | |
198 | return ret; | |
199 | } | |
200 | ||
201 | key_format = match_token(p, key_format_tokens, args); | |
202 | switch (key_format) { | |
79a73d18 | 203 | case Opt_ecryptfs: |
4e561d38 RS |
204 | case Opt_default: |
205 | *format = p; | |
206 | *master_desc = strsep(&datablob, " \t"); | |
207 | break; | |
208 | case Opt_error: | |
209 | *master_desc = p; | |
210 | break; | |
211 | } | |
212 | ||
7103dff0 RS |
213 | if (!*master_desc) { |
214 | pr_info("encrypted_key: master key parameter is missing\n"); | |
7e70cb49 | 215 | goto out; |
7103dff0 | 216 | } |
7e70cb49 | 217 | |
7103dff0 RS |
218 | if (valid_master_desc(*master_desc, NULL) < 0) { |
219 | pr_info("encrypted_key: master key parameter \'%s\' " | |
220 | "is invalid\n", *master_desc); | |
7e70cb49 | 221 | goto out; |
7103dff0 | 222 | } |
7e70cb49 MZ |
223 | |
224 | if (decrypted_datalen) { | |
225 | *decrypted_datalen = strsep(&datablob, " \t"); | |
7103dff0 RS |
226 | if (!*decrypted_datalen) { |
227 | pr_info("encrypted_key: keylen parameter is missing\n"); | |
7e70cb49 | 228 | goto out; |
7103dff0 | 229 | } |
7e70cb49 MZ |
230 | } |
231 | ||
232 | switch (key_cmd) { | |
233 | case Opt_new: | |
7103dff0 RS |
234 | if (!decrypted_datalen) { |
235 | pr_info("encrypted_key: keyword \'%s\' not allowed " | |
236 | "when called from .update method\n", keyword); | |
7e70cb49 | 237 | break; |
7103dff0 | 238 | } |
7e70cb49 MZ |
239 | ret = 0; |
240 | break; | |
241 | case Opt_load: | |
7103dff0 RS |
242 | if (!decrypted_datalen) { |
243 | pr_info("encrypted_key: keyword \'%s\' not allowed " | |
244 | "when called from .update method\n", keyword); | |
7e70cb49 | 245 | break; |
7103dff0 | 246 | } |
7e70cb49 | 247 | *hex_encoded_iv = strsep(&datablob, " \t"); |
7103dff0 RS |
248 | if (!*hex_encoded_iv) { |
249 | pr_info("encrypted_key: hex blob is missing\n"); | |
7e70cb49 | 250 | break; |
7103dff0 | 251 | } |
7e70cb49 MZ |
252 | ret = 0; |
253 | break; | |
254 | case Opt_update: | |
7103dff0 RS |
255 | if (decrypted_datalen) { |
256 | pr_info("encrypted_key: keyword \'%s\' not allowed " | |
257 | "when called from .instantiate method\n", | |
258 | keyword); | |
7e70cb49 | 259 | break; |
7103dff0 | 260 | } |
7e70cb49 MZ |
261 | ret = 0; |
262 | break; | |
263 | case Opt_err: | |
7103dff0 RS |
264 | pr_info("encrypted_key: keyword \'%s\' not recognized\n", |
265 | keyword); | |
7e70cb49 MZ |
266 | break; |
267 | } | |
268 | out: | |
269 | return ret; | |
270 | } | |
271 | ||
272 | /* | |
273 | * datablob_format - format as an ascii string, before copying to userspace | |
274 | */ | |
275 | static char *datablob_format(struct encrypted_key_payload *epayload, | |
276 | size_t asciiblob_len) | |
277 | { | |
278 | char *ascii_buf, *bufp; | |
279 | u8 *iv = epayload->iv; | |
280 | int len; | |
281 | int i; | |
282 | ||
283 | ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL); | |
284 | if (!ascii_buf) | |
285 | goto out; | |
286 | ||
287 | ascii_buf[asciiblob_len] = '\0'; | |
288 | ||
289 | /* copy datablob master_desc and datalen strings */ | |
4e561d38 RS |
290 | len = sprintf(ascii_buf, "%s %s %s ", epayload->format, |
291 | epayload->master_desc, epayload->datalen); | |
7e70cb49 MZ |
292 | |
293 | /* convert the hex encoded iv, encrypted-data and HMAC to ascii */ | |
294 | bufp = &ascii_buf[len]; | |
295 | for (i = 0; i < (asciiblob_len - len) / 2; i++) | |
296 | bufp = pack_hex_byte(bufp, iv[i]); | |
297 | out: | |
298 | return ascii_buf; | |
299 | } | |
300 | ||
301 | /* | |
302 | * request_trusted_key - request the trusted key | |
303 | * | |
304 | * Trusted keys are sealed to PCRs and other metadata. Although userspace | |
305 | * manages both trusted/encrypted key-types, like the encrypted key type | |
306 | * data, trusted key type data is not visible decrypted from userspace. | |
307 | */ | |
308 | static struct key *request_trusted_key(const char *trusted_desc, | |
3b1826ce | 309 | u8 **master_key, size_t *master_keylen) |
7e70cb49 MZ |
310 | { |
311 | struct trusted_key_payload *tpayload; | |
312 | struct key *tkey; | |
313 | ||
314 | tkey = request_key(&key_type_trusted, trusted_desc, NULL); | |
315 | if (IS_ERR(tkey)) | |
316 | goto error; | |
317 | ||
318 | down_read(&tkey->sem); | |
319 | tpayload = rcu_dereference(tkey->payload.data); | |
320 | *master_key = tpayload->key; | |
321 | *master_keylen = tpayload->key_len; | |
322 | error: | |
323 | return tkey; | |
324 | } | |
325 | ||
326 | /* | |
327 | * request_user_key - request the user key | |
328 | * | |
329 | * Use a user provided key to encrypt/decrypt an encrypted-key. | |
330 | */ | |
331 | static struct key *request_user_key(const char *master_desc, u8 **master_key, | |
3b1826ce | 332 | size_t *master_keylen) |
7e70cb49 MZ |
333 | { |
334 | struct user_key_payload *upayload; | |
335 | struct key *ukey; | |
336 | ||
337 | ukey = request_key(&key_type_user, master_desc, NULL); | |
338 | if (IS_ERR(ukey)) | |
339 | goto error; | |
340 | ||
341 | down_read(&ukey->sem); | |
342 | upayload = rcu_dereference(ukey->payload.data); | |
343 | *master_key = upayload->data; | |
344 | *master_keylen = upayload->datalen; | |
345 | error: | |
346 | return ukey; | |
347 | } | |
348 | ||
3b1826ce | 349 | static struct sdesc *alloc_sdesc(struct crypto_shash *alg) |
7e70cb49 MZ |
350 | { |
351 | struct sdesc *sdesc; | |
352 | int size; | |
353 | ||
354 | size = sizeof(struct shash_desc) + crypto_shash_descsize(alg); | |
355 | sdesc = kmalloc(size, GFP_KERNEL); | |
356 | if (!sdesc) | |
357 | return ERR_PTR(-ENOMEM); | |
358 | sdesc->shash.tfm = alg; | |
359 | sdesc->shash.flags = 0x0; | |
360 | return sdesc; | |
361 | } | |
362 | ||
3b1826ce MZ |
363 | static int calc_hmac(u8 *digest, const u8 *key, unsigned int keylen, |
364 | const u8 *buf, unsigned int buflen) | |
7e70cb49 MZ |
365 | { |
366 | struct sdesc *sdesc; | |
367 | int ret; | |
368 | ||
3b1826ce | 369 | sdesc = alloc_sdesc(hmacalg); |
7e70cb49 MZ |
370 | if (IS_ERR(sdesc)) { |
371 | pr_info("encrypted_key: can't alloc %s\n", hmac_alg); | |
372 | return PTR_ERR(sdesc); | |
373 | } | |
374 | ||
375 | ret = crypto_shash_setkey(hmacalg, key, keylen); | |
376 | if (!ret) | |
377 | ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest); | |
378 | kfree(sdesc); | |
379 | return ret; | |
380 | } | |
381 | ||
3b1826ce | 382 | static int calc_hash(u8 *digest, const u8 *buf, unsigned int buflen) |
7e70cb49 MZ |
383 | { |
384 | struct sdesc *sdesc; | |
385 | int ret; | |
386 | ||
3b1826ce | 387 | sdesc = alloc_sdesc(hashalg); |
7e70cb49 MZ |
388 | if (IS_ERR(sdesc)) { |
389 | pr_info("encrypted_key: can't alloc %s\n", hash_alg); | |
390 | return PTR_ERR(sdesc); | |
391 | } | |
392 | ||
393 | ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest); | |
394 | kfree(sdesc); | |
395 | return ret; | |
396 | } | |
397 | ||
398 | enum derived_key_type { ENC_KEY, AUTH_KEY }; | |
399 | ||
400 | /* Derive authentication/encryption key from trusted key */ | |
401 | static int get_derived_key(u8 *derived_key, enum derived_key_type key_type, | |
3b1826ce | 402 | const u8 *master_key, size_t master_keylen) |
7e70cb49 MZ |
403 | { |
404 | u8 *derived_buf; | |
405 | unsigned int derived_buf_len; | |
406 | int ret; | |
407 | ||
408 | derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen; | |
409 | if (derived_buf_len < HASH_SIZE) | |
410 | derived_buf_len = HASH_SIZE; | |
411 | ||
412 | derived_buf = kzalloc(derived_buf_len, GFP_KERNEL); | |
413 | if (!derived_buf) { | |
414 | pr_err("encrypted_key: out of memory\n"); | |
415 | return -ENOMEM; | |
416 | } | |
417 | if (key_type) | |
418 | strcpy(derived_buf, "AUTH_KEY"); | |
419 | else | |
420 | strcpy(derived_buf, "ENC_KEY"); | |
421 | ||
422 | memcpy(derived_buf + strlen(derived_buf) + 1, master_key, | |
423 | master_keylen); | |
424 | ret = calc_hash(derived_key, derived_buf, derived_buf_len); | |
425 | kfree(derived_buf); | |
426 | return ret; | |
427 | } | |
428 | ||
429 | static int init_blkcipher_desc(struct blkcipher_desc *desc, const u8 *key, | |
3b1826ce MZ |
430 | unsigned int key_len, const u8 *iv, |
431 | unsigned int ivsize) | |
7e70cb49 MZ |
432 | { |
433 | int ret; | |
434 | ||
435 | desc->tfm = crypto_alloc_blkcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); | |
436 | if (IS_ERR(desc->tfm)) { | |
437 | pr_err("encrypted_key: failed to load %s transform (%ld)\n", | |
438 | blkcipher_alg, PTR_ERR(desc->tfm)); | |
439 | return PTR_ERR(desc->tfm); | |
440 | } | |
441 | desc->flags = 0; | |
442 | ||
443 | ret = crypto_blkcipher_setkey(desc->tfm, key, key_len); | |
444 | if (ret < 0) { | |
445 | pr_err("encrypted_key: failed to setkey (%d)\n", ret); | |
446 | crypto_free_blkcipher(desc->tfm); | |
447 | return ret; | |
448 | } | |
449 | crypto_blkcipher_set_iv(desc->tfm, iv, ivsize); | |
450 | return 0; | |
451 | } | |
452 | ||
453 | static struct key *request_master_key(struct encrypted_key_payload *epayload, | |
3b1826ce | 454 | u8 **master_key, size_t *master_keylen) |
7e70cb49 MZ |
455 | { |
456 | struct key *mkey = NULL; | |
457 | ||
458 | if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX, | |
459 | KEY_TRUSTED_PREFIX_LEN)) { | |
460 | mkey = request_trusted_key(epayload->master_desc + | |
461 | KEY_TRUSTED_PREFIX_LEN, | |
462 | master_key, master_keylen); | |
463 | } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX, | |
464 | KEY_USER_PREFIX_LEN)) { | |
465 | mkey = request_user_key(epayload->master_desc + | |
466 | KEY_USER_PREFIX_LEN, | |
467 | master_key, master_keylen); | |
468 | } else | |
469 | goto out; | |
470 | ||
f91c2c5c | 471 | if (IS_ERR(mkey)) { |
7e70cb49 MZ |
472 | pr_info("encrypted_key: key %s not found", |
473 | epayload->master_desc); | |
f91c2c5c RS |
474 | goto out; |
475 | } | |
476 | ||
477 | dump_master_key(*master_key, *master_keylen); | |
7e70cb49 MZ |
478 | out: |
479 | return mkey; | |
480 | } | |
481 | ||
482 | /* Before returning data to userspace, encrypt decrypted data. */ | |
483 | static int derived_key_encrypt(struct encrypted_key_payload *epayload, | |
484 | const u8 *derived_key, | |
3b1826ce | 485 | unsigned int derived_keylen) |
7e70cb49 MZ |
486 | { |
487 | struct scatterlist sg_in[2]; | |
488 | struct scatterlist sg_out[1]; | |
489 | struct blkcipher_desc desc; | |
490 | unsigned int encrypted_datalen; | |
491 | unsigned int padlen; | |
492 | char pad[16]; | |
493 | int ret; | |
494 | ||
495 | encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); | |
496 | padlen = encrypted_datalen - epayload->decrypted_datalen; | |
497 | ||
498 | ret = init_blkcipher_desc(&desc, derived_key, derived_keylen, | |
499 | epayload->iv, ivsize); | |
500 | if (ret < 0) | |
501 | goto out; | |
502 | dump_decrypted_data(epayload); | |
503 | ||
504 | memset(pad, 0, sizeof pad); | |
505 | sg_init_table(sg_in, 2); | |
506 | sg_set_buf(&sg_in[0], epayload->decrypted_data, | |
507 | epayload->decrypted_datalen); | |
508 | sg_set_buf(&sg_in[1], pad, padlen); | |
509 | ||
510 | sg_init_table(sg_out, 1); | |
511 | sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen); | |
512 | ||
513 | ret = crypto_blkcipher_encrypt(&desc, sg_out, sg_in, encrypted_datalen); | |
514 | crypto_free_blkcipher(desc.tfm); | |
515 | if (ret < 0) | |
516 | pr_err("encrypted_key: failed to encrypt (%d)\n", ret); | |
517 | else | |
518 | dump_encrypted_data(epayload, encrypted_datalen); | |
519 | out: | |
520 | return ret; | |
521 | } | |
522 | ||
523 | static int datablob_hmac_append(struct encrypted_key_payload *epayload, | |
3b1826ce | 524 | const u8 *master_key, size_t master_keylen) |
7e70cb49 MZ |
525 | { |
526 | u8 derived_key[HASH_SIZE]; | |
527 | u8 *digest; | |
528 | int ret; | |
529 | ||
530 | ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); | |
531 | if (ret < 0) | |
532 | goto out; | |
533 | ||
4e561d38 | 534 | digest = epayload->format + epayload->datablob_len; |
7e70cb49 | 535 | ret = calc_hmac(digest, derived_key, sizeof derived_key, |
4e561d38 | 536 | epayload->format, epayload->datablob_len); |
7e70cb49 MZ |
537 | if (!ret) |
538 | dump_hmac(NULL, digest, HASH_SIZE); | |
539 | out: | |
540 | return ret; | |
541 | } | |
542 | ||
543 | /* verify HMAC before decrypting encrypted key */ | |
544 | static int datablob_hmac_verify(struct encrypted_key_payload *epayload, | |
4e561d38 RS |
545 | const u8 *format, const u8 *master_key, |
546 | size_t master_keylen) | |
7e70cb49 MZ |
547 | { |
548 | u8 derived_key[HASH_SIZE]; | |
549 | u8 digest[HASH_SIZE]; | |
550 | int ret; | |
4e561d38 RS |
551 | char *p; |
552 | unsigned short len; | |
7e70cb49 MZ |
553 | |
554 | ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); | |
555 | if (ret < 0) | |
556 | goto out; | |
557 | ||
4e561d38 RS |
558 | len = epayload->datablob_len; |
559 | if (!format) { | |
560 | p = epayload->master_desc; | |
561 | len -= strlen(epayload->format) + 1; | |
562 | } else | |
563 | p = epayload->format; | |
564 | ||
565 | ret = calc_hmac(digest, derived_key, sizeof derived_key, p, len); | |
7e70cb49 MZ |
566 | if (ret < 0) |
567 | goto out; | |
4e561d38 | 568 | ret = memcmp(digest, epayload->format + epayload->datablob_len, |
7e70cb49 MZ |
569 | sizeof digest); |
570 | if (ret) { | |
571 | ret = -EINVAL; | |
572 | dump_hmac("datablob", | |
4e561d38 | 573 | epayload->format + epayload->datablob_len, |
7e70cb49 MZ |
574 | HASH_SIZE); |
575 | dump_hmac("calc", digest, HASH_SIZE); | |
576 | } | |
577 | out: | |
578 | return ret; | |
579 | } | |
580 | ||
581 | static int derived_key_decrypt(struct encrypted_key_payload *epayload, | |
582 | const u8 *derived_key, | |
3b1826ce | 583 | unsigned int derived_keylen) |
7e70cb49 MZ |
584 | { |
585 | struct scatterlist sg_in[1]; | |
586 | struct scatterlist sg_out[2]; | |
587 | struct blkcipher_desc desc; | |
588 | unsigned int encrypted_datalen; | |
589 | char pad[16]; | |
590 | int ret; | |
591 | ||
592 | encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); | |
593 | ret = init_blkcipher_desc(&desc, derived_key, derived_keylen, | |
594 | epayload->iv, ivsize); | |
595 | if (ret < 0) | |
596 | goto out; | |
597 | dump_encrypted_data(epayload, encrypted_datalen); | |
598 | ||
599 | memset(pad, 0, sizeof pad); | |
600 | sg_init_table(sg_in, 1); | |
601 | sg_init_table(sg_out, 2); | |
602 | sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen); | |
603 | sg_set_buf(&sg_out[0], epayload->decrypted_data, | |
3b1826ce | 604 | epayload->decrypted_datalen); |
7e70cb49 MZ |
605 | sg_set_buf(&sg_out[1], pad, sizeof pad); |
606 | ||
607 | ret = crypto_blkcipher_decrypt(&desc, sg_out, sg_in, encrypted_datalen); | |
608 | crypto_free_blkcipher(desc.tfm); | |
609 | if (ret < 0) | |
610 | goto out; | |
611 | dump_decrypted_data(epayload); | |
612 | out: | |
613 | return ret; | |
614 | } | |
615 | ||
616 | /* Allocate memory for decrypted key and datablob. */ | |
617 | static struct encrypted_key_payload *encrypted_key_alloc(struct key *key, | |
4e561d38 | 618 | const char *format, |
7e70cb49 MZ |
619 | const char *master_desc, |
620 | const char *datalen) | |
621 | { | |
622 | struct encrypted_key_payload *epayload = NULL; | |
623 | unsigned short datablob_len; | |
624 | unsigned short decrypted_datalen; | |
4e561d38 | 625 | unsigned short payload_datalen; |
7e70cb49 | 626 | unsigned int encrypted_datalen; |
4e561d38 | 627 | unsigned int format_len; |
7e70cb49 MZ |
628 | long dlen; |
629 | int ret; | |
630 | ||
631 | ret = strict_strtol(datalen, 10, &dlen); | |
632 | if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE) | |
633 | return ERR_PTR(-EINVAL); | |
634 | ||
4e561d38 | 635 | format_len = (!format) ? strlen(key_format_default) : strlen(format); |
7e70cb49 | 636 | decrypted_datalen = dlen; |
4e561d38 | 637 | payload_datalen = decrypted_datalen; |
79a73d18 RS |
638 | if (format && !strcmp(format, key_format_ecryptfs)) { |
639 | if (dlen != ECRYPTFS_MAX_KEY_BYTES) { | |
640 | pr_err("encrypted_key: keylen for the ecryptfs format " | |
641 | "must be equal to %d bytes\n", | |
642 | ECRYPTFS_MAX_KEY_BYTES); | |
643 | return ERR_PTR(-EINVAL); | |
644 | } | |
645 | decrypted_datalen = ECRYPTFS_MAX_KEY_BYTES; | |
646 | payload_datalen = sizeof(struct ecryptfs_auth_tok); | |
647 | } | |
648 | ||
7e70cb49 MZ |
649 | encrypted_datalen = roundup(decrypted_datalen, blksize); |
650 | ||
4e561d38 RS |
651 | datablob_len = format_len + 1 + strlen(master_desc) + 1 |
652 | + strlen(datalen) + 1 + ivsize + 1 + encrypted_datalen; | |
7e70cb49 | 653 | |
4e561d38 | 654 | ret = key_payload_reserve(key, payload_datalen + datablob_len |
7e70cb49 MZ |
655 | + HASH_SIZE + 1); |
656 | if (ret < 0) | |
657 | return ERR_PTR(ret); | |
658 | ||
4e561d38 | 659 | epayload = kzalloc(sizeof(*epayload) + payload_datalen + |
7e70cb49 MZ |
660 | datablob_len + HASH_SIZE + 1, GFP_KERNEL); |
661 | if (!epayload) | |
662 | return ERR_PTR(-ENOMEM); | |
663 | ||
4e561d38 | 664 | epayload->payload_datalen = payload_datalen; |
7e70cb49 MZ |
665 | epayload->decrypted_datalen = decrypted_datalen; |
666 | epayload->datablob_len = datablob_len; | |
667 | return epayload; | |
668 | } | |
669 | ||
670 | static int encrypted_key_decrypt(struct encrypted_key_payload *epayload, | |
4e561d38 | 671 | const char *format, const char *hex_encoded_iv) |
7e70cb49 MZ |
672 | { |
673 | struct key *mkey; | |
674 | u8 derived_key[HASH_SIZE]; | |
675 | u8 *master_key; | |
676 | u8 *hmac; | |
1f35065a | 677 | const char *hex_encoded_data; |
7e70cb49 | 678 | unsigned int encrypted_datalen; |
3b1826ce | 679 | size_t master_keylen; |
1f35065a | 680 | size_t asciilen; |
7e70cb49 MZ |
681 | int ret; |
682 | ||
683 | encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); | |
1f35065a MZ |
684 | asciilen = (ivsize + 1 + encrypted_datalen + HASH_SIZE) * 2; |
685 | if (strlen(hex_encoded_iv) != asciilen) | |
686 | return -EINVAL; | |
687 | ||
688 | hex_encoded_data = hex_encoded_iv + (2 * ivsize) + 2; | |
7e70cb49 MZ |
689 | hex2bin(epayload->iv, hex_encoded_iv, ivsize); |
690 | hex2bin(epayload->encrypted_data, hex_encoded_data, encrypted_datalen); | |
691 | ||
4e561d38 | 692 | hmac = epayload->format + epayload->datablob_len; |
7e70cb49 MZ |
693 | hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2), HASH_SIZE); |
694 | ||
695 | mkey = request_master_key(epayload, &master_key, &master_keylen); | |
696 | if (IS_ERR(mkey)) | |
697 | return PTR_ERR(mkey); | |
698 | ||
4e561d38 | 699 | ret = datablob_hmac_verify(epayload, format, master_key, master_keylen); |
7e70cb49 MZ |
700 | if (ret < 0) { |
701 | pr_err("encrypted_key: bad hmac (%d)\n", ret); | |
702 | goto out; | |
703 | } | |
704 | ||
705 | ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); | |
706 | if (ret < 0) | |
707 | goto out; | |
708 | ||
709 | ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key); | |
710 | if (ret < 0) | |
711 | pr_err("encrypted_key: failed to decrypt key (%d)\n", ret); | |
712 | out: | |
713 | up_read(&mkey->sem); | |
714 | key_put(mkey); | |
715 | return ret; | |
716 | } | |
717 | ||
718 | static void __ekey_init(struct encrypted_key_payload *epayload, | |
4e561d38 RS |
719 | const char *format, const char *master_desc, |
720 | const char *datalen) | |
7e70cb49 | 721 | { |
4e561d38 RS |
722 | unsigned int format_len; |
723 | ||
724 | format_len = (!format) ? strlen(key_format_default) : strlen(format); | |
725 | epayload->format = epayload->payload_data + epayload->payload_datalen; | |
726 | epayload->master_desc = epayload->format + format_len + 1; | |
7e70cb49 MZ |
727 | epayload->datalen = epayload->master_desc + strlen(master_desc) + 1; |
728 | epayload->iv = epayload->datalen + strlen(datalen) + 1; | |
729 | epayload->encrypted_data = epayload->iv + ivsize + 1; | |
4e561d38 | 730 | epayload->decrypted_data = epayload->payload_data; |
7e70cb49 | 731 | |
4e561d38 RS |
732 | if (!format) |
733 | memcpy(epayload->format, key_format_default, format_len); | |
79a73d18 RS |
734 | else { |
735 | if (!strcmp(format, key_format_ecryptfs)) | |
736 | epayload->decrypted_data = | |
737 | ecryptfs_get_auth_tok_key((struct ecryptfs_auth_tok *)epayload->payload_data); | |
738 | ||
4e561d38 | 739 | memcpy(epayload->format, format, format_len); |
79a73d18 RS |
740 | } |
741 | ||
7e70cb49 MZ |
742 | memcpy(epayload->master_desc, master_desc, strlen(master_desc)); |
743 | memcpy(epayload->datalen, datalen, strlen(datalen)); | |
744 | } | |
745 | ||
746 | /* | |
747 | * encrypted_init - initialize an encrypted key | |
748 | * | |
749 | * For a new key, use a random number for both the iv and data | |
750 | * itself. For an old key, decrypt the hex encoded data. | |
751 | */ | |
752 | static int encrypted_init(struct encrypted_key_payload *epayload, | |
79a73d18 RS |
753 | const char *key_desc, const char *format, |
754 | const char *master_desc, const char *datalen, | |
755 | const char *hex_encoded_iv) | |
7e70cb49 MZ |
756 | { |
757 | int ret = 0; | |
758 | ||
79a73d18 RS |
759 | if (format && !strcmp(format, key_format_ecryptfs)) { |
760 | ret = valid_ecryptfs_desc(key_desc); | |
761 | if (ret < 0) | |
762 | return ret; | |
763 | ||
764 | ecryptfs_fill_auth_tok((struct ecryptfs_auth_tok *)epayload->payload_data, | |
765 | key_desc); | |
766 | } | |
767 | ||
4e561d38 | 768 | __ekey_init(epayload, format, master_desc, datalen); |
1f35065a | 769 | if (!hex_encoded_iv) { |
7e70cb49 MZ |
770 | get_random_bytes(epayload->iv, ivsize); |
771 | ||
772 | get_random_bytes(epayload->decrypted_data, | |
773 | epayload->decrypted_datalen); | |
774 | } else | |
4e561d38 | 775 | ret = encrypted_key_decrypt(epayload, format, hex_encoded_iv); |
7e70cb49 MZ |
776 | return ret; |
777 | } | |
778 | ||
779 | /* | |
780 | * encrypted_instantiate - instantiate an encrypted key | |
781 | * | |
782 | * Decrypt an existing encrypted datablob or create a new encrypted key | |
783 | * based on a kernel random number. | |
784 | * | |
785 | * On success, return 0. Otherwise return errno. | |
786 | */ | |
787 | static int encrypted_instantiate(struct key *key, const void *data, | |
788 | size_t datalen) | |
789 | { | |
790 | struct encrypted_key_payload *epayload = NULL; | |
791 | char *datablob = NULL; | |
4e561d38 | 792 | const char *format = NULL; |
7e70cb49 MZ |
793 | char *master_desc = NULL; |
794 | char *decrypted_datalen = NULL; | |
795 | char *hex_encoded_iv = NULL; | |
7e70cb49 MZ |
796 | int ret; |
797 | ||
798 | if (datalen <= 0 || datalen > 32767 || !data) | |
799 | return -EINVAL; | |
800 | ||
801 | datablob = kmalloc(datalen + 1, GFP_KERNEL); | |
802 | if (!datablob) | |
803 | return -ENOMEM; | |
804 | datablob[datalen] = 0; | |
805 | memcpy(datablob, data, datalen); | |
4e561d38 RS |
806 | ret = datablob_parse(datablob, &format, &master_desc, |
807 | &decrypted_datalen, &hex_encoded_iv); | |
7e70cb49 MZ |
808 | if (ret < 0) |
809 | goto out; | |
810 | ||
4e561d38 RS |
811 | epayload = encrypted_key_alloc(key, format, master_desc, |
812 | decrypted_datalen); | |
7e70cb49 MZ |
813 | if (IS_ERR(epayload)) { |
814 | ret = PTR_ERR(epayload); | |
815 | goto out; | |
816 | } | |
79a73d18 RS |
817 | ret = encrypted_init(epayload, key->description, format, master_desc, |
818 | decrypted_datalen, hex_encoded_iv); | |
7e70cb49 MZ |
819 | if (ret < 0) { |
820 | kfree(epayload); | |
821 | goto out; | |
822 | } | |
823 | ||
824 | rcu_assign_pointer(key->payload.data, epayload); | |
825 | out: | |
826 | kfree(datablob); | |
827 | return ret; | |
828 | } | |
829 | ||
830 | static void encrypted_rcu_free(struct rcu_head *rcu) | |
831 | { | |
832 | struct encrypted_key_payload *epayload; | |
833 | ||
834 | epayload = container_of(rcu, struct encrypted_key_payload, rcu); | |
835 | memset(epayload->decrypted_data, 0, epayload->decrypted_datalen); | |
836 | kfree(epayload); | |
837 | } | |
838 | ||
839 | /* | |
840 | * encrypted_update - update the master key description | |
841 | * | |
842 | * Change the master key description for an existing encrypted key. | |
843 | * The next read will return an encrypted datablob using the new | |
844 | * master key description. | |
845 | * | |
846 | * On success, return 0. Otherwise return errno. | |
847 | */ | |
848 | static int encrypted_update(struct key *key, const void *data, size_t datalen) | |
849 | { | |
850 | struct encrypted_key_payload *epayload = key->payload.data; | |
851 | struct encrypted_key_payload *new_epayload; | |
852 | char *buf; | |
853 | char *new_master_desc = NULL; | |
4e561d38 | 854 | const char *format = NULL; |
7e70cb49 MZ |
855 | int ret = 0; |
856 | ||
857 | if (datalen <= 0 || datalen > 32767 || !data) | |
858 | return -EINVAL; | |
859 | ||
860 | buf = kmalloc(datalen + 1, GFP_KERNEL); | |
861 | if (!buf) | |
862 | return -ENOMEM; | |
863 | ||
864 | buf[datalen] = 0; | |
865 | memcpy(buf, data, datalen); | |
4e561d38 | 866 | ret = datablob_parse(buf, &format, &new_master_desc, NULL, NULL); |
7e70cb49 MZ |
867 | if (ret < 0) |
868 | goto out; | |
869 | ||
870 | ret = valid_master_desc(new_master_desc, epayload->master_desc); | |
871 | if (ret < 0) | |
872 | goto out; | |
873 | ||
4e561d38 RS |
874 | new_epayload = encrypted_key_alloc(key, epayload->format, |
875 | new_master_desc, epayload->datalen); | |
7e70cb49 MZ |
876 | if (IS_ERR(new_epayload)) { |
877 | ret = PTR_ERR(new_epayload); | |
878 | goto out; | |
879 | } | |
880 | ||
4e561d38 RS |
881 | __ekey_init(new_epayload, epayload->format, new_master_desc, |
882 | epayload->datalen); | |
7e70cb49 MZ |
883 | |
884 | memcpy(new_epayload->iv, epayload->iv, ivsize); | |
4e561d38 RS |
885 | memcpy(new_epayload->payload_data, epayload->payload_data, |
886 | epayload->payload_datalen); | |
7e70cb49 MZ |
887 | |
888 | rcu_assign_pointer(key->payload.data, new_epayload); | |
889 | call_rcu(&epayload->rcu, encrypted_rcu_free); | |
890 | out: | |
891 | kfree(buf); | |
892 | return ret; | |
893 | } | |
894 | ||
895 | /* | |
896 | * encrypted_read - format and copy the encrypted data to userspace | |
897 | * | |
898 | * The resulting datablob format is: | |
899 | * <master-key name> <decrypted data length> <encrypted iv> <encrypted data> | |
900 | * | |
901 | * On success, return to userspace the encrypted key datablob size. | |
902 | */ | |
903 | static long encrypted_read(const struct key *key, char __user *buffer, | |
904 | size_t buflen) | |
905 | { | |
906 | struct encrypted_key_payload *epayload; | |
907 | struct key *mkey; | |
908 | u8 *master_key; | |
3b1826ce | 909 | size_t master_keylen; |
7e70cb49 MZ |
910 | char derived_key[HASH_SIZE]; |
911 | char *ascii_buf; | |
912 | size_t asciiblob_len; | |
913 | int ret; | |
914 | ||
633e804e | 915 | epayload = rcu_dereference_key(key); |
7e70cb49 MZ |
916 | |
917 | /* returns the hex encoded iv, encrypted-data, and hmac as ascii */ | |
918 | asciiblob_len = epayload->datablob_len + ivsize + 1 | |
919 | + roundup(epayload->decrypted_datalen, blksize) | |
920 | + (HASH_SIZE * 2); | |
921 | ||
922 | if (!buffer || buflen < asciiblob_len) | |
923 | return asciiblob_len; | |
924 | ||
925 | mkey = request_master_key(epayload, &master_key, &master_keylen); | |
926 | if (IS_ERR(mkey)) | |
927 | return PTR_ERR(mkey); | |
928 | ||
929 | ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); | |
930 | if (ret < 0) | |
931 | goto out; | |
932 | ||
933 | ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key); | |
934 | if (ret < 0) | |
935 | goto out; | |
936 | ||
937 | ret = datablob_hmac_append(epayload, master_key, master_keylen); | |
938 | if (ret < 0) | |
939 | goto out; | |
940 | ||
941 | ascii_buf = datablob_format(epayload, asciiblob_len); | |
942 | if (!ascii_buf) { | |
943 | ret = -ENOMEM; | |
944 | goto out; | |
945 | } | |
946 | ||
947 | up_read(&mkey->sem); | |
948 | key_put(mkey); | |
949 | ||
950 | if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0) | |
951 | ret = -EFAULT; | |
952 | kfree(ascii_buf); | |
953 | ||
954 | return asciiblob_len; | |
955 | out: | |
956 | up_read(&mkey->sem); | |
957 | key_put(mkey); | |
958 | return ret; | |
959 | } | |
960 | ||
961 | /* | |
962 | * encrypted_destroy - before freeing the key, clear the decrypted data | |
963 | * | |
964 | * Before freeing the key, clear the memory containing the decrypted | |
965 | * key data. | |
966 | */ | |
967 | static void encrypted_destroy(struct key *key) | |
968 | { | |
969 | struct encrypted_key_payload *epayload = key->payload.data; | |
970 | ||
971 | if (!epayload) | |
972 | return; | |
973 | ||
974 | memset(epayload->decrypted_data, 0, epayload->decrypted_datalen); | |
975 | kfree(key->payload.data); | |
976 | } | |
977 | ||
978 | struct key_type key_type_encrypted = { | |
979 | .name = "encrypted", | |
980 | .instantiate = encrypted_instantiate, | |
981 | .update = encrypted_update, | |
982 | .match = user_match, | |
983 | .destroy = encrypted_destroy, | |
984 | .describe = user_describe, | |
985 | .read = encrypted_read, | |
986 | }; | |
987 | EXPORT_SYMBOL_GPL(key_type_encrypted); | |
988 | ||
989 | static void encrypted_shash_release(void) | |
990 | { | |
991 | if (hashalg) | |
992 | crypto_free_shash(hashalg); | |
993 | if (hmacalg) | |
994 | crypto_free_shash(hmacalg); | |
995 | } | |
996 | ||
997 | static int __init encrypted_shash_alloc(void) | |
998 | { | |
999 | int ret; | |
1000 | ||
1001 | hmacalg = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC); | |
1002 | if (IS_ERR(hmacalg)) { | |
1003 | pr_info("encrypted_key: could not allocate crypto %s\n", | |
1004 | hmac_alg); | |
1005 | return PTR_ERR(hmacalg); | |
1006 | } | |
1007 | ||
1008 | hashalg = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC); | |
1009 | if (IS_ERR(hashalg)) { | |
1010 | pr_info("encrypted_key: could not allocate crypto %s\n", | |
1011 | hash_alg); | |
1012 | ret = PTR_ERR(hashalg); | |
1013 | goto hashalg_fail; | |
1014 | } | |
1015 | ||
1016 | return 0; | |
1017 | ||
1018 | hashalg_fail: | |
1019 | crypto_free_shash(hmacalg); | |
1020 | return ret; | |
1021 | } | |
1022 | ||
1023 | static int __init init_encrypted(void) | |
1024 | { | |
1025 | int ret; | |
1026 | ||
1027 | ret = encrypted_shash_alloc(); | |
1028 | if (ret < 0) | |
1029 | return ret; | |
1030 | ret = register_key_type(&key_type_encrypted); | |
1031 | if (ret < 0) | |
1032 | goto out; | |
1033 | return aes_get_sizes(); | |
1034 | out: | |
1035 | encrypted_shash_release(); | |
1036 | return ret; | |
b9703449 | 1037 | |
7e70cb49 MZ |
1038 | } |
1039 | ||
1040 | static void __exit cleanup_encrypted(void) | |
1041 | { | |
1042 | encrypted_shash_release(); | |
1043 | unregister_key_type(&key_type_encrypted); | |
1044 | } | |
1045 | ||
1046 | late_initcall(init_encrypted); | |
1047 | module_exit(cleanup_encrypted); | |
1048 | ||
1049 | MODULE_LICENSE("GPL"); |