Commit 7e70cb4978507cf31d76b90e4cfb4c28cad87f0c
Committed by
James Morris
1 parent
d00a1c72f7
Exists in
master
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20 other branches
keys: add new key-type encrypted
Define a new kernel key-type called 'encrypted'. Encrypted keys are kernel generated random numbers, which are encrypted/decrypted with a 'trusted' symmetric key. Encrypted keys are created/encrypted/decrypted in the kernel. Userspace only ever sees/stores encrypted blobs. Changelog: - bug fix: replaced master-key rcu based locking with semaphore (reported by David Howells) - Removed memset of crypto_shash_digest() digest output - Replaced verification of 'key-type:key-desc' using strcspn(), with one based on string constants. - Moved documentation to Documentation/keys-trusted-encrypted.txt - Replace hash with shash (based on comments by David Howells) - Make lengths/counts size_t where possible (based on comments by David Howells) Could not convert most lengths, as crypto expects 'unsigned int' (size_t: on 32 bit is defined as unsigned int, but on 64 bit is unsigned long) - Add 'const' where possible (based on comments by David Howells) - allocate derived_buf dynamically to support arbitrary length master key (fixed by Roberto Sassu) - wait until late_initcall for crypto libraries to be registered - cleanup security/Kconfig - Add missing 'update' keyword (reported/fixed by Roberto Sassu) - Free epayload on failure to create key (reported/fixed by Roberto Sassu) - Increase the data size limit (requested by Roberto Sassu) - Crypto return codes are always 0 on success and negative on failure, remove unnecessary tests. - Replaced kzalloc() with kmalloc() Signed-off-by: Mimi Zohar <zohar@us.ibm.com> Signed-off-by: David Safford <safford@watson.ibm.com> Reviewed-by: Roberto Sassu <roberto.sassu@polito.it> Signed-off-by: James Morris <jmorris@namei.org>
Showing 5 changed files with 1009 additions and 0 deletions Side-by-side Diff
include/keys/encrypted-type.h
1 | +/* | |
2 | + * Copyright (C) 2010 IBM Corporation | |
3 | + * Author: Mimi Zohar <zohar@us.ibm.com> | |
4 | + * | |
5 | + * This program is free software; you can redistribute it and/or modify | |
6 | + * it under the terms of the GNU General Public License as published by | |
7 | + * the Free Software Foundation, version 2 of the License. | |
8 | + */ | |
9 | + | |
10 | +#ifndef _KEYS_ENCRYPTED_TYPE_H | |
11 | +#define _KEYS_ENCRYPTED_TYPE_H | |
12 | + | |
13 | +#include <linux/key.h> | |
14 | +#include <linux/rcupdate.h> | |
15 | + | |
16 | +struct encrypted_key_payload { | |
17 | + struct rcu_head rcu; | |
18 | + char *master_desc; /* datablob: master key name */ | |
19 | + char *datalen; /* datablob: decrypted key length */ | |
20 | + u8 *iv; /* datablob: iv */ | |
21 | + u8 *encrypted_data; /* datablob: encrypted data */ | |
22 | + unsigned short datablob_len; /* length of datablob */ | |
23 | + unsigned short decrypted_datalen; /* decrypted data length */ | |
24 | + u8 decrypted_data[0]; /* decrypted data + datablob + hmac */ | |
25 | +}; | |
26 | + | |
27 | +extern struct key_type key_type_encrypted; | |
28 | + | |
29 | +#endif /* _KEYS_ENCRYPTED_TYPE_H */ |
security/Kconfig
... | ... | @@ -36,6 +36,22 @@ |
36 | 36 | |
37 | 37 | If you are unsure as to whether this is required, answer N. |
38 | 38 | |
39 | +config ENCRYPTED_KEYS | |
40 | + tristate "ENCRYPTED KEYS" | |
41 | + depends on KEYS && TRUSTED_KEYS | |
42 | + select CRYPTO_AES | |
43 | + select CRYPTO_CBC | |
44 | + select CRYPTO_SHA256 | |
45 | + select CRYPTO_RNG | |
46 | + help | |
47 | + This option provides support for create/encrypting/decrypting keys | |
48 | + in the kernel. Encrypted keys are kernel generated random numbers, | |
49 | + which are encrypted/decrypted with a 'master' symmetric key. The | |
50 | + 'master' key can be either a trusted-key or user-key type. | |
51 | + Userspace only ever sees/stores encrypted blobs. | |
52 | + | |
53 | + If you are unsure as to whether this is required, answer N. | |
54 | + | |
39 | 55 | config KEYS_DEBUG_PROC_KEYS |
40 | 56 | bool "Enable the /proc/keys file by which keys may be viewed" |
41 | 57 | depends on KEYS |
security/keys/Makefile
security/keys/encrypted_defined.c
1 | +/* | |
2 | + * Copyright (C) 2010 IBM Corporation | |
3 | + * | |
4 | + * Author: | |
5 | + * Mimi Zohar <zohar@us.ibm.com> | |
6 | + * | |
7 | + * This program is free software; you can redistribute it and/or modify | |
8 | + * it under the terms of the GNU General Public License as published by | |
9 | + * the Free Software Foundation, version 2 of the License. | |
10 | + * | |
11 | + * See Documentation/keys-trusted-encrypted.txt | |
12 | + */ | |
13 | + | |
14 | +#include <linux/uaccess.h> | |
15 | +#include <linux/module.h> | |
16 | +#include <linux/init.h> | |
17 | +#include <linux/slab.h> | |
18 | +#include <linux/parser.h> | |
19 | +#include <linux/string.h> | |
20 | +#include <keys/user-type.h> | |
21 | +#include <keys/trusted-type.h> | |
22 | +#include <keys/encrypted-type.h> | |
23 | +#include <linux/key-type.h> | |
24 | +#include <linux/random.h> | |
25 | +#include <linux/rcupdate.h> | |
26 | +#include <linux/scatterlist.h> | |
27 | +#include <linux/crypto.h> | |
28 | +#include <crypto/hash.h> | |
29 | +#include <crypto/sha.h> | |
30 | +#include <crypto/aes.h> | |
31 | + | |
32 | +#include "encrypted_defined.h" | |
33 | + | |
34 | +#define KEY_TRUSTED_PREFIX "trusted:" | |
35 | +#define KEY_TRUSTED_PREFIX_LEN (sizeof (KEY_TRUSTED_PREFIX) - 1) | |
36 | +#define KEY_USER_PREFIX "user:" | |
37 | +#define KEY_USER_PREFIX_LEN (sizeof (KEY_USER_PREFIX) - 1) | |
38 | + | |
39 | +#define HASH_SIZE SHA256_DIGEST_SIZE | |
40 | +#define MAX_DATA_SIZE 4096 | |
41 | +#define MIN_DATA_SIZE 20 | |
42 | + | |
43 | +static const char hash_alg[] = "sha256"; | |
44 | +static const char hmac_alg[] = "hmac(sha256)"; | |
45 | +static const char blkcipher_alg[] = "cbc(aes)"; | |
46 | +static unsigned int ivsize; | |
47 | +static int blksize; | |
48 | + | |
49 | +struct sdesc { | |
50 | + struct shash_desc shash; | |
51 | + char ctx[]; | |
52 | +}; | |
53 | + | |
54 | +static struct crypto_shash *hashalg; | |
55 | +static struct crypto_shash *hmacalg; | |
56 | + | |
57 | +enum { | |
58 | + Opt_err = -1, Opt_new, Opt_load, Opt_update | |
59 | +}; | |
60 | + | |
61 | +static const match_table_t key_tokens = { | |
62 | + {Opt_new, "new"}, | |
63 | + {Opt_load, "load"}, | |
64 | + {Opt_update, "update"}, | |
65 | + {Opt_err, NULL} | |
66 | +}; | |
67 | + | |
68 | +static int aes_get_sizes(void) | |
69 | +{ | |
70 | + struct crypto_blkcipher *tfm; | |
71 | + | |
72 | + tfm = crypto_alloc_blkcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); | |
73 | + if (IS_ERR(tfm)) { | |
74 | + pr_err("encrypted_key: failed to alloc_cipher (%ld)\n", | |
75 | + PTR_ERR(tfm)); | |
76 | + return PTR_ERR(tfm); | |
77 | + } | |
78 | + ivsize = crypto_blkcipher_ivsize(tfm); | |
79 | + blksize = crypto_blkcipher_blocksize(tfm); | |
80 | + crypto_free_blkcipher(tfm); | |
81 | + return 0; | |
82 | +} | |
83 | + | |
84 | +/* | |
85 | + * valid_master_desc - verify the 'key-type:desc' of a new/updated master-key | |
86 | + * | |
87 | + * key-type:= "trusted:" | "encrypted:" | |
88 | + * desc:= master-key description | |
89 | + * | |
90 | + * Verify that 'key-type' is valid and that 'desc' exists. On key update, | |
91 | + * only the master key description is permitted to change, not the key-type. | |
92 | + * The key-type remains constant. | |
93 | + * | |
94 | + * On success returns 0, otherwise -EINVAL. | |
95 | + */ | |
96 | +static int valid_master_desc(const char *new_desc, const char *orig_desc) | |
97 | +{ | |
98 | + if (!memcmp(new_desc, KEY_TRUSTED_PREFIX, KEY_TRUSTED_PREFIX_LEN)) { | |
99 | + if (strlen(new_desc) == KEY_TRUSTED_PREFIX_LEN) | |
100 | + goto out; | |
101 | + if (orig_desc) | |
102 | + if (memcmp(new_desc, orig_desc, KEY_TRUSTED_PREFIX_LEN)) | |
103 | + goto out; | |
104 | + } else if (!memcmp(new_desc, KEY_USER_PREFIX, KEY_USER_PREFIX_LEN)) { | |
105 | + if (strlen(new_desc) == KEY_USER_PREFIX_LEN) | |
106 | + goto out; | |
107 | + if (orig_desc) | |
108 | + if (memcmp(new_desc, orig_desc, KEY_USER_PREFIX_LEN)) | |
109 | + goto out; | |
110 | + } else | |
111 | + goto out; | |
112 | + return 0; | |
113 | +out: | |
114 | + return -EINVAL; | |
115 | +} | |
116 | + | |
117 | +/* | |
118 | + * datablob_parse - parse the keyctl data | |
119 | + * | |
120 | + * datablob format: | |
121 | + * new <master-key name> <decrypted data length> | |
122 | + * load <master-key name> <decrypted data length> <encrypted iv + data> | |
123 | + * update <new-master-key name> | |
124 | + * | |
125 | + * Tokenizes a copy of the keyctl data, returning a pointer to each token, | |
126 | + * which is null terminated. | |
127 | + * | |
128 | + * On success returns 0, otherwise -EINVAL. | |
129 | + */ | |
130 | +static int datablob_parse(char *datablob, char **master_desc, | |
131 | + char **decrypted_datalen, char **hex_encoded_iv, | |
132 | + char **hex_encoded_data) | |
133 | +{ | |
134 | + substring_t args[MAX_OPT_ARGS]; | |
135 | + int ret = -EINVAL; | |
136 | + int key_cmd; | |
137 | + char *p; | |
138 | + | |
139 | + p = strsep(&datablob, " \t"); | |
140 | + if (!p) | |
141 | + return ret; | |
142 | + key_cmd = match_token(p, key_tokens, args); | |
143 | + | |
144 | + *master_desc = strsep(&datablob, " \t"); | |
145 | + if (!*master_desc) | |
146 | + goto out; | |
147 | + | |
148 | + if (valid_master_desc(*master_desc, NULL) < 0) | |
149 | + goto out; | |
150 | + | |
151 | + if (decrypted_datalen) { | |
152 | + *decrypted_datalen = strsep(&datablob, " \t"); | |
153 | + if (!*decrypted_datalen) | |
154 | + goto out; | |
155 | + } | |
156 | + | |
157 | + switch (key_cmd) { | |
158 | + case Opt_new: | |
159 | + if (!decrypted_datalen) | |
160 | + break; | |
161 | + ret = 0; | |
162 | + break; | |
163 | + case Opt_load: | |
164 | + if (!decrypted_datalen) | |
165 | + break; | |
166 | + *hex_encoded_iv = strsep(&datablob, " \t"); | |
167 | + if (!*hex_encoded_iv) | |
168 | + break; | |
169 | + *hex_encoded_data = *hex_encoded_iv + (2 * ivsize) + 2; | |
170 | + ret = 0; | |
171 | + break; | |
172 | + case Opt_update: | |
173 | + if (decrypted_datalen) | |
174 | + break; | |
175 | + ret = 0; | |
176 | + break; | |
177 | + case Opt_err: | |
178 | + break; | |
179 | + } | |
180 | +out: | |
181 | + return ret; | |
182 | +} | |
183 | + | |
184 | +/* | |
185 | + * datablob_format - format as an ascii string, before copying to userspace | |
186 | + */ | |
187 | +static char *datablob_format(struct encrypted_key_payload *epayload, | |
188 | + size_t asciiblob_len) | |
189 | +{ | |
190 | + char *ascii_buf, *bufp; | |
191 | + u8 *iv = epayload->iv; | |
192 | + int len; | |
193 | + int i; | |
194 | + | |
195 | + ascii_buf = kmalloc(asciiblob_len + 1, GFP_KERNEL); | |
196 | + if (!ascii_buf) | |
197 | + goto out; | |
198 | + | |
199 | + ascii_buf[asciiblob_len] = '\0'; | |
200 | + | |
201 | + /* copy datablob master_desc and datalen strings */ | |
202 | + len = sprintf(ascii_buf, "%s %s ", epayload->master_desc, | |
203 | + epayload->datalen); | |
204 | + | |
205 | + /* convert the hex encoded iv, encrypted-data and HMAC to ascii */ | |
206 | + bufp = &ascii_buf[len]; | |
207 | + for (i = 0; i < (asciiblob_len - len) / 2; i++) | |
208 | + bufp = pack_hex_byte(bufp, iv[i]); | |
209 | +out: | |
210 | + return ascii_buf; | |
211 | +} | |
212 | + | |
213 | +/* | |
214 | + * request_trusted_key - request the trusted key | |
215 | + * | |
216 | + * Trusted keys are sealed to PCRs and other metadata. Although userspace | |
217 | + * manages both trusted/encrypted key-types, like the encrypted key type | |
218 | + * data, trusted key type data is not visible decrypted from userspace. | |
219 | + */ | |
220 | +static struct key *request_trusted_key(const char *trusted_desc, | |
221 | + u8 **master_key, | |
222 | + unsigned int *master_keylen) | |
223 | +{ | |
224 | + struct trusted_key_payload *tpayload; | |
225 | + struct key *tkey; | |
226 | + | |
227 | + tkey = request_key(&key_type_trusted, trusted_desc, NULL); | |
228 | + if (IS_ERR(tkey)) | |
229 | + goto error; | |
230 | + | |
231 | + down_read(&tkey->sem); | |
232 | + tpayload = rcu_dereference(tkey->payload.data); | |
233 | + *master_key = tpayload->key; | |
234 | + *master_keylen = tpayload->key_len; | |
235 | +error: | |
236 | + return tkey; | |
237 | +} | |
238 | + | |
239 | +/* | |
240 | + * request_user_key - request the user key | |
241 | + * | |
242 | + * Use a user provided key to encrypt/decrypt an encrypted-key. | |
243 | + */ | |
244 | +static struct key *request_user_key(const char *master_desc, u8 **master_key, | |
245 | + unsigned int *master_keylen) | |
246 | +{ | |
247 | + struct user_key_payload *upayload; | |
248 | + struct key *ukey; | |
249 | + | |
250 | + ukey = request_key(&key_type_user, master_desc, NULL); | |
251 | + if (IS_ERR(ukey)) | |
252 | + goto error; | |
253 | + | |
254 | + down_read(&ukey->sem); | |
255 | + upayload = rcu_dereference(ukey->payload.data); | |
256 | + *master_key = upayload->data; | |
257 | + *master_keylen = upayload->datalen; | |
258 | +error: | |
259 | + return ukey; | |
260 | +} | |
261 | + | |
262 | +static struct sdesc *init_sdesc(struct crypto_shash *alg) | |
263 | +{ | |
264 | + struct sdesc *sdesc; | |
265 | + int size; | |
266 | + | |
267 | + size = sizeof(struct shash_desc) + crypto_shash_descsize(alg); | |
268 | + sdesc = kmalloc(size, GFP_KERNEL); | |
269 | + if (!sdesc) | |
270 | + return ERR_PTR(-ENOMEM); | |
271 | + sdesc->shash.tfm = alg; | |
272 | + sdesc->shash.flags = 0x0; | |
273 | + return sdesc; | |
274 | +} | |
275 | + | |
276 | +static int calc_hmac(u8 *digest, const u8 *key, const unsigned int keylen, | |
277 | + const u8 *buf, const unsigned int buflen) | |
278 | +{ | |
279 | + struct sdesc *sdesc; | |
280 | + int ret; | |
281 | + | |
282 | + sdesc = init_sdesc(hmacalg); | |
283 | + if (IS_ERR(sdesc)) { | |
284 | + pr_info("encrypted_key: can't alloc %s\n", hmac_alg); | |
285 | + return PTR_ERR(sdesc); | |
286 | + } | |
287 | + | |
288 | + ret = crypto_shash_setkey(hmacalg, key, keylen); | |
289 | + if (!ret) | |
290 | + ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest); | |
291 | + kfree(sdesc); | |
292 | + return ret; | |
293 | +} | |
294 | + | |
295 | +static int calc_hash(u8 *digest, const u8 *buf, const unsigned int buflen) | |
296 | +{ | |
297 | + struct sdesc *sdesc; | |
298 | + int ret; | |
299 | + | |
300 | + sdesc = init_sdesc(hashalg); | |
301 | + if (IS_ERR(sdesc)) { | |
302 | + pr_info("encrypted_key: can't alloc %s\n", hash_alg); | |
303 | + return PTR_ERR(sdesc); | |
304 | + } | |
305 | + | |
306 | + ret = crypto_shash_digest(&sdesc->shash, buf, buflen, digest); | |
307 | + kfree(sdesc); | |
308 | + return ret; | |
309 | +} | |
310 | + | |
311 | +enum derived_key_type { ENC_KEY, AUTH_KEY }; | |
312 | + | |
313 | +/* Derive authentication/encryption key from trusted key */ | |
314 | +static int get_derived_key(u8 *derived_key, enum derived_key_type key_type, | |
315 | + const u8 *master_key, | |
316 | + const unsigned int master_keylen) | |
317 | +{ | |
318 | + u8 *derived_buf; | |
319 | + unsigned int derived_buf_len; | |
320 | + int ret; | |
321 | + | |
322 | + derived_buf_len = strlen("AUTH_KEY") + 1 + master_keylen; | |
323 | + if (derived_buf_len < HASH_SIZE) | |
324 | + derived_buf_len = HASH_SIZE; | |
325 | + | |
326 | + derived_buf = kzalloc(derived_buf_len, GFP_KERNEL); | |
327 | + if (!derived_buf) { | |
328 | + pr_err("encrypted_key: out of memory\n"); | |
329 | + return -ENOMEM; | |
330 | + } | |
331 | + if (key_type) | |
332 | + strcpy(derived_buf, "AUTH_KEY"); | |
333 | + else | |
334 | + strcpy(derived_buf, "ENC_KEY"); | |
335 | + | |
336 | + memcpy(derived_buf + strlen(derived_buf) + 1, master_key, | |
337 | + master_keylen); | |
338 | + ret = calc_hash(derived_key, derived_buf, derived_buf_len); | |
339 | + kfree(derived_buf); | |
340 | + return ret; | |
341 | +} | |
342 | + | |
343 | +static int init_blkcipher_desc(struct blkcipher_desc *desc, const u8 *key, | |
344 | + const unsigned int key_len, const u8 *iv, | |
345 | + const unsigned int ivsize) | |
346 | +{ | |
347 | + int ret; | |
348 | + | |
349 | + desc->tfm = crypto_alloc_blkcipher(blkcipher_alg, 0, CRYPTO_ALG_ASYNC); | |
350 | + if (IS_ERR(desc->tfm)) { | |
351 | + pr_err("encrypted_key: failed to load %s transform (%ld)\n", | |
352 | + blkcipher_alg, PTR_ERR(desc->tfm)); | |
353 | + return PTR_ERR(desc->tfm); | |
354 | + } | |
355 | + desc->flags = 0; | |
356 | + | |
357 | + ret = crypto_blkcipher_setkey(desc->tfm, key, key_len); | |
358 | + if (ret < 0) { | |
359 | + pr_err("encrypted_key: failed to setkey (%d)\n", ret); | |
360 | + crypto_free_blkcipher(desc->tfm); | |
361 | + return ret; | |
362 | + } | |
363 | + crypto_blkcipher_set_iv(desc->tfm, iv, ivsize); | |
364 | + return 0; | |
365 | +} | |
366 | + | |
367 | +static struct key *request_master_key(struct encrypted_key_payload *epayload, | |
368 | + u8 **master_key, | |
369 | + unsigned int *master_keylen) | |
370 | +{ | |
371 | + struct key *mkey = NULL; | |
372 | + | |
373 | + if (!strncmp(epayload->master_desc, KEY_TRUSTED_PREFIX, | |
374 | + KEY_TRUSTED_PREFIX_LEN)) { | |
375 | + mkey = request_trusted_key(epayload->master_desc + | |
376 | + KEY_TRUSTED_PREFIX_LEN, | |
377 | + master_key, master_keylen); | |
378 | + } else if (!strncmp(epayload->master_desc, KEY_USER_PREFIX, | |
379 | + KEY_USER_PREFIX_LEN)) { | |
380 | + mkey = request_user_key(epayload->master_desc + | |
381 | + KEY_USER_PREFIX_LEN, | |
382 | + master_key, master_keylen); | |
383 | + } else | |
384 | + goto out; | |
385 | + | |
386 | + if (IS_ERR(mkey)) | |
387 | + pr_info("encrypted_key: key %s not found", | |
388 | + epayload->master_desc); | |
389 | + if (mkey) | |
390 | + dump_master_key(*master_key, *master_keylen); | |
391 | +out: | |
392 | + return mkey; | |
393 | +} | |
394 | + | |
395 | +/* Before returning data to userspace, encrypt decrypted data. */ | |
396 | +static int derived_key_encrypt(struct encrypted_key_payload *epayload, | |
397 | + const u8 *derived_key, | |
398 | + const unsigned int derived_keylen) | |
399 | +{ | |
400 | + struct scatterlist sg_in[2]; | |
401 | + struct scatterlist sg_out[1]; | |
402 | + struct blkcipher_desc desc; | |
403 | + unsigned int encrypted_datalen; | |
404 | + unsigned int padlen; | |
405 | + char pad[16]; | |
406 | + int ret; | |
407 | + | |
408 | + encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); | |
409 | + padlen = encrypted_datalen - epayload->decrypted_datalen; | |
410 | + | |
411 | + ret = init_blkcipher_desc(&desc, derived_key, derived_keylen, | |
412 | + epayload->iv, ivsize); | |
413 | + if (ret < 0) | |
414 | + goto out; | |
415 | + dump_decrypted_data(epayload); | |
416 | + | |
417 | + memset(pad, 0, sizeof pad); | |
418 | + sg_init_table(sg_in, 2); | |
419 | + sg_set_buf(&sg_in[0], epayload->decrypted_data, | |
420 | + epayload->decrypted_datalen); | |
421 | + sg_set_buf(&sg_in[1], pad, padlen); | |
422 | + | |
423 | + sg_init_table(sg_out, 1); | |
424 | + sg_set_buf(sg_out, epayload->encrypted_data, encrypted_datalen); | |
425 | + | |
426 | + ret = crypto_blkcipher_encrypt(&desc, sg_out, sg_in, encrypted_datalen); | |
427 | + crypto_free_blkcipher(desc.tfm); | |
428 | + if (ret < 0) | |
429 | + pr_err("encrypted_key: failed to encrypt (%d)\n", ret); | |
430 | + else | |
431 | + dump_encrypted_data(epayload, encrypted_datalen); | |
432 | +out: | |
433 | + return ret; | |
434 | +} | |
435 | + | |
436 | +static int datablob_hmac_append(struct encrypted_key_payload *epayload, | |
437 | + const u8 *master_key, | |
438 | + const unsigned int master_keylen) | |
439 | +{ | |
440 | + u8 derived_key[HASH_SIZE]; | |
441 | + u8 *digest; | |
442 | + int ret; | |
443 | + | |
444 | + ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); | |
445 | + if (ret < 0) | |
446 | + goto out; | |
447 | + | |
448 | + digest = epayload->master_desc + epayload->datablob_len; | |
449 | + ret = calc_hmac(digest, derived_key, sizeof derived_key, | |
450 | + epayload->master_desc, epayload->datablob_len); | |
451 | + if (!ret) | |
452 | + dump_hmac(NULL, digest, HASH_SIZE); | |
453 | +out: | |
454 | + return ret; | |
455 | +} | |
456 | + | |
457 | +/* verify HMAC before decrypting encrypted key */ | |
458 | +static int datablob_hmac_verify(struct encrypted_key_payload *epayload, | |
459 | + const u8 *master_key, | |
460 | + const unsigned int master_keylen) | |
461 | +{ | |
462 | + u8 derived_key[HASH_SIZE]; | |
463 | + u8 digest[HASH_SIZE]; | |
464 | + int ret; | |
465 | + | |
466 | + ret = get_derived_key(derived_key, AUTH_KEY, master_key, master_keylen); | |
467 | + if (ret < 0) | |
468 | + goto out; | |
469 | + | |
470 | + ret = calc_hmac(digest, derived_key, sizeof derived_key, | |
471 | + epayload->master_desc, epayload->datablob_len); | |
472 | + if (ret < 0) | |
473 | + goto out; | |
474 | + ret = memcmp(digest, epayload->master_desc + epayload->datablob_len, | |
475 | + sizeof digest); | |
476 | + if (ret) { | |
477 | + ret = -EINVAL; | |
478 | + dump_hmac("datablob", | |
479 | + epayload->master_desc + epayload->datablob_len, | |
480 | + HASH_SIZE); | |
481 | + dump_hmac("calc", digest, HASH_SIZE); | |
482 | + } | |
483 | +out: | |
484 | + return ret; | |
485 | +} | |
486 | + | |
487 | +static int derived_key_decrypt(struct encrypted_key_payload *epayload, | |
488 | + const u8 *derived_key, | |
489 | + const unsigned int derived_keylen) | |
490 | +{ | |
491 | + struct scatterlist sg_in[1]; | |
492 | + struct scatterlist sg_out[2]; | |
493 | + struct blkcipher_desc desc; | |
494 | + unsigned int encrypted_datalen; | |
495 | + char pad[16]; | |
496 | + int ret; | |
497 | + | |
498 | + encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); | |
499 | + ret = init_blkcipher_desc(&desc, derived_key, derived_keylen, | |
500 | + epayload->iv, ivsize); | |
501 | + if (ret < 0) | |
502 | + goto out; | |
503 | + dump_encrypted_data(epayload, encrypted_datalen); | |
504 | + | |
505 | + memset(pad, 0, sizeof pad); | |
506 | + sg_init_table(sg_in, 1); | |
507 | + sg_init_table(sg_out, 2); | |
508 | + sg_set_buf(sg_in, epayload->encrypted_data, encrypted_datalen); | |
509 | + sg_set_buf(&sg_out[0], epayload->decrypted_data, | |
510 | + (unsigned int)epayload->decrypted_datalen); | |
511 | + sg_set_buf(&sg_out[1], pad, sizeof pad); | |
512 | + | |
513 | + ret = crypto_blkcipher_decrypt(&desc, sg_out, sg_in, encrypted_datalen); | |
514 | + crypto_free_blkcipher(desc.tfm); | |
515 | + if (ret < 0) | |
516 | + goto out; | |
517 | + dump_decrypted_data(epayload); | |
518 | +out: | |
519 | + return ret; | |
520 | +} | |
521 | + | |
522 | +/* Allocate memory for decrypted key and datablob. */ | |
523 | +static struct encrypted_key_payload *encrypted_key_alloc(struct key *key, | |
524 | + const char *master_desc, | |
525 | + const char *datalen) | |
526 | +{ | |
527 | + struct encrypted_key_payload *epayload = NULL; | |
528 | + unsigned short datablob_len; | |
529 | + unsigned short decrypted_datalen; | |
530 | + unsigned int encrypted_datalen; | |
531 | + long dlen; | |
532 | + int ret; | |
533 | + | |
534 | + ret = strict_strtol(datalen, 10, &dlen); | |
535 | + if (ret < 0 || dlen < MIN_DATA_SIZE || dlen > MAX_DATA_SIZE) | |
536 | + return ERR_PTR(-EINVAL); | |
537 | + | |
538 | + decrypted_datalen = dlen; | |
539 | + encrypted_datalen = roundup(decrypted_datalen, blksize); | |
540 | + | |
541 | + datablob_len = strlen(master_desc) + 1 + strlen(datalen) + 1 | |
542 | + + ivsize + 1 + encrypted_datalen; | |
543 | + | |
544 | + ret = key_payload_reserve(key, decrypted_datalen + datablob_len | |
545 | + + HASH_SIZE + 1); | |
546 | + if (ret < 0) | |
547 | + return ERR_PTR(ret); | |
548 | + | |
549 | + epayload = kzalloc(sizeof(*epayload) + decrypted_datalen + | |
550 | + datablob_len + HASH_SIZE + 1, GFP_KERNEL); | |
551 | + if (!epayload) | |
552 | + return ERR_PTR(-ENOMEM); | |
553 | + | |
554 | + epayload->decrypted_datalen = decrypted_datalen; | |
555 | + epayload->datablob_len = datablob_len; | |
556 | + return epayload; | |
557 | +} | |
558 | + | |
559 | +static int encrypted_key_decrypt(struct encrypted_key_payload *epayload, | |
560 | + const char *hex_encoded_iv, | |
561 | + const char *hex_encoded_data) | |
562 | +{ | |
563 | + struct key *mkey; | |
564 | + u8 derived_key[HASH_SIZE]; | |
565 | + u8 *master_key; | |
566 | + u8 *hmac; | |
567 | + unsigned int master_keylen; | |
568 | + unsigned int encrypted_datalen; | |
569 | + int ret; | |
570 | + | |
571 | + encrypted_datalen = roundup(epayload->decrypted_datalen, blksize); | |
572 | + hex2bin(epayload->iv, hex_encoded_iv, ivsize); | |
573 | + hex2bin(epayload->encrypted_data, hex_encoded_data, encrypted_datalen); | |
574 | + | |
575 | + hmac = epayload->master_desc + epayload->datablob_len; | |
576 | + hex2bin(hmac, hex_encoded_data + (encrypted_datalen * 2), HASH_SIZE); | |
577 | + | |
578 | + mkey = request_master_key(epayload, &master_key, &master_keylen); | |
579 | + if (IS_ERR(mkey)) | |
580 | + return PTR_ERR(mkey); | |
581 | + | |
582 | + ret = datablob_hmac_verify(epayload, master_key, master_keylen); | |
583 | + if (ret < 0) { | |
584 | + pr_err("encrypted_key: bad hmac (%d)\n", ret); | |
585 | + goto out; | |
586 | + } | |
587 | + | |
588 | + ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); | |
589 | + if (ret < 0) | |
590 | + goto out; | |
591 | + | |
592 | + ret = derived_key_decrypt(epayload, derived_key, sizeof derived_key); | |
593 | + if (ret < 0) | |
594 | + pr_err("encrypted_key: failed to decrypt key (%d)\n", ret); | |
595 | +out: | |
596 | + up_read(&mkey->sem); | |
597 | + key_put(mkey); | |
598 | + return ret; | |
599 | +} | |
600 | + | |
601 | +static void __ekey_init(struct encrypted_key_payload *epayload, | |
602 | + const char *master_desc, const char *datalen) | |
603 | +{ | |
604 | + epayload->master_desc = epayload->decrypted_data | |
605 | + + epayload->decrypted_datalen; | |
606 | + epayload->datalen = epayload->master_desc + strlen(master_desc) + 1; | |
607 | + epayload->iv = epayload->datalen + strlen(datalen) + 1; | |
608 | + epayload->encrypted_data = epayload->iv + ivsize + 1; | |
609 | + | |
610 | + memcpy(epayload->master_desc, master_desc, strlen(master_desc)); | |
611 | + memcpy(epayload->datalen, datalen, strlen(datalen)); | |
612 | +} | |
613 | + | |
614 | +/* | |
615 | + * encrypted_init - initialize an encrypted key | |
616 | + * | |
617 | + * For a new key, use a random number for both the iv and data | |
618 | + * itself. For an old key, decrypt the hex encoded data. | |
619 | + */ | |
620 | +static int encrypted_init(struct encrypted_key_payload *epayload, | |
621 | + const char *master_desc, const char *datalen, | |
622 | + const char *hex_encoded_iv, | |
623 | + const char *hex_encoded_data) | |
624 | +{ | |
625 | + int ret = 0; | |
626 | + | |
627 | + __ekey_init(epayload, master_desc, datalen); | |
628 | + if (!hex_encoded_data) { | |
629 | + get_random_bytes(epayload->iv, ivsize); | |
630 | + | |
631 | + get_random_bytes(epayload->decrypted_data, | |
632 | + epayload->decrypted_datalen); | |
633 | + } else | |
634 | + ret = encrypted_key_decrypt(epayload, hex_encoded_iv, | |
635 | + hex_encoded_data); | |
636 | + return ret; | |
637 | +} | |
638 | + | |
639 | +/* | |
640 | + * encrypted_instantiate - instantiate an encrypted key | |
641 | + * | |
642 | + * Decrypt an existing encrypted datablob or create a new encrypted key | |
643 | + * based on a kernel random number. | |
644 | + * | |
645 | + * On success, return 0. Otherwise return errno. | |
646 | + */ | |
647 | +static int encrypted_instantiate(struct key *key, const void *data, | |
648 | + size_t datalen) | |
649 | +{ | |
650 | + struct encrypted_key_payload *epayload = NULL; | |
651 | + char *datablob = NULL; | |
652 | + char *master_desc = NULL; | |
653 | + char *decrypted_datalen = NULL; | |
654 | + char *hex_encoded_iv = NULL; | |
655 | + char *hex_encoded_data = NULL; | |
656 | + int ret; | |
657 | + | |
658 | + if (datalen <= 0 || datalen > 32767 || !data) | |
659 | + return -EINVAL; | |
660 | + | |
661 | + datablob = kmalloc(datalen + 1, GFP_KERNEL); | |
662 | + if (!datablob) | |
663 | + return -ENOMEM; | |
664 | + datablob[datalen] = 0; | |
665 | + memcpy(datablob, data, datalen); | |
666 | + ret = datablob_parse(datablob, &master_desc, &decrypted_datalen, | |
667 | + &hex_encoded_iv, &hex_encoded_data); | |
668 | + if (ret < 0) | |
669 | + goto out; | |
670 | + | |
671 | + epayload = encrypted_key_alloc(key, master_desc, decrypted_datalen); | |
672 | + if (IS_ERR(epayload)) { | |
673 | + ret = PTR_ERR(epayload); | |
674 | + goto out; | |
675 | + } | |
676 | + ret = encrypted_init(epayload, master_desc, decrypted_datalen, | |
677 | + hex_encoded_iv, hex_encoded_data); | |
678 | + if (ret < 0) { | |
679 | + kfree(epayload); | |
680 | + goto out; | |
681 | + } | |
682 | + | |
683 | + rcu_assign_pointer(key->payload.data, epayload); | |
684 | +out: | |
685 | + kfree(datablob); | |
686 | + return ret; | |
687 | +} | |
688 | + | |
689 | +static void encrypted_rcu_free(struct rcu_head *rcu) | |
690 | +{ | |
691 | + struct encrypted_key_payload *epayload; | |
692 | + | |
693 | + epayload = container_of(rcu, struct encrypted_key_payload, rcu); | |
694 | + memset(epayload->decrypted_data, 0, epayload->decrypted_datalen); | |
695 | + kfree(epayload); | |
696 | +} | |
697 | + | |
698 | +/* | |
699 | + * encrypted_update - update the master key description | |
700 | + * | |
701 | + * Change the master key description for an existing encrypted key. | |
702 | + * The next read will return an encrypted datablob using the new | |
703 | + * master key description. | |
704 | + * | |
705 | + * On success, return 0. Otherwise return errno. | |
706 | + */ | |
707 | +static int encrypted_update(struct key *key, const void *data, size_t datalen) | |
708 | +{ | |
709 | + struct encrypted_key_payload *epayload = key->payload.data; | |
710 | + struct encrypted_key_payload *new_epayload; | |
711 | + char *buf; | |
712 | + char *new_master_desc = NULL; | |
713 | + int ret = 0; | |
714 | + | |
715 | + if (datalen <= 0 || datalen > 32767 || !data) | |
716 | + return -EINVAL; | |
717 | + | |
718 | + buf = kmalloc(datalen + 1, GFP_KERNEL); | |
719 | + if (!buf) | |
720 | + return -ENOMEM; | |
721 | + | |
722 | + buf[datalen] = 0; | |
723 | + memcpy(buf, data, datalen); | |
724 | + ret = datablob_parse(buf, &new_master_desc, NULL, NULL, NULL); | |
725 | + if (ret < 0) | |
726 | + goto out; | |
727 | + | |
728 | + ret = valid_master_desc(new_master_desc, epayload->master_desc); | |
729 | + if (ret < 0) | |
730 | + goto out; | |
731 | + | |
732 | + new_epayload = encrypted_key_alloc(key, new_master_desc, | |
733 | + epayload->datalen); | |
734 | + if (IS_ERR(new_epayload)) { | |
735 | + ret = PTR_ERR(new_epayload); | |
736 | + goto out; | |
737 | + } | |
738 | + | |
739 | + __ekey_init(new_epayload, new_master_desc, epayload->datalen); | |
740 | + | |
741 | + memcpy(new_epayload->iv, epayload->iv, ivsize); | |
742 | + memcpy(new_epayload->decrypted_data, epayload->decrypted_data, | |
743 | + epayload->decrypted_datalen); | |
744 | + | |
745 | + rcu_assign_pointer(key->payload.data, new_epayload); | |
746 | + call_rcu(&epayload->rcu, encrypted_rcu_free); | |
747 | +out: | |
748 | + kfree(buf); | |
749 | + return ret; | |
750 | +} | |
751 | + | |
752 | +/* | |
753 | + * encrypted_read - format and copy the encrypted data to userspace | |
754 | + * | |
755 | + * The resulting datablob format is: | |
756 | + * <master-key name> <decrypted data length> <encrypted iv> <encrypted data> | |
757 | + * | |
758 | + * On success, return to userspace the encrypted key datablob size. | |
759 | + */ | |
760 | +static long encrypted_read(const struct key *key, char __user *buffer, | |
761 | + size_t buflen) | |
762 | +{ | |
763 | + struct encrypted_key_payload *epayload; | |
764 | + struct key *mkey; | |
765 | + u8 *master_key; | |
766 | + unsigned int master_keylen; | |
767 | + char derived_key[HASH_SIZE]; | |
768 | + char *ascii_buf; | |
769 | + size_t asciiblob_len; | |
770 | + int ret; | |
771 | + | |
772 | + epayload = rcu_dereference_protected(key->payload.data, | |
773 | + rwsem_is_locked(&((struct key *)key)->sem)); | |
774 | + | |
775 | + /* returns the hex encoded iv, encrypted-data, and hmac as ascii */ | |
776 | + asciiblob_len = epayload->datablob_len + ivsize + 1 | |
777 | + + roundup(epayload->decrypted_datalen, blksize) | |
778 | + + (HASH_SIZE * 2); | |
779 | + | |
780 | + if (!buffer || buflen < asciiblob_len) | |
781 | + return asciiblob_len; | |
782 | + | |
783 | + mkey = request_master_key(epayload, &master_key, &master_keylen); | |
784 | + if (IS_ERR(mkey)) | |
785 | + return PTR_ERR(mkey); | |
786 | + | |
787 | + ret = get_derived_key(derived_key, ENC_KEY, master_key, master_keylen); | |
788 | + if (ret < 0) | |
789 | + goto out; | |
790 | + | |
791 | + ret = derived_key_encrypt(epayload, derived_key, sizeof derived_key); | |
792 | + if (ret < 0) | |
793 | + goto out; | |
794 | + | |
795 | + ret = datablob_hmac_append(epayload, master_key, master_keylen); | |
796 | + if (ret < 0) | |
797 | + goto out; | |
798 | + | |
799 | + ascii_buf = datablob_format(epayload, asciiblob_len); | |
800 | + if (!ascii_buf) { | |
801 | + ret = -ENOMEM; | |
802 | + goto out; | |
803 | + } | |
804 | + | |
805 | + up_read(&mkey->sem); | |
806 | + key_put(mkey); | |
807 | + | |
808 | + if (copy_to_user(buffer, ascii_buf, asciiblob_len) != 0) | |
809 | + ret = -EFAULT; | |
810 | + kfree(ascii_buf); | |
811 | + | |
812 | + return asciiblob_len; | |
813 | +out: | |
814 | + up_read(&mkey->sem); | |
815 | + key_put(mkey); | |
816 | + return ret; | |
817 | +} | |
818 | + | |
819 | +/* | |
820 | + * encrypted_destroy - before freeing the key, clear the decrypted data | |
821 | + * | |
822 | + * Before freeing the key, clear the memory containing the decrypted | |
823 | + * key data. | |
824 | + */ | |
825 | +static void encrypted_destroy(struct key *key) | |
826 | +{ | |
827 | + struct encrypted_key_payload *epayload = key->payload.data; | |
828 | + | |
829 | + if (!epayload) | |
830 | + return; | |
831 | + | |
832 | + memset(epayload->decrypted_data, 0, epayload->decrypted_datalen); | |
833 | + kfree(key->payload.data); | |
834 | +} | |
835 | + | |
836 | +struct key_type key_type_encrypted = { | |
837 | + .name = "encrypted", | |
838 | + .instantiate = encrypted_instantiate, | |
839 | + .update = encrypted_update, | |
840 | + .match = user_match, | |
841 | + .destroy = encrypted_destroy, | |
842 | + .describe = user_describe, | |
843 | + .read = encrypted_read, | |
844 | +}; | |
845 | +EXPORT_SYMBOL_GPL(key_type_encrypted); | |
846 | + | |
847 | +static void encrypted_shash_release(void) | |
848 | +{ | |
849 | + if (hashalg) | |
850 | + crypto_free_shash(hashalg); | |
851 | + if (hmacalg) | |
852 | + crypto_free_shash(hmacalg); | |
853 | +} | |
854 | + | |
855 | +static int __init encrypted_shash_alloc(void) | |
856 | +{ | |
857 | + int ret; | |
858 | + | |
859 | + hmacalg = crypto_alloc_shash(hmac_alg, 0, CRYPTO_ALG_ASYNC); | |
860 | + if (IS_ERR(hmacalg)) { | |
861 | + pr_info("encrypted_key: could not allocate crypto %s\n", | |
862 | + hmac_alg); | |
863 | + return PTR_ERR(hmacalg); | |
864 | + } | |
865 | + | |
866 | + hashalg = crypto_alloc_shash(hash_alg, 0, CRYPTO_ALG_ASYNC); | |
867 | + if (IS_ERR(hashalg)) { | |
868 | + pr_info("encrypted_key: could not allocate crypto %s\n", | |
869 | + hash_alg); | |
870 | + ret = PTR_ERR(hashalg); | |
871 | + goto hashalg_fail; | |
872 | + } | |
873 | + | |
874 | + return 0; | |
875 | + | |
876 | +hashalg_fail: | |
877 | + crypto_free_shash(hmacalg); | |
878 | + return ret; | |
879 | +} | |
880 | + | |
881 | +static int __init init_encrypted(void) | |
882 | +{ | |
883 | + int ret; | |
884 | + | |
885 | + ret = encrypted_shash_alloc(); | |
886 | + if (ret < 0) | |
887 | + return ret; | |
888 | + ret = register_key_type(&key_type_encrypted); | |
889 | + if (ret < 0) | |
890 | + goto out; | |
891 | + return aes_get_sizes(); | |
892 | +out: | |
893 | + encrypted_shash_release(); | |
894 | + return ret; | |
895 | + | |
896 | +} | |
897 | + | |
898 | +static void __exit cleanup_encrypted(void) | |
899 | +{ | |
900 | + encrypted_shash_release(); | |
901 | + unregister_key_type(&key_type_encrypted); | |
902 | +} | |
903 | + | |
904 | +late_initcall(init_encrypted); | |
905 | +module_exit(cleanup_encrypted); | |
906 | + | |
907 | +MODULE_LICENSE("GPL"); |
security/keys/encrypted_defined.h
1 | +#ifndef __ENCRYPTED_KEY_H | |
2 | +#define __ENCRYPTED_KEY_H | |
3 | + | |
4 | +#define ENCRYPTED_DEBUG 0 | |
5 | + | |
6 | +#if ENCRYPTED_DEBUG | |
7 | +static inline void dump_master_key(const u8 *master_key, | |
8 | + unsigned int master_keylen) | |
9 | +{ | |
10 | + print_hex_dump(KERN_ERR, "master key: ", DUMP_PREFIX_NONE, 32, 1, | |
11 | + master_key, master_keylen, 0); | |
12 | +} | |
13 | + | |
14 | +static inline void dump_decrypted_data(struct encrypted_key_payload *epayload) | |
15 | +{ | |
16 | + print_hex_dump(KERN_ERR, "decrypted data: ", DUMP_PREFIX_NONE, 32, 1, | |
17 | + epayload->decrypted_data, | |
18 | + epayload->decrypted_datalen, 0); | |
19 | +} | |
20 | + | |
21 | +static inline void dump_encrypted_data(struct encrypted_key_payload *epayload, | |
22 | + unsigned int encrypted_datalen) | |
23 | +{ | |
24 | + print_hex_dump(KERN_ERR, "encrypted data: ", DUMP_PREFIX_NONE, 32, 1, | |
25 | + epayload->encrypted_data, encrypted_datalen, 0); | |
26 | +} | |
27 | + | |
28 | +static inline void dump_hmac(const char *str, const u8 *digest, | |
29 | + unsigned int hmac_size) | |
30 | +{ | |
31 | + if (str) | |
32 | + pr_info("encrypted_key: %s", str); | |
33 | + print_hex_dump(KERN_ERR, "hmac: ", DUMP_PREFIX_NONE, 32, 1, digest, | |
34 | + hmac_size, 0); | |
35 | +} | |
36 | +#else | |
37 | +static inline void dump_master_key(const u8 *master_key, | |
38 | + unsigned int master_keylen) | |
39 | +{ | |
40 | +} | |
41 | + | |
42 | +static inline void dump_decrypted_data(struct encrypted_key_payload *epayload) | |
43 | +{ | |
44 | +} | |
45 | + | |
46 | +static inline void dump_encrypted_data(struct encrypted_key_payload *epayload, | |
47 | + unsigned int encrypted_datalen) | |
48 | +{ | |
49 | +} | |
50 | + | |
51 | +static inline void dump_hmac(const char *str, const u8 *digest, | |
52 | + unsigned int hmac_size) | |
53 | +{ | |
54 | +} | |
55 | +#endif | |
56 | +#endif |