1 /*
2 * DRBG: Deterministic Random Bits Generator
3 * Based on NIST Recommended DRBG from NIST SP800-90A with the following
4 * properties:
5 * * CTR DRBG with DF with AES-128, AES-192, AES-256 cores
6 * * Hash DRBG with DF with SHA-1, SHA-256, SHA-384, SHA-512 cores
7 * * HMAC DRBG with DF with SHA-1, SHA-256, SHA-384, SHA-512 cores
8 * * with and without prediction resistance
9 *
10 * Copyright Stephan Mueller <smueller@chronox.de>, 2014
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, and the entire permission notice in its entirety,
17 * including the disclaimer of warranties.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 3. The name of the author may not be used to endorse or promote
22 * products derived from this software without specific prior
23 * written permission.
24 *
25 * ALTERNATIVELY, this product may be distributed under the terms of
26 * the GNU General Public License, in which case the provisions of the GPL are
27 * required INSTEAD OF the above restrictions. (This clause is
28 * necessary due to a potential bad interaction between the GPL and
29 * the restrictions contained in a BSD-style copyright.)
30 *
31 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
32 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
33 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
34 * WHICH ARE HEREBY DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE
35 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
36 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
37 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
38 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
39 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
40 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
41 * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
42 * DAMAGE.
43 *
44 * DRBG Usage
45 * ==========
46 * The SP 800-90A DRBG allows the user to specify a personalization string
47 * for initialization as well as an additional information string for each
48 * random number request. The following code fragments show how a caller
49 * uses the kernel crypto API to use the full functionality of the DRBG.
50 *
51 * Usage without any additional data
52 * ---------------------------------
53 * struct crypto_rng *drng;
54 * int err;
55 * char data[DATALEN];
56 *
57 * drng = crypto_alloc_rng(drng_name, 0, 0);
58 * err = crypto_rng_get_bytes(drng, &data, DATALEN);
59 * crypto_free_rng(drng);
60 *
61 *
62 * Usage with personalization string during initialization
63 * -------------------------------------------------------
64 * struct crypto_rng *drng;
65 * int err;
66 * char data[DATALEN];
67 * struct drbg_string pers;
68 * char personalization[11] = "some-string";
69 *
70 * drbg_string_fill(&pers, personalization, strlen(personalization));
71 * drng = crypto_alloc_rng(drng_name, 0, 0);
72 * // The reset completely re-initializes the DRBG with the provided
73 * // personalization string
74 * err = crypto_rng_reset(drng, &personalization, strlen(personalization));
75 * err = crypto_rng_get_bytes(drng, &data, DATALEN);
76 * crypto_free_rng(drng);
77 *
78 *
79 * Usage with additional information string during random number request
80 * ---------------------------------------------------------------------
81 * struct crypto_rng *drng;
82 * int err;
83 * char data[DATALEN];
84 * char addtl_string[11] = "some-string";
85 * string drbg_string addtl;
86 *
87 * drbg_string_fill(&addtl, addtl_string, strlen(addtl_string));
88 * drng = crypto_alloc_rng(drng_name, 0, 0);
89 * // The following call is a wrapper to crypto_rng_get_bytes() and returns
90 * // the same error codes.
91 * err = crypto_drbg_get_bytes_addtl(drng, &data, DATALEN, &addtl);
92 * crypto_free_rng(drng);
93 *
94 *
95 * Usage with personalization and additional information strings
96 * -------------------------------------------------------------
97 * Just mix both scenarios above.
98 */
99
100 #include <crypto/drbg.h>
101 #include <linux/kernel.h>
102
103 /***************************************************************
104 * Backend cipher definitions available to DRBG
105 ***************************************************************/
106
107 /*
108 * The order of the DRBG definitions here matter: every DRBG is registered
109 * as stdrng. Each DRBG receives an increasing cra_priority values the later
110 * they are defined in this array (see drbg_fill_array).
111 *
112 * HMAC DRBGs are favored over Hash DRBGs over CTR DRBGs, and
113 * the SHA256 / AES 256 over other ciphers. Thus, the favored
114 * DRBGs are the latest entries in this array.
115 */
116 static const struct drbg_core drbg_cores[] = {
117 #ifdef CONFIG_CRYPTO_DRBG_CTR
118 {
119 .flags = DRBG_CTR | DRBG_STRENGTH128,
120 .statelen = 32, /* 256 bits as defined in 10.2.1 */
121 .blocklen_bytes = 16,
122 .cra_name = "ctr_aes128",
123 .backend_cra_name = "aes",
124 }, {
125 .flags = DRBG_CTR | DRBG_STRENGTH192,
126 .statelen = 40, /* 320 bits as defined in 10.2.1 */
127 .blocklen_bytes = 16,
128 .cra_name = "ctr_aes192",
129 .backend_cra_name = "aes",
130 }, {
131 .flags = DRBG_CTR | DRBG_STRENGTH256,
132 .statelen = 48, /* 384 bits as defined in 10.2.1 */
133 .blocklen_bytes = 16,
134 .cra_name = "ctr_aes256",
135 .backend_cra_name = "aes",
136 },
137 #endif /* CONFIG_CRYPTO_DRBG_CTR */
138 #ifdef CONFIG_CRYPTO_DRBG_HASH
139 {
140 .flags = DRBG_HASH | DRBG_STRENGTH128,
141 .statelen = 55, /* 440 bits */
142 .blocklen_bytes = 20,
143 .cra_name = "sha1",
144 .backend_cra_name = "sha1",
145 }, {
146 .flags = DRBG_HASH | DRBG_STRENGTH256,
147 .statelen = 111, /* 888 bits */
148 .blocklen_bytes = 48,
149 .cra_name = "sha384",
150 .backend_cra_name = "sha384",
151 }, {
152 .flags = DRBG_HASH | DRBG_STRENGTH256,
153 .statelen = 111, /* 888 bits */
154 .blocklen_bytes = 64,
155 .cra_name = "sha512",
156 .backend_cra_name = "sha512",
157 }, {
158 .flags = DRBG_HASH | DRBG_STRENGTH256,
159 .statelen = 55, /* 440 bits */
160 .blocklen_bytes = 32,
161 .cra_name = "sha256",
162 .backend_cra_name = "sha256",
163 },
164 #endif /* CONFIG_CRYPTO_DRBG_HASH */
165 #ifdef CONFIG_CRYPTO_DRBG_HMAC
166 {
167 .flags = DRBG_HMAC | DRBG_STRENGTH128,
168 .statelen = 20, /* block length of cipher */
169 .blocklen_bytes = 20,
170 .cra_name = "hmac_sha1",
171 .backend_cra_name = "hmac(sha1)",
172 }, {
173 .flags = DRBG_HMAC | DRBG_STRENGTH256,
174 .statelen = 48, /* block length of cipher */
175 .blocklen_bytes = 48,
176 .cra_name = "hmac_sha384",
177 .backend_cra_name = "hmac(sha384)",
178 }, {
179 .flags = DRBG_HMAC | DRBG_STRENGTH256,
180 .statelen = 64, /* block length of cipher */
181 .blocklen_bytes = 64,
182 .cra_name = "hmac_sha512",
183 .backend_cra_name = "hmac(sha512)",
184 }, {
185 .flags = DRBG_HMAC | DRBG_STRENGTH256,
186 .statelen = 32, /* block length of cipher */
187 .blocklen_bytes = 32,
188 .cra_name = "hmac_sha256",
189 .backend_cra_name = "hmac(sha256)",
190 },
191 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
192 };
193
194 static int drbg_uninstantiate(struct drbg_state *drbg);
195
196 /******************************************************************
197 * Generic helper functions
198 ******************************************************************/
199
200 /*
201 * Return strength of DRBG according to SP800-90A section 8.4
202 *
203 * @flags DRBG flags reference
204 *
205 * Return: normalized strength in *bytes* value or 32 as default
206 * to counter programming errors
207 */
drbg_sec_strength(drbg_flag_t flags)208 static inline unsigned short drbg_sec_strength(drbg_flag_t flags)
209 {
210 switch (flags & DRBG_STRENGTH_MASK) {
211 case DRBG_STRENGTH128:
212 return 16;
213 case DRBG_STRENGTH192:
214 return 24;
215 case DRBG_STRENGTH256:
216 return 32;
217 default:
218 return 32;
219 }
220 }
221
222 /*
223 * FIPS 140-2 continuous self test for the noise source
224 * The test is performed on the noise source input data. Thus, the function
225 * implicitly knows the size of the buffer to be equal to the security
226 * strength.
227 *
228 * Note, this function disregards the nonce trailing the entropy data during
229 * initial seeding.
230 *
231 * drbg->drbg_mutex must have been taken.
232 *
233 * @drbg DRBG handle
234 * @entropy buffer of seed data to be checked
235 *
236 * return:
237 * 0 on success
238 * -EAGAIN on when the CTRNG is not yet primed
239 * < 0 on error
240 */
drbg_fips_continuous_test(struct drbg_state * drbg,const unsigned char * entropy)241 static int drbg_fips_continuous_test(struct drbg_state *drbg,
242 const unsigned char *entropy)
243 {
244 unsigned short entropylen = drbg_sec_strength(drbg->core->flags);
245 int ret = 0;
246
247 if (!IS_ENABLED(CONFIG_CRYPTO_FIPS))
248 return 0;
249
250 /* skip test if we test the overall system */
251 if (list_empty(&drbg->test_data.list))
252 return 0;
253 /* only perform test in FIPS mode */
254 if (!fips_enabled)
255 return 0;
256
257 if (!drbg->fips_primed) {
258 /* Priming of FIPS test */
259 memcpy(drbg->prev, entropy, entropylen);
260 drbg->fips_primed = true;
261 /* priming: another round is needed */
262 return -EAGAIN;
263 }
264 ret = memcmp(drbg->prev, entropy, entropylen);
265 if (!ret)
266 panic("DRBG continuous self test failed\n");
267 memcpy(drbg->prev, entropy, entropylen);
268
269 /* the test shall pass when the two values are not equal */
270 return 0;
271 }
272
273 /*
274 * Convert an integer into a byte representation of this integer.
275 * The byte representation is big-endian
276 *
277 * @val value to be converted
278 * @buf buffer holding the converted integer -- caller must ensure that
279 * buffer size is at least 32 bit
280 */
281 #if (defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR))
drbg_cpu_to_be32(__u32 val,unsigned char * buf)282 static inline void drbg_cpu_to_be32(__u32 val, unsigned char *buf)
283 {
284 struct s {
285 __be32 conv;
286 };
287 struct s *conversion = (struct s *) buf;
288
289 conversion->conv = cpu_to_be32(val);
290 }
291 #endif /* defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR) */
292
293 /******************************************************************
294 * CTR DRBG callback functions
295 ******************************************************************/
296
297 #ifdef CONFIG_CRYPTO_DRBG_CTR
298 #define CRYPTO_DRBG_CTR_STRING "CTR "
299 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes256");
300 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes256");
301 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes192");
302 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes192");
303 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes128");
304 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes128");
305
306 static void drbg_kcapi_symsetkey(struct drbg_state *drbg,
307 const unsigned char *key);
308 static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
309 const struct drbg_string *in);
310 static int drbg_init_sym_kernel(struct drbg_state *drbg);
311 static int drbg_fini_sym_kernel(struct drbg_state *drbg);
312 static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
313 u8 *inbuf, u32 inbuflen,
314 u8 *outbuf, u32 outlen);
315 #define DRBG_OUTSCRATCHLEN 256
316
317 /* BCC function for CTR DRBG as defined in 10.4.3 */
drbg_ctr_bcc(struct drbg_state * drbg,unsigned char * out,const unsigned char * key,struct list_head * in)318 static int drbg_ctr_bcc(struct drbg_state *drbg,
319 unsigned char *out, const unsigned char *key,
320 struct list_head *in)
321 {
322 int ret = 0;
323 struct drbg_string *curr = NULL;
324 struct drbg_string data;
325 short cnt = 0;
326
327 drbg_string_fill(&data, out, drbg_blocklen(drbg));
328
329 /* 10.4.3 step 2 / 4 */
330 drbg_kcapi_symsetkey(drbg, key);
331 list_for_each_entry(curr, in, list) {
332 const unsigned char *pos = curr->buf;
333 size_t len = curr->len;
334 /* 10.4.3 step 4.1 */
335 while (len) {
336 /* 10.4.3 step 4.2 */
337 if (drbg_blocklen(drbg) == cnt) {
338 cnt = 0;
339 ret = drbg_kcapi_sym(drbg, out, &data);
340 if (ret)
341 return ret;
342 }
343 out[cnt] ^= *pos;
344 pos++;
345 cnt++;
346 len--;
347 }
348 }
349 /* 10.4.3 step 4.2 for last block */
350 if (cnt)
351 ret = drbg_kcapi_sym(drbg, out, &data);
352
353 return ret;
354 }
355
356 /*
357 * scratchpad usage: drbg_ctr_update is interlinked with drbg_ctr_df
358 * (and drbg_ctr_bcc, but this function does not need any temporary buffers),
359 * the scratchpad is used as follows:
360 * drbg_ctr_update:
361 * temp
362 * start: drbg->scratchpad
363 * length: drbg_statelen(drbg) + drbg_blocklen(drbg)
364 * note: the cipher writing into this variable works
365 * blocklen-wise. Now, when the statelen is not a multiple
366 * of blocklen, the generateion loop below "spills over"
367 * by at most blocklen. Thus, we need to give sufficient
368 * memory.
369 * df_data
370 * start: drbg->scratchpad +
371 * drbg_statelen(drbg) + drbg_blocklen(drbg)
372 * length: drbg_statelen(drbg)
373 *
374 * drbg_ctr_df:
375 * pad
376 * start: df_data + drbg_statelen(drbg)
377 * length: drbg_blocklen(drbg)
378 * iv
379 * start: pad + drbg_blocklen(drbg)
380 * length: drbg_blocklen(drbg)
381 * temp
382 * start: iv + drbg_blocklen(drbg)
383 * length: drbg_satelen(drbg) + drbg_blocklen(drbg)
384 * note: temp is the buffer that the BCC function operates
385 * on. BCC operates blockwise. drbg_statelen(drbg)
386 * is sufficient when the DRBG state length is a multiple
387 * of the block size. For AES192 (and maybe other ciphers)
388 * this is not correct and the length for temp is
389 * insufficient (yes, that also means for such ciphers,
390 * the final output of all BCC rounds are truncated).
391 * Therefore, add drbg_blocklen(drbg) to cover all
392 * possibilities.
393 */
394
395 /* Derivation Function for CTR DRBG as defined in 10.4.2 */
drbg_ctr_df(struct drbg_state * drbg,unsigned char * df_data,size_t bytes_to_return,struct list_head * seedlist)396 static int drbg_ctr_df(struct drbg_state *drbg,
397 unsigned char *df_data, size_t bytes_to_return,
398 struct list_head *seedlist)
399 {
400 int ret = -EFAULT;
401 unsigned char L_N[8];
402 /* S3 is input */
403 struct drbg_string S1, S2, S4, cipherin;
404 LIST_HEAD(bcc_list);
405 unsigned char *pad = df_data + drbg_statelen(drbg);
406 unsigned char *iv = pad + drbg_blocklen(drbg);
407 unsigned char *temp = iv + drbg_blocklen(drbg);
408 size_t padlen = 0;
409 unsigned int templen = 0;
410 /* 10.4.2 step 7 */
411 unsigned int i = 0;
412 /* 10.4.2 step 8 */
413 const unsigned char *K = (unsigned char *)
414 "\x00\x01\x02\x03\x04\x05\x06\x07"
415 "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
416 "\x10\x11\x12\x13\x14\x15\x16\x17"
417 "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f";
418 unsigned char *X;
419 size_t generated_len = 0;
420 size_t inputlen = 0;
421 struct drbg_string *seed = NULL;
422
423 memset(pad, 0, drbg_blocklen(drbg));
424 memset(iv, 0, drbg_blocklen(drbg));
425
426 /* 10.4.2 step 1 is implicit as we work byte-wise */
427
428 /* 10.4.2 step 2 */
429 if ((512/8) < bytes_to_return)
430 return -EINVAL;
431
432 /* 10.4.2 step 2 -- calculate the entire length of all input data */
433 list_for_each_entry(seed, seedlist, list)
434 inputlen += seed->len;
435 drbg_cpu_to_be32(inputlen, &L_N[0]);
436
437 /* 10.4.2 step 3 */
438 drbg_cpu_to_be32(bytes_to_return, &L_N[4]);
439
440 /* 10.4.2 step 5: length is L_N, input_string, one byte, padding */
441 padlen = (inputlen + sizeof(L_N) + 1) % (drbg_blocklen(drbg));
442 /* wrap the padlen appropriately */
443 if (padlen)
444 padlen = drbg_blocklen(drbg) - padlen;
445 /*
446 * pad / padlen contains the 0x80 byte and the following zero bytes.
447 * As the calculated padlen value only covers the number of zero
448 * bytes, this value has to be incremented by one for the 0x80 byte.
449 */
450 padlen++;
451 pad[0] = 0x80;
452
453 /* 10.4.2 step 4 -- first fill the linked list and then order it */
454 drbg_string_fill(&S1, iv, drbg_blocklen(drbg));
455 list_add_tail(&S1.list, &bcc_list);
456 drbg_string_fill(&S2, L_N, sizeof(L_N));
457 list_add_tail(&S2.list, &bcc_list);
458 list_splice_tail(seedlist, &bcc_list);
459 drbg_string_fill(&S4, pad, padlen);
460 list_add_tail(&S4.list, &bcc_list);
461
462 /* 10.4.2 step 9 */
463 while (templen < (drbg_keylen(drbg) + (drbg_blocklen(drbg)))) {
464 /*
465 * 10.4.2 step 9.1 - the padding is implicit as the buffer
466 * holds zeros after allocation -- even the increment of i
467 * is irrelevant as the increment remains within length of i
468 */
469 drbg_cpu_to_be32(i, iv);
470 /* 10.4.2 step 9.2 -- BCC and concatenation with temp */
471 ret = drbg_ctr_bcc(drbg, temp + templen, K, &bcc_list);
472 if (ret)
473 goto out;
474 /* 10.4.2 step 9.3 */
475 i++;
476 templen += drbg_blocklen(drbg);
477 }
478
479 /* 10.4.2 step 11 */
480 X = temp + (drbg_keylen(drbg));
481 drbg_string_fill(&cipherin, X, drbg_blocklen(drbg));
482
483 /* 10.4.2 step 12: overwriting of outval is implemented in next step */
484
485 /* 10.4.2 step 13 */
486 drbg_kcapi_symsetkey(drbg, temp);
487 while (generated_len < bytes_to_return) {
488 short blocklen = 0;
489 /*
490 * 10.4.2 step 13.1: the truncation of the key length is
491 * implicit as the key is only drbg_blocklen in size based on
492 * the implementation of the cipher function callback
493 */
494 ret = drbg_kcapi_sym(drbg, X, &cipherin);
495 if (ret)
496 goto out;
497 blocklen = (drbg_blocklen(drbg) <
498 (bytes_to_return - generated_len)) ?
499 drbg_blocklen(drbg) :
500 (bytes_to_return - generated_len);
501 /* 10.4.2 step 13.2 and 14 */
502 memcpy(df_data + generated_len, X, blocklen);
503 generated_len += blocklen;
504 }
505
506 ret = 0;
507
508 out:
509 memset(iv, 0, drbg_blocklen(drbg));
510 memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
511 memset(pad, 0, drbg_blocklen(drbg));
512 return ret;
513 }
514
515 /*
516 * update function of CTR DRBG as defined in 10.2.1.2
517 *
518 * The reseed variable has an enhanced meaning compared to the update
519 * functions of the other DRBGs as follows:
520 * 0 => initial seed from initialization
521 * 1 => reseed via drbg_seed
522 * 2 => first invocation from drbg_ctr_update when addtl is present. In
523 * this case, the df_data scratchpad is not deleted so that it is
524 * available for another calls to prevent calling the DF function
525 * again.
526 * 3 => second invocation from drbg_ctr_update. When the update function
527 * was called with addtl, the df_data memory already contains the
528 * DFed addtl information and we do not need to call DF again.
529 */
drbg_ctr_update(struct drbg_state * drbg,struct list_head * seed,int reseed)530 static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed,
531 int reseed)
532 {
533 int ret = -EFAULT;
534 /* 10.2.1.2 step 1 */
535 unsigned char *temp = drbg->scratchpad;
536 unsigned char *df_data = drbg->scratchpad + drbg_statelen(drbg) +
537 drbg_blocklen(drbg);
538
539 if (3 > reseed)
540 memset(df_data, 0, drbg_statelen(drbg));
541
542 if (!reseed) {
543 /*
544 * The DRBG uses the CTR mode of the underlying AES cipher. The
545 * CTR mode increments the counter value after the AES operation
546 * but SP800-90A requires that the counter is incremented before
547 * the AES operation. Hence, we increment it at the time we set
548 * it by one.
549 */
550 crypto_inc(drbg->V, drbg_blocklen(drbg));
551
552 ret = crypto_skcipher_setkey(drbg->ctr_handle, drbg->C,
553 drbg_keylen(drbg));
554 if (ret)
555 goto out;
556 }
557
558 /* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */
559 if (seed) {
560 ret = drbg_ctr_df(drbg, df_data, drbg_statelen(drbg), seed);
561 if (ret)
562 goto out;
563 }
564
565 ret = drbg_kcapi_sym_ctr(drbg, df_data, drbg_statelen(drbg),
566 temp, drbg_statelen(drbg));
567 if (ret)
568 return ret;
569
570 /* 10.2.1.2 step 5 */
571 ret = crypto_skcipher_setkey(drbg->ctr_handle, temp,
572 drbg_keylen(drbg));
573 if (ret)
574 goto out;
575 /* 10.2.1.2 step 6 */
576 memcpy(drbg->V, temp + drbg_keylen(drbg), drbg_blocklen(drbg));
577 /* See above: increment counter by one to compensate timing of CTR op */
578 crypto_inc(drbg->V, drbg_blocklen(drbg));
579 ret = 0;
580
581 out:
582 memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
583 if (2 != reseed)
584 memset(df_data, 0, drbg_statelen(drbg));
585 return ret;
586 }
587
588 /*
589 * scratchpad use: drbg_ctr_update is called independently from
590 * drbg_ctr_extract_bytes. Therefore, the scratchpad is reused
591 */
592 /* Generate function of CTR DRBG as defined in 10.2.1.5.2 */
drbg_ctr_generate(struct drbg_state * drbg,unsigned char * buf,unsigned int buflen,struct list_head * addtl)593 static int drbg_ctr_generate(struct drbg_state *drbg,
594 unsigned char *buf, unsigned int buflen,
595 struct list_head *addtl)
596 {
597 int ret;
598 int len = min_t(int, buflen, INT_MAX);
599
600 /* 10.2.1.5.2 step 2 */
601 if (addtl && !list_empty(addtl)) {
602 ret = drbg_ctr_update(drbg, addtl, 2);
603 if (ret)
604 return 0;
605 }
606
607 /* 10.2.1.5.2 step 4.1 */
608 ret = drbg_kcapi_sym_ctr(drbg, NULL, 0, buf, len);
609 if (ret)
610 return ret;
611
612 /* 10.2.1.5.2 step 6 */
613 ret = drbg_ctr_update(drbg, NULL, 3);
614 if (ret)
615 len = ret;
616
617 return len;
618 }
619
620 static const struct drbg_state_ops drbg_ctr_ops = {
621 .update = drbg_ctr_update,
622 .generate = drbg_ctr_generate,
623 .crypto_init = drbg_init_sym_kernel,
624 .crypto_fini = drbg_fini_sym_kernel,
625 };
626 #endif /* CONFIG_CRYPTO_DRBG_CTR */
627
628 /******************************************************************
629 * HMAC DRBG callback functions
630 ******************************************************************/
631
632 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
633 static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
634 const struct list_head *in);
635 static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
636 const unsigned char *key);
637 static int drbg_init_hash_kernel(struct drbg_state *drbg);
638 static int drbg_fini_hash_kernel(struct drbg_state *drbg);
639 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
640
641 #ifdef CONFIG_CRYPTO_DRBG_HMAC
642 #define CRYPTO_DRBG_HMAC_STRING "HMAC "
643 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha512");
644 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha512");
645 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha384");
646 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha384");
647 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha256");
648 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha256");
649 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha1");
650 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha1");
651
652 /* update function of HMAC DRBG as defined in 10.1.2.2 */
drbg_hmac_update(struct drbg_state * drbg,struct list_head * seed,int reseed)653 static int drbg_hmac_update(struct drbg_state *drbg, struct list_head *seed,
654 int reseed)
655 {
656 int ret = -EFAULT;
657 int i = 0;
658 struct drbg_string seed1, seed2, vdata;
659 LIST_HEAD(seedlist);
660 LIST_HEAD(vdatalist);
661
662 if (!reseed) {
663 /* 10.1.2.3 step 2 -- memset(0) of C is implicit with kzalloc */
664 memset(drbg->V, 1, drbg_statelen(drbg));
665 drbg_kcapi_hmacsetkey(drbg, drbg->C);
666 }
667
668 drbg_string_fill(&seed1, drbg->V, drbg_statelen(drbg));
669 list_add_tail(&seed1.list, &seedlist);
670 /* buffer of seed2 will be filled in for loop below with one byte */
671 drbg_string_fill(&seed2, NULL, 1);
672 list_add_tail(&seed2.list, &seedlist);
673 /* input data of seed is allowed to be NULL at this point */
674 if (seed)
675 list_splice_tail(seed, &seedlist);
676
677 drbg_string_fill(&vdata, drbg->V, drbg_statelen(drbg));
678 list_add_tail(&vdata.list, &vdatalist);
679 for (i = 2; 0 < i; i--) {
680 /* first round uses 0x0, second 0x1 */
681 unsigned char prefix = DRBG_PREFIX0;
682 if (1 == i)
683 prefix = DRBG_PREFIX1;
684 /* 10.1.2.2 step 1 and 4 -- concatenation and HMAC for key */
685 seed2.buf = &prefix;
686 ret = drbg_kcapi_hash(drbg, drbg->C, &seedlist);
687 if (ret)
688 return ret;
689 drbg_kcapi_hmacsetkey(drbg, drbg->C);
690
691 /* 10.1.2.2 step 2 and 5 -- HMAC for V */
692 ret = drbg_kcapi_hash(drbg, drbg->V, &vdatalist);
693 if (ret)
694 return ret;
695
696 /* 10.1.2.2 step 3 */
697 if (!seed)
698 return ret;
699 }
700
701 return 0;
702 }
703
704 /* generate function of HMAC DRBG as defined in 10.1.2.5 */
drbg_hmac_generate(struct drbg_state * drbg,unsigned char * buf,unsigned int buflen,struct list_head * addtl)705 static int drbg_hmac_generate(struct drbg_state *drbg,
706 unsigned char *buf,
707 unsigned int buflen,
708 struct list_head *addtl)
709 {
710 int len = 0;
711 int ret = 0;
712 struct drbg_string data;
713 LIST_HEAD(datalist);
714
715 /* 10.1.2.5 step 2 */
716 if (addtl && !list_empty(addtl)) {
717 ret = drbg_hmac_update(drbg, addtl, 1);
718 if (ret)
719 return ret;
720 }
721
722 drbg_string_fill(&data, drbg->V, drbg_statelen(drbg));
723 list_add_tail(&data.list, &datalist);
724 while (len < buflen) {
725 unsigned int outlen = 0;
726 /* 10.1.2.5 step 4.1 */
727 ret = drbg_kcapi_hash(drbg, drbg->V, &datalist);
728 if (ret)
729 return ret;
730 outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
731 drbg_blocklen(drbg) : (buflen - len);
732
733 /* 10.1.2.5 step 4.2 */
734 memcpy(buf + len, drbg->V, outlen);
735 len += outlen;
736 }
737
738 /* 10.1.2.5 step 6 */
739 if (addtl && !list_empty(addtl))
740 ret = drbg_hmac_update(drbg, addtl, 1);
741 else
742 ret = drbg_hmac_update(drbg, NULL, 1);
743 if (ret)
744 return ret;
745
746 return len;
747 }
748
749 static const struct drbg_state_ops drbg_hmac_ops = {
750 .update = drbg_hmac_update,
751 .generate = drbg_hmac_generate,
752 .crypto_init = drbg_init_hash_kernel,
753 .crypto_fini = drbg_fini_hash_kernel,
754 };
755 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
756
757 /******************************************************************
758 * Hash DRBG callback functions
759 ******************************************************************/
760
761 #ifdef CONFIG_CRYPTO_DRBG_HASH
762 #define CRYPTO_DRBG_HASH_STRING "HASH "
763 MODULE_ALIAS_CRYPTO("drbg_pr_sha512");
764 MODULE_ALIAS_CRYPTO("drbg_nopr_sha512");
765 MODULE_ALIAS_CRYPTO("drbg_pr_sha384");
766 MODULE_ALIAS_CRYPTO("drbg_nopr_sha384");
767 MODULE_ALIAS_CRYPTO("drbg_pr_sha256");
768 MODULE_ALIAS_CRYPTO("drbg_nopr_sha256");
769 MODULE_ALIAS_CRYPTO("drbg_pr_sha1");
770 MODULE_ALIAS_CRYPTO("drbg_nopr_sha1");
771
772 /*
773 * Increment buffer
774 *
775 * @dst buffer to increment
776 * @add value to add
777 */
drbg_add_buf(unsigned char * dst,size_t dstlen,const unsigned char * add,size_t addlen)778 static inline void drbg_add_buf(unsigned char *dst, size_t dstlen,
779 const unsigned char *add, size_t addlen)
780 {
781 /* implied: dstlen > addlen */
782 unsigned char *dstptr;
783 const unsigned char *addptr;
784 unsigned int remainder = 0;
785 size_t len = addlen;
786
787 dstptr = dst + (dstlen-1);
788 addptr = add + (addlen-1);
789 while (len) {
790 remainder += *dstptr + *addptr;
791 *dstptr = remainder & 0xff;
792 remainder >>= 8;
793 len--; dstptr--; addptr--;
794 }
795 len = dstlen - addlen;
796 while (len && remainder > 0) {
797 remainder = *dstptr + 1;
798 *dstptr = remainder & 0xff;
799 remainder >>= 8;
800 len--; dstptr--;
801 }
802 }
803
804 /*
805 * scratchpad usage: as drbg_hash_update and drbg_hash_df are used
806 * interlinked, the scratchpad is used as follows:
807 * drbg_hash_update
808 * start: drbg->scratchpad
809 * length: drbg_statelen(drbg)
810 * drbg_hash_df:
811 * start: drbg->scratchpad + drbg_statelen(drbg)
812 * length: drbg_blocklen(drbg)
813 *
814 * drbg_hash_process_addtl uses the scratchpad, but fully completes
815 * before either of the functions mentioned before are invoked. Therefore,
816 * drbg_hash_process_addtl does not need to be specifically considered.
817 */
818
819 /* Derivation Function for Hash DRBG as defined in 10.4.1 */
drbg_hash_df(struct drbg_state * drbg,unsigned char * outval,size_t outlen,struct list_head * entropylist)820 static int drbg_hash_df(struct drbg_state *drbg,
821 unsigned char *outval, size_t outlen,
822 struct list_head *entropylist)
823 {
824 int ret = 0;
825 size_t len = 0;
826 unsigned char input[5];
827 unsigned char *tmp = drbg->scratchpad + drbg_statelen(drbg);
828 struct drbg_string data;
829
830 /* 10.4.1 step 3 */
831 input[0] = 1;
832 drbg_cpu_to_be32((outlen * 8), &input[1]);
833
834 /* 10.4.1 step 4.1 -- concatenation of data for input into hash */
835 drbg_string_fill(&data, input, 5);
836 list_add(&data.list, entropylist);
837
838 /* 10.4.1 step 4 */
839 while (len < outlen) {
840 short blocklen = 0;
841 /* 10.4.1 step 4.1 */
842 ret = drbg_kcapi_hash(drbg, tmp, entropylist);
843 if (ret)
844 goto out;
845 /* 10.4.1 step 4.2 */
846 input[0]++;
847 blocklen = (drbg_blocklen(drbg) < (outlen - len)) ?
848 drbg_blocklen(drbg) : (outlen - len);
849 memcpy(outval + len, tmp, blocklen);
850 len += blocklen;
851 }
852
853 out:
854 memset(tmp, 0, drbg_blocklen(drbg));
855 return ret;
856 }
857
858 /* update function for Hash DRBG as defined in 10.1.1.2 / 10.1.1.3 */
drbg_hash_update(struct drbg_state * drbg,struct list_head * seed,int reseed)859 static int drbg_hash_update(struct drbg_state *drbg, struct list_head *seed,
860 int reseed)
861 {
862 int ret = 0;
863 struct drbg_string data1, data2;
864 LIST_HEAD(datalist);
865 LIST_HEAD(datalist2);
866 unsigned char *V = drbg->scratchpad;
867 unsigned char prefix = DRBG_PREFIX1;
868
869 if (!seed)
870 return -EINVAL;
871
872 if (reseed) {
873 /* 10.1.1.3 step 1 */
874 memcpy(V, drbg->V, drbg_statelen(drbg));
875 drbg_string_fill(&data1, &prefix, 1);
876 list_add_tail(&data1.list, &datalist);
877 drbg_string_fill(&data2, V, drbg_statelen(drbg));
878 list_add_tail(&data2.list, &datalist);
879 }
880 list_splice_tail(seed, &datalist);
881
882 /* 10.1.1.2 / 10.1.1.3 step 2 and 3 */
883 ret = drbg_hash_df(drbg, drbg->V, drbg_statelen(drbg), &datalist);
884 if (ret)
885 goto out;
886
887 /* 10.1.1.2 / 10.1.1.3 step 4 */
888 prefix = DRBG_PREFIX0;
889 drbg_string_fill(&data1, &prefix, 1);
890 list_add_tail(&data1.list, &datalist2);
891 drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
892 list_add_tail(&data2.list, &datalist2);
893 /* 10.1.1.2 / 10.1.1.3 step 4 */
894 ret = drbg_hash_df(drbg, drbg->C, drbg_statelen(drbg), &datalist2);
895
896 out:
897 memset(drbg->scratchpad, 0, drbg_statelen(drbg));
898 return ret;
899 }
900
901 /* processing of additional information string for Hash DRBG */
drbg_hash_process_addtl(struct drbg_state * drbg,struct list_head * addtl)902 static int drbg_hash_process_addtl(struct drbg_state *drbg,
903 struct list_head *addtl)
904 {
905 int ret = 0;
906 struct drbg_string data1, data2;
907 LIST_HEAD(datalist);
908 unsigned char prefix = DRBG_PREFIX2;
909
910 /* 10.1.1.4 step 2 */
911 if (!addtl || list_empty(addtl))
912 return 0;
913
914 /* 10.1.1.4 step 2a */
915 drbg_string_fill(&data1, &prefix, 1);
916 drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
917 list_add_tail(&data1.list, &datalist);
918 list_add_tail(&data2.list, &datalist);
919 list_splice_tail(addtl, &datalist);
920 ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
921 if (ret)
922 goto out;
923
924 /* 10.1.1.4 step 2b */
925 drbg_add_buf(drbg->V, drbg_statelen(drbg),
926 drbg->scratchpad, drbg_blocklen(drbg));
927
928 out:
929 memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
930 return ret;
931 }
932
933 /* Hashgen defined in 10.1.1.4 */
drbg_hash_hashgen(struct drbg_state * drbg,unsigned char * buf,unsigned int buflen)934 static int drbg_hash_hashgen(struct drbg_state *drbg,
935 unsigned char *buf,
936 unsigned int buflen)
937 {
938 int len = 0;
939 int ret = 0;
940 unsigned char *src = drbg->scratchpad;
941 unsigned char *dst = drbg->scratchpad + drbg_statelen(drbg);
942 struct drbg_string data;
943 LIST_HEAD(datalist);
944
945 /* 10.1.1.4 step hashgen 2 */
946 memcpy(src, drbg->V, drbg_statelen(drbg));
947
948 drbg_string_fill(&data, src, drbg_statelen(drbg));
949 list_add_tail(&data.list, &datalist);
950 while (len < buflen) {
951 unsigned int outlen = 0;
952 /* 10.1.1.4 step hashgen 4.1 */
953 ret = drbg_kcapi_hash(drbg, dst, &datalist);
954 if (ret) {
955 len = ret;
956 goto out;
957 }
958 outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
959 drbg_blocklen(drbg) : (buflen - len);
960 /* 10.1.1.4 step hashgen 4.2 */
961 memcpy(buf + len, dst, outlen);
962 len += outlen;
963 /* 10.1.1.4 hashgen step 4.3 */
964 if (len < buflen)
965 crypto_inc(src, drbg_statelen(drbg));
966 }
967
968 out:
969 memset(drbg->scratchpad, 0,
970 (drbg_statelen(drbg) + drbg_blocklen(drbg)));
971 return len;
972 }
973
974 /* generate function for Hash DRBG as defined in 10.1.1.4 */
drbg_hash_generate(struct drbg_state * drbg,unsigned char * buf,unsigned int buflen,struct list_head * addtl)975 static int drbg_hash_generate(struct drbg_state *drbg,
976 unsigned char *buf, unsigned int buflen,
977 struct list_head *addtl)
978 {
979 int len = 0;
980 int ret = 0;
981 union {
982 unsigned char req[8];
983 __be64 req_int;
984 } u;
985 unsigned char prefix = DRBG_PREFIX3;
986 struct drbg_string data1, data2;
987 LIST_HEAD(datalist);
988
989 /* 10.1.1.4 step 2 */
990 ret = drbg_hash_process_addtl(drbg, addtl);
991 if (ret)
992 return ret;
993 /* 10.1.1.4 step 3 */
994 len = drbg_hash_hashgen(drbg, buf, buflen);
995
996 /* this is the value H as documented in 10.1.1.4 */
997 /* 10.1.1.4 step 4 */
998 drbg_string_fill(&data1, &prefix, 1);
999 list_add_tail(&data1.list, &datalist);
1000 drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
1001 list_add_tail(&data2.list, &datalist);
1002 ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
1003 if (ret) {
1004 len = ret;
1005 goto out;
1006 }
1007
1008 /* 10.1.1.4 step 5 */
1009 drbg_add_buf(drbg->V, drbg_statelen(drbg),
1010 drbg->scratchpad, drbg_blocklen(drbg));
1011 drbg_add_buf(drbg->V, drbg_statelen(drbg),
1012 drbg->C, drbg_statelen(drbg));
1013 u.req_int = cpu_to_be64(drbg->reseed_ctr);
1014 drbg_add_buf(drbg->V, drbg_statelen(drbg), u.req, 8);
1015
1016 out:
1017 memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
1018 return len;
1019 }
1020
1021 /*
1022 * scratchpad usage: as update and generate are used isolated, both
1023 * can use the scratchpad
1024 */
1025 static const struct drbg_state_ops drbg_hash_ops = {
1026 .update = drbg_hash_update,
1027 .generate = drbg_hash_generate,
1028 .crypto_init = drbg_init_hash_kernel,
1029 .crypto_fini = drbg_fini_hash_kernel,
1030 };
1031 #endif /* CONFIG_CRYPTO_DRBG_HASH */
1032
1033 /******************************************************************
1034 * Functions common for DRBG implementations
1035 ******************************************************************/
1036
__drbg_seed(struct drbg_state * drbg,struct list_head * seed,int reseed)1037 static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed,
1038 int reseed)
1039 {
1040 int ret = drbg->d_ops->update(drbg, seed, reseed);
1041
1042 if (ret)
1043 return ret;
1044
1045 drbg->seeded = true;
1046 /* 10.1.1.2 / 10.1.1.3 step 5 */
1047 drbg->reseed_ctr = 1;
1048
1049 return ret;
1050 }
1051
drbg_get_random_bytes(struct drbg_state * drbg,unsigned char * entropy,unsigned int entropylen)1052 static inline int drbg_get_random_bytes(struct drbg_state *drbg,
1053 unsigned char *entropy,
1054 unsigned int entropylen)
1055 {
1056 int ret;
1057
1058 do {
1059 get_random_bytes(entropy, entropylen);
1060 ret = drbg_fips_continuous_test(drbg, entropy);
1061 if (ret && ret != -EAGAIN)
1062 return ret;
1063 } while (ret);
1064
1065 return 0;
1066 }
1067
drbg_async_seed(struct work_struct * work)1068 static void drbg_async_seed(struct work_struct *work)
1069 {
1070 struct drbg_string data;
1071 LIST_HEAD(seedlist);
1072 struct drbg_state *drbg = container_of(work, struct drbg_state,
1073 seed_work);
1074 unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
1075 unsigned char entropy[32];
1076 int ret;
1077
1078 BUG_ON(!entropylen);
1079 BUG_ON(entropylen > sizeof(entropy));
1080
1081 drbg_string_fill(&data, entropy, entropylen);
1082 list_add_tail(&data.list, &seedlist);
1083
1084 mutex_lock(&drbg->drbg_mutex);
1085
1086 ret = drbg_get_random_bytes(drbg, entropy, entropylen);
1087 if (ret)
1088 goto unlock;
1089
1090 /* If nonblocking pool is initialized, deactivate Jitter RNG */
1091 crypto_free_rng(drbg->jent);
1092 drbg->jent = NULL;
1093
1094 /* Set seeded to false so that if __drbg_seed fails the
1095 * next generate call will trigger a reseed.
1096 */
1097 drbg->seeded = false;
1098
1099 __drbg_seed(drbg, &seedlist, true);
1100
1101 if (drbg->seeded)
1102 drbg->reseed_threshold = drbg_max_requests(drbg);
1103
1104 unlock:
1105 mutex_unlock(&drbg->drbg_mutex);
1106
1107 memzero_explicit(entropy, entropylen);
1108 }
1109
1110 /*
1111 * Seeding or reseeding of the DRBG
1112 *
1113 * @drbg: DRBG state struct
1114 * @pers: personalization / additional information buffer
1115 * @reseed: 0 for initial seed process, 1 for reseeding
1116 *
1117 * return:
1118 * 0 on success
1119 * error value otherwise
1120 */
drbg_seed(struct drbg_state * drbg,struct drbg_string * pers,bool reseed)1121 static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
1122 bool reseed)
1123 {
1124 int ret;
1125 unsigned char entropy[((32 + 16) * 2)];
1126 unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
1127 struct drbg_string data1;
1128 LIST_HEAD(seedlist);
1129
1130 /* 9.1 / 9.2 / 9.3.1 step 3 */
1131 if (pers && pers->len > (drbg_max_addtl(drbg))) {
1132 pr_devel("DRBG: personalization string too long %zu\n",
1133 pers->len);
1134 return -EINVAL;
1135 }
1136
1137 if (list_empty(&drbg->test_data.list)) {
1138 drbg_string_fill(&data1, drbg->test_data.buf,
1139 drbg->test_data.len);
1140 pr_devel("DRBG: using test entropy\n");
1141 } else {
1142 /*
1143 * Gather entropy equal to the security strength of the DRBG.
1144 * With a derivation function, a nonce is required in addition
1145 * to the entropy. A nonce must be at least 1/2 of the security
1146 * strength of the DRBG in size. Thus, entropy + nonce is 3/2
1147 * of the strength. The consideration of a nonce is only
1148 * applicable during initial seeding.
1149 */
1150 BUG_ON(!entropylen);
1151 if (!reseed)
1152 entropylen = ((entropylen + 1) / 2) * 3;
1153 BUG_ON((entropylen * 2) > sizeof(entropy));
1154
1155 /* Get seed from in-kernel /dev/urandom */
1156 ret = drbg_get_random_bytes(drbg, entropy, entropylen);
1157 if (ret)
1158 goto out;
1159
1160 if (!drbg->jent) {
1161 drbg_string_fill(&data1, entropy, entropylen);
1162 pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
1163 entropylen);
1164 } else {
1165 /* Get seed from Jitter RNG */
1166 ret = crypto_rng_get_bytes(drbg->jent,
1167 entropy + entropylen,
1168 entropylen);
1169 if (ret) {
1170 pr_devel("DRBG: jent failed with %d\n", ret);
1171 goto out;
1172 }
1173
1174 drbg_string_fill(&data1, entropy, entropylen * 2);
1175 pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
1176 entropylen * 2);
1177 }
1178 }
1179 list_add_tail(&data1.list, &seedlist);
1180
1181 /*
1182 * concatenation of entropy with personalization str / addtl input)
1183 * the variable pers is directly handed in by the caller, so check its
1184 * contents whether it is appropriate
1185 */
1186 if (pers && pers->buf && 0 < pers->len) {
1187 list_add_tail(&pers->list, &seedlist);
1188 pr_devel("DRBG: using personalization string\n");
1189 }
1190
1191 if (!reseed) {
1192 memset(drbg->V, 0, drbg_statelen(drbg));
1193 memset(drbg->C, 0, drbg_statelen(drbg));
1194 }
1195
1196 ret = __drbg_seed(drbg, &seedlist, reseed);
1197
1198 out:
1199 memzero_explicit(entropy, entropylen * 2);
1200
1201 return ret;
1202 }
1203
1204 /* Free all substructures in a DRBG state without the DRBG state structure */
drbg_dealloc_state(struct drbg_state * drbg)1205 static inline void drbg_dealloc_state(struct drbg_state *drbg)
1206 {
1207 if (!drbg)
1208 return;
1209 kzfree(drbg->Vbuf);
1210 drbg->Vbuf = NULL;
1211 drbg->V = NULL;
1212 kzfree(drbg->Cbuf);
1213 drbg->Cbuf = NULL;
1214 drbg->C = NULL;
1215 kzfree(drbg->scratchpadbuf);
1216 drbg->scratchpadbuf = NULL;
1217 drbg->reseed_ctr = 0;
1218 drbg->d_ops = NULL;
1219 drbg->core = NULL;
1220 if (IS_ENABLED(CONFIG_CRYPTO_FIPS)) {
1221 kzfree(drbg->prev);
1222 drbg->prev = NULL;
1223 drbg->fips_primed = false;
1224 }
1225 }
1226
1227 /*
1228 * Allocate all sub-structures for a DRBG state.
1229 * The DRBG state structure must already be allocated.
1230 */
drbg_alloc_state(struct drbg_state * drbg)1231 static inline int drbg_alloc_state(struct drbg_state *drbg)
1232 {
1233 int ret = -ENOMEM;
1234 unsigned int sb_size = 0;
1235
1236 switch (drbg->core->flags & DRBG_TYPE_MASK) {
1237 #ifdef CONFIG_CRYPTO_DRBG_HMAC
1238 case DRBG_HMAC:
1239 drbg->d_ops = &drbg_hmac_ops;
1240 break;
1241 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
1242 #ifdef CONFIG_CRYPTO_DRBG_HASH
1243 case DRBG_HASH:
1244 drbg->d_ops = &drbg_hash_ops;
1245 break;
1246 #endif /* CONFIG_CRYPTO_DRBG_HASH */
1247 #ifdef CONFIG_CRYPTO_DRBG_CTR
1248 case DRBG_CTR:
1249 drbg->d_ops = &drbg_ctr_ops;
1250 break;
1251 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1252 default:
1253 ret = -EOPNOTSUPP;
1254 goto err;
1255 }
1256
1257 ret = drbg->d_ops->crypto_init(drbg);
1258 if (ret < 0)
1259 goto err;
1260
1261 drbg->Vbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL);
1262 if (!drbg->Vbuf) {
1263 ret = -ENOMEM;
1264 goto fini;
1265 }
1266 drbg->V = PTR_ALIGN(drbg->Vbuf, ret + 1);
1267 drbg->Cbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL);
1268 if (!drbg->Cbuf) {
1269 ret = -ENOMEM;
1270 goto fini;
1271 }
1272 drbg->C = PTR_ALIGN(drbg->Cbuf, ret + 1);
1273 /* scratchpad is only generated for CTR and Hash */
1274 if (drbg->core->flags & DRBG_HMAC)
1275 sb_size = 0;
1276 else if (drbg->core->flags & DRBG_CTR)
1277 sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg) + /* temp */
1278 drbg_statelen(drbg) + /* df_data */
1279 drbg_blocklen(drbg) + /* pad */
1280 drbg_blocklen(drbg) + /* iv */
1281 drbg_statelen(drbg) + drbg_blocklen(drbg); /* temp */
1282 else
1283 sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg);
1284
1285 if (0 < sb_size) {
1286 drbg->scratchpadbuf = kzalloc(sb_size + ret, GFP_KERNEL);
1287 if (!drbg->scratchpadbuf) {
1288 ret = -ENOMEM;
1289 goto fini;
1290 }
1291 drbg->scratchpad = PTR_ALIGN(drbg->scratchpadbuf, ret + 1);
1292 }
1293
1294 if (IS_ENABLED(CONFIG_CRYPTO_FIPS)) {
1295 drbg->prev = kzalloc(drbg_sec_strength(drbg->core->flags),
1296 GFP_KERNEL);
1297 if (!drbg->prev)
1298 goto fini;
1299 drbg->fips_primed = false;
1300 }
1301
1302 return 0;
1303
1304 fini:
1305 drbg->d_ops->crypto_fini(drbg);
1306 err:
1307 drbg_dealloc_state(drbg);
1308 return ret;
1309 }
1310
1311 /*************************************************************************
1312 * DRBG interface functions
1313 *************************************************************************/
1314
1315 /*
1316 * DRBG generate function as required by SP800-90A - this function
1317 * generates random numbers
1318 *
1319 * @drbg DRBG state handle
1320 * @buf Buffer where to store the random numbers -- the buffer must already
1321 * be pre-allocated by caller
1322 * @buflen Length of output buffer - this value defines the number of random
1323 * bytes pulled from DRBG
1324 * @addtl Additional input that is mixed into state, may be NULL -- note
1325 * the entropy is pulled by the DRBG internally unconditionally
1326 * as defined in SP800-90A. The additional input is mixed into
1327 * the state in addition to the pulled entropy.
1328 *
1329 * return: 0 when all bytes are generated; < 0 in case of an error
1330 */
drbg_generate(struct drbg_state * drbg,unsigned char * buf,unsigned int buflen,struct drbg_string * addtl)1331 static int drbg_generate(struct drbg_state *drbg,
1332 unsigned char *buf, unsigned int buflen,
1333 struct drbg_string *addtl)
1334 {
1335 int len = 0;
1336 LIST_HEAD(addtllist);
1337
1338 if (!drbg->core) {
1339 pr_devel("DRBG: not yet seeded\n");
1340 return -EINVAL;
1341 }
1342 if (0 == buflen || !buf) {
1343 pr_devel("DRBG: no output buffer provided\n");
1344 return -EINVAL;
1345 }
1346 if (addtl && NULL == addtl->buf && 0 < addtl->len) {
1347 pr_devel("DRBG: wrong format of additional information\n");
1348 return -EINVAL;
1349 }
1350
1351 /* 9.3.1 step 2 */
1352 len = -EINVAL;
1353 if (buflen > (drbg_max_request_bytes(drbg))) {
1354 pr_devel("DRBG: requested random numbers too large %u\n",
1355 buflen);
1356 goto err;
1357 }
1358
1359 /* 9.3.1 step 3 is implicit with the chosen DRBG */
1360
1361 /* 9.3.1 step 4 */
1362 if (addtl && addtl->len > (drbg_max_addtl(drbg))) {
1363 pr_devel("DRBG: additional information string too long %zu\n",
1364 addtl->len);
1365 goto err;
1366 }
1367 /* 9.3.1 step 5 is implicit with the chosen DRBG */
1368
1369 /*
1370 * 9.3.1 step 6 and 9 supplemented by 9.3.2 step c is implemented
1371 * here. The spec is a bit convoluted here, we make it simpler.
1372 */
1373 if (drbg->reseed_threshold < drbg->reseed_ctr)
1374 drbg->seeded = false;
1375
1376 if (drbg->pr || !drbg->seeded) {
1377 pr_devel("DRBG: reseeding before generation (prediction "
1378 "resistance: %s, state %s)\n",
1379 drbg->pr ? "true" : "false",
1380 drbg->seeded ? "seeded" : "unseeded");
1381 /* 9.3.1 steps 7.1 through 7.3 */
1382 len = drbg_seed(drbg, addtl, true);
1383 if (len)
1384 goto err;
1385 /* 9.3.1 step 7.4 */
1386 addtl = NULL;
1387 }
1388
1389 if (addtl && 0 < addtl->len)
1390 list_add_tail(&addtl->list, &addtllist);
1391 /* 9.3.1 step 8 and 10 */
1392 len = drbg->d_ops->generate(drbg, buf, buflen, &addtllist);
1393
1394 /* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */
1395 drbg->reseed_ctr++;
1396 if (0 >= len)
1397 goto err;
1398
1399 /*
1400 * Section 11.3.3 requires to re-perform self tests after some
1401 * generated random numbers. The chosen value after which self
1402 * test is performed is arbitrary, but it should be reasonable.
1403 * However, we do not perform the self tests because of the following
1404 * reasons: it is mathematically impossible that the initial self tests
1405 * were successfully and the following are not. If the initial would
1406 * pass and the following would not, the kernel integrity is violated.
1407 * In this case, the entire kernel operation is questionable and it
1408 * is unlikely that the integrity violation only affects the
1409 * correct operation of the DRBG.
1410 *
1411 * Albeit the following code is commented out, it is provided in
1412 * case somebody has a need to implement the test of 11.3.3.
1413 */
1414 #if 0
1415 if (drbg->reseed_ctr && !(drbg->reseed_ctr % 4096)) {
1416 int err = 0;
1417 pr_devel("DRBG: start to perform self test\n");
1418 if (drbg->core->flags & DRBG_HMAC)
1419 err = alg_test("drbg_pr_hmac_sha256",
1420 "drbg_pr_hmac_sha256", 0, 0);
1421 else if (drbg->core->flags & DRBG_CTR)
1422 err = alg_test("drbg_pr_ctr_aes128",
1423 "drbg_pr_ctr_aes128", 0, 0);
1424 else
1425 err = alg_test("drbg_pr_sha256",
1426 "drbg_pr_sha256", 0, 0);
1427 if (err) {
1428 pr_err("DRBG: periodical self test failed\n");
1429 /*
1430 * uninstantiate implies that from now on, only errors
1431 * are returned when reusing this DRBG cipher handle
1432 */
1433 drbg_uninstantiate(drbg);
1434 return 0;
1435 } else {
1436 pr_devel("DRBG: self test successful\n");
1437 }
1438 }
1439 #endif
1440
1441 /*
1442 * All operations were successful, return 0 as mandated by
1443 * the kernel crypto API interface.
1444 */
1445 len = 0;
1446 err:
1447 return len;
1448 }
1449
1450 /*
1451 * Wrapper around drbg_generate which can pull arbitrary long strings
1452 * from the DRBG without hitting the maximum request limitation.
1453 *
1454 * Parameters: see drbg_generate
1455 * Return codes: see drbg_generate -- if one drbg_generate request fails,
1456 * the entire drbg_generate_long request fails
1457 */
drbg_generate_long(struct drbg_state * drbg,unsigned char * buf,unsigned int buflen,struct drbg_string * addtl)1458 static int drbg_generate_long(struct drbg_state *drbg,
1459 unsigned char *buf, unsigned int buflen,
1460 struct drbg_string *addtl)
1461 {
1462 unsigned int len = 0;
1463 unsigned int slice = 0;
1464 do {
1465 int err = 0;
1466 unsigned int chunk = 0;
1467 slice = ((buflen - len) / drbg_max_request_bytes(drbg));
1468 chunk = slice ? drbg_max_request_bytes(drbg) : (buflen - len);
1469 mutex_lock(&drbg->drbg_mutex);
1470 err = drbg_generate(drbg, buf + len, chunk, addtl);
1471 mutex_unlock(&drbg->drbg_mutex);
1472 if (0 > err)
1473 return err;
1474 len += chunk;
1475 } while (slice > 0 && (len < buflen));
1476 return 0;
1477 }
1478
drbg_schedule_async_seed(struct random_ready_callback * rdy)1479 static void drbg_schedule_async_seed(struct random_ready_callback *rdy)
1480 {
1481 struct drbg_state *drbg = container_of(rdy, struct drbg_state,
1482 random_ready);
1483
1484 schedule_work(&drbg->seed_work);
1485 }
1486
drbg_prepare_hrng(struct drbg_state * drbg)1487 static int drbg_prepare_hrng(struct drbg_state *drbg)
1488 {
1489 int err;
1490
1491 /* We do not need an HRNG in test mode. */
1492 if (list_empty(&drbg->test_data.list))
1493 return 0;
1494
1495 INIT_WORK(&drbg->seed_work, drbg_async_seed);
1496
1497 drbg->random_ready.owner = THIS_MODULE;
1498 drbg->random_ready.func = drbg_schedule_async_seed;
1499
1500 err = add_random_ready_callback(&drbg->random_ready);
1501
1502 switch (err) {
1503 case 0:
1504 break;
1505
1506 case -EALREADY:
1507 err = 0;
1508 /* fall through */
1509
1510 default:
1511 drbg->random_ready.func = NULL;
1512 return err;
1513 }
1514
1515 drbg->jent = crypto_alloc_rng("jitterentropy_rng", 0, 0);
1516
1517 /*
1518 * Require frequent reseeds until the seed source is fully
1519 * initialized.
1520 */
1521 drbg->reseed_threshold = 50;
1522
1523 return err;
1524 }
1525
1526 /*
1527 * DRBG instantiation function as required by SP800-90A - this function
1528 * sets up the DRBG handle, performs the initial seeding and all sanity
1529 * checks required by SP800-90A
1530 *
1531 * @drbg memory of state -- if NULL, new memory is allocated
1532 * @pers Personalization string that is mixed into state, may be NULL -- note
1533 * the entropy is pulled by the DRBG internally unconditionally
1534 * as defined in SP800-90A. The additional input is mixed into
1535 * the state in addition to the pulled entropy.
1536 * @coreref reference to core
1537 * @pr prediction resistance enabled
1538 *
1539 * return
1540 * 0 on success
1541 * error value otherwise
1542 */
drbg_instantiate(struct drbg_state * drbg,struct drbg_string * pers,int coreref,bool pr)1543 static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers,
1544 int coreref, bool pr)
1545 {
1546 int ret;
1547 bool reseed = true;
1548
1549 pr_devel("DRBG: Initializing DRBG core %d with prediction resistance "
1550 "%s\n", coreref, pr ? "enabled" : "disabled");
1551 mutex_lock(&drbg->drbg_mutex);
1552
1553 /* 9.1 step 1 is implicit with the selected DRBG type */
1554
1555 /*
1556 * 9.1 step 2 is implicit as caller can select prediction resistance
1557 * and the flag is copied into drbg->flags --
1558 * all DRBG types support prediction resistance
1559 */
1560
1561 /* 9.1 step 4 is implicit in drbg_sec_strength */
1562
1563 if (!drbg->core) {
1564 drbg->core = &drbg_cores[coreref];
1565 drbg->pr = pr;
1566 drbg->seeded = false;
1567 drbg->reseed_threshold = drbg_max_requests(drbg);
1568
1569 ret = drbg_alloc_state(drbg);
1570 if (ret)
1571 goto unlock;
1572
1573 ret = drbg_prepare_hrng(drbg);
1574 if (ret)
1575 goto free_everything;
1576
1577 if (IS_ERR(drbg->jent)) {
1578 ret = PTR_ERR(drbg->jent);
1579 drbg->jent = NULL;
1580 if (fips_enabled || ret != -ENOENT)
1581 goto free_everything;
1582 pr_info("DRBG: Continuing without Jitter RNG\n");
1583 }
1584
1585 reseed = false;
1586 }
1587
1588 ret = drbg_seed(drbg, pers, reseed);
1589
1590 if (ret && !reseed)
1591 goto free_everything;
1592
1593 mutex_unlock(&drbg->drbg_mutex);
1594 return ret;
1595
1596 unlock:
1597 mutex_unlock(&drbg->drbg_mutex);
1598 return ret;
1599
1600 free_everything:
1601 mutex_unlock(&drbg->drbg_mutex);
1602 drbg_uninstantiate(drbg);
1603 return ret;
1604 }
1605
1606 /*
1607 * DRBG uninstantiate function as required by SP800-90A - this function
1608 * frees all buffers and the DRBG handle
1609 *
1610 * @drbg DRBG state handle
1611 *
1612 * return
1613 * 0 on success
1614 */
drbg_uninstantiate(struct drbg_state * drbg)1615 static int drbg_uninstantiate(struct drbg_state *drbg)
1616 {
1617 if (drbg->random_ready.func) {
1618 del_random_ready_callback(&drbg->random_ready);
1619 cancel_work_sync(&drbg->seed_work);
1620 crypto_free_rng(drbg->jent);
1621 drbg->jent = NULL;
1622 }
1623
1624 if (drbg->d_ops)
1625 drbg->d_ops->crypto_fini(drbg);
1626 drbg_dealloc_state(drbg);
1627 /* no scrubbing of test_data -- this shall survive an uninstantiate */
1628 return 0;
1629 }
1630
1631 /*
1632 * Helper function for setting the test data in the DRBG
1633 *
1634 * @drbg DRBG state handle
1635 * @data test data
1636 * @len test data length
1637 */
drbg_kcapi_set_entropy(struct crypto_rng * tfm,const u8 * data,unsigned int len)1638 static void drbg_kcapi_set_entropy(struct crypto_rng *tfm,
1639 const u8 *data, unsigned int len)
1640 {
1641 struct drbg_state *drbg = crypto_rng_ctx(tfm);
1642
1643 mutex_lock(&drbg->drbg_mutex);
1644 drbg_string_fill(&drbg->test_data, data, len);
1645 mutex_unlock(&drbg->drbg_mutex);
1646 }
1647
1648 /***************************************************************
1649 * Kernel crypto API cipher invocations requested by DRBG
1650 ***************************************************************/
1651
1652 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
1653 struct sdesc {
1654 struct shash_desc shash;
1655 char ctx[];
1656 };
1657
drbg_init_hash_kernel(struct drbg_state * drbg)1658 static int drbg_init_hash_kernel(struct drbg_state *drbg)
1659 {
1660 struct sdesc *sdesc;
1661 struct crypto_shash *tfm;
1662
1663 tfm = crypto_alloc_shash(drbg->core->backend_cra_name, 0, 0);
1664 if (IS_ERR(tfm)) {
1665 pr_info("DRBG: could not allocate digest TFM handle: %s\n",
1666 drbg->core->backend_cra_name);
1667 return PTR_ERR(tfm);
1668 }
1669 BUG_ON(drbg_blocklen(drbg) != crypto_shash_digestsize(tfm));
1670 sdesc = kzalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm),
1671 GFP_KERNEL);
1672 if (!sdesc) {
1673 crypto_free_shash(tfm);
1674 return -ENOMEM;
1675 }
1676
1677 sdesc->shash.tfm = tfm;
1678 drbg->priv_data = sdesc;
1679
1680 return crypto_shash_alignmask(tfm);
1681 }
1682
drbg_fini_hash_kernel(struct drbg_state * drbg)1683 static int drbg_fini_hash_kernel(struct drbg_state *drbg)
1684 {
1685 struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1686 if (sdesc) {
1687 crypto_free_shash(sdesc->shash.tfm);
1688 kzfree(sdesc);
1689 }
1690 drbg->priv_data = NULL;
1691 return 0;
1692 }
1693
drbg_kcapi_hmacsetkey(struct drbg_state * drbg,const unsigned char * key)1694 static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
1695 const unsigned char *key)
1696 {
1697 struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1698
1699 crypto_shash_setkey(sdesc->shash.tfm, key, drbg_statelen(drbg));
1700 }
1701
drbg_kcapi_hash(struct drbg_state * drbg,unsigned char * outval,const struct list_head * in)1702 static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
1703 const struct list_head *in)
1704 {
1705 struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1706 struct drbg_string *input = NULL;
1707
1708 crypto_shash_init(&sdesc->shash);
1709 list_for_each_entry(input, in, list)
1710 crypto_shash_update(&sdesc->shash, input->buf, input->len);
1711 return crypto_shash_final(&sdesc->shash, outval);
1712 }
1713 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
1714
1715 #ifdef CONFIG_CRYPTO_DRBG_CTR
drbg_fini_sym_kernel(struct drbg_state * drbg)1716 static int drbg_fini_sym_kernel(struct drbg_state *drbg)
1717 {
1718 struct crypto_cipher *tfm =
1719 (struct crypto_cipher *)drbg->priv_data;
1720 if (tfm)
1721 crypto_free_cipher(tfm);
1722 drbg->priv_data = NULL;
1723
1724 if (drbg->ctr_handle)
1725 crypto_free_skcipher(drbg->ctr_handle);
1726 drbg->ctr_handle = NULL;
1727
1728 if (drbg->ctr_req)
1729 skcipher_request_free(drbg->ctr_req);
1730 drbg->ctr_req = NULL;
1731
1732 kfree(drbg->outscratchpadbuf);
1733 drbg->outscratchpadbuf = NULL;
1734
1735 return 0;
1736 }
1737
drbg_init_sym_kernel(struct drbg_state * drbg)1738 static int drbg_init_sym_kernel(struct drbg_state *drbg)
1739 {
1740 struct crypto_cipher *tfm;
1741 struct crypto_skcipher *sk_tfm;
1742 struct skcipher_request *req;
1743 unsigned int alignmask;
1744 char ctr_name[CRYPTO_MAX_ALG_NAME];
1745
1746 tfm = crypto_alloc_cipher(drbg->core->backend_cra_name, 0, 0);
1747 if (IS_ERR(tfm)) {
1748 pr_info("DRBG: could not allocate cipher TFM handle: %s\n",
1749 drbg->core->backend_cra_name);
1750 return PTR_ERR(tfm);
1751 }
1752 BUG_ON(drbg_blocklen(drbg) != crypto_cipher_blocksize(tfm));
1753 drbg->priv_data = tfm;
1754
1755 if (snprintf(ctr_name, CRYPTO_MAX_ALG_NAME, "ctr(%s)",
1756 drbg->core->backend_cra_name) >= CRYPTO_MAX_ALG_NAME) {
1757 drbg_fini_sym_kernel(drbg);
1758 return -EINVAL;
1759 }
1760 sk_tfm = crypto_alloc_skcipher(ctr_name, 0, 0);
1761 if (IS_ERR(sk_tfm)) {
1762 pr_info("DRBG: could not allocate CTR cipher TFM handle: %s\n",
1763 ctr_name);
1764 drbg_fini_sym_kernel(drbg);
1765 return PTR_ERR(sk_tfm);
1766 }
1767 drbg->ctr_handle = sk_tfm;
1768 crypto_init_wait(&drbg->ctr_wait);
1769
1770 req = skcipher_request_alloc(sk_tfm, GFP_KERNEL);
1771 if (!req) {
1772 pr_info("DRBG: could not allocate request queue\n");
1773 drbg_fini_sym_kernel(drbg);
1774 return -ENOMEM;
1775 }
1776 drbg->ctr_req = req;
1777 skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
1778 CRYPTO_TFM_REQ_MAY_SLEEP,
1779 crypto_req_done, &drbg->ctr_wait);
1780
1781 alignmask = crypto_skcipher_alignmask(sk_tfm);
1782 drbg->outscratchpadbuf = kmalloc(DRBG_OUTSCRATCHLEN + alignmask,
1783 GFP_KERNEL);
1784 if (!drbg->outscratchpadbuf) {
1785 drbg_fini_sym_kernel(drbg);
1786 return -ENOMEM;
1787 }
1788 drbg->outscratchpad = (u8 *)PTR_ALIGN(drbg->outscratchpadbuf,
1789 alignmask + 1);
1790
1791 sg_init_table(&drbg->sg_in, 1);
1792 sg_init_one(&drbg->sg_out, drbg->outscratchpad, DRBG_OUTSCRATCHLEN);
1793
1794 return alignmask;
1795 }
1796
drbg_kcapi_symsetkey(struct drbg_state * drbg,const unsigned char * key)1797 static void drbg_kcapi_symsetkey(struct drbg_state *drbg,
1798 const unsigned char *key)
1799 {
1800 struct crypto_cipher *tfm =
1801 (struct crypto_cipher *)drbg->priv_data;
1802
1803 crypto_cipher_setkey(tfm, key, (drbg_keylen(drbg)));
1804 }
1805
drbg_kcapi_sym(struct drbg_state * drbg,unsigned char * outval,const struct drbg_string * in)1806 static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
1807 const struct drbg_string *in)
1808 {
1809 struct crypto_cipher *tfm =
1810 (struct crypto_cipher *)drbg->priv_data;
1811
1812 /* there is only component in *in */
1813 BUG_ON(in->len < drbg_blocklen(drbg));
1814 crypto_cipher_encrypt_one(tfm, outval, in->buf);
1815 return 0;
1816 }
1817
drbg_kcapi_sym_ctr(struct drbg_state * drbg,u8 * inbuf,u32 inlen,u8 * outbuf,u32 outlen)1818 static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
1819 u8 *inbuf, u32 inlen,
1820 u8 *outbuf, u32 outlen)
1821 {
1822 struct scatterlist *sg_in = &drbg->sg_in, *sg_out = &drbg->sg_out;
1823 u32 scratchpad_use = min_t(u32, outlen, DRBG_OUTSCRATCHLEN);
1824 int ret;
1825
1826 if (inbuf) {
1827 /* Use caller-provided input buffer */
1828 sg_set_buf(sg_in, inbuf, inlen);
1829 } else {
1830 /* Use scratchpad for in-place operation */
1831 inlen = scratchpad_use;
1832 memset(drbg->outscratchpad, 0, scratchpad_use);
1833 sg_set_buf(sg_in, drbg->outscratchpad, scratchpad_use);
1834 }
1835
1836 while (outlen) {
1837 u32 cryptlen = min3(inlen, outlen, (u32)DRBG_OUTSCRATCHLEN);
1838
1839 /* Output buffer may not be valid for SGL, use scratchpad */
1840 skcipher_request_set_crypt(drbg->ctr_req, sg_in, sg_out,
1841 cryptlen, drbg->V);
1842 ret = crypto_wait_req(crypto_skcipher_encrypt(drbg->ctr_req),
1843 &drbg->ctr_wait);
1844 if (ret)
1845 goto out;
1846
1847 crypto_init_wait(&drbg->ctr_wait);
1848
1849 memcpy(outbuf, drbg->outscratchpad, cryptlen);
1850 memzero_explicit(drbg->outscratchpad, cryptlen);
1851
1852 outlen -= cryptlen;
1853 outbuf += cryptlen;
1854 }
1855 ret = 0;
1856
1857 out:
1858 return ret;
1859 }
1860 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1861
1862 /***************************************************************
1863 * Kernel crypto API interface to register DRBG
1864 ***************************************************************/
1865
1866 /*
1867 * Look up the DRBG flags by given kernel crypto API cra_name
1868 * The code uses the drbg_cores definition to do this
1869 *
1870 * @cra_name kernel crypto API cra_name
1871 * @coreref reference to integer which is filled with the pointer to
1872 * the applicable core
1873 * @pr reference for setting prediction resistance
1874 *
1875 * return: flags
1876 */
drbg_convert_tfm_core(const char * cra_driver_name,int * coreref,bool * pr)1877 static inline void drbg_convert_tfm_core(const char *cra_driver_name,
1878 int *coreref, bool *pr)
1879 {
1880 int i = 0;
1881 size_t start = 0;
1882 int len = 0;
1883
1884 *pr = true;
1885 /* disassemble the names */
1886 if (!memcmp(cra_driver_name, "drbg_nopr_", 10)) {
1887 start = 10;
1888 *pr = false;
1889 } else if (!memcmp(cra_driver_name, "drbg_pr_", 8)) {
1890 start = 8;
1891 } else {
1892 return;
1893 }
1894
1895 /* remove the first part */
1896 len = strlen(cra_driver_name) - start;
1897 for (i = 0; ARRAY_SIZE(drbg_cores) > i; i++) {
1898 if (!memcmp(cra_driver_name + start, drbg_cores[i].cra_name,
1899 len)) {
1900 *coreref = i;
1901 return;
1902 }
1903 }
1904 }
1905
drbg_kcapi_init(struct crypto_tfm * tfm)1906 static int drbg_kcapi_init(struct crypto_tfm *tfm)
1907 {
1908 struct drbg_state *drbg = crypto_tfm_ctx(tfm);
1909
1910 mutex_init(&drbg->drbg_mutex);
1911
1912 return 0;
1913 }
1914
drbg_kcapi_cleanup(struct crypto_tfm * tfm)1915 static void drbg_kcapi_cleanup(struct crypto_tfm *tfm)
1916 {
1917 drbg_uninstantiate(crypto_tfm_ctx(tfm));
1918 }
1919
1920 /*
1921 * Generate random numbers invoked by the kernel crypto API:
1922 * The API of the kernel crypto API is extended as follows:
1923 *
1924 * src is additional input supplied to the RNG.
1925 * slen is the length of src.
1926 * dst is the output buffer where random data is to be stored.
1927 * dlen is the length of dst.
1928 */
drbg_kcapi_random(struct crypto_rng * tfm,const u8 * src,unsigned int slen,u8 * dst,unsigned int dlen)1929 static int drbg_kcapi_random(struct crypto_rng *tfm,
1930 const u8 *src, unsigned int slen,
1931 u8 *dst, unsigned int dlen)
1932 {
1933 struct drbg_state *drbg = crypto_rng_ctx(tfm);
1934 struct drbg_string *addtl = NULL;
1935 struct drbg_string string;
1936
1937 if (slen) {
1938 /* linked list variable is now local to allow modification */
1939 drbg_string_fill(&string, src, slen);
1940 addtl = &string;
1941 }
1942
1943 return drbg_generate_long(drbg, dst, dlen, addtl);
1944 }
1945
1946 /*
1947 * Seed the DRBG invoked by the kernel crypto API
1948 */
drbg_kcapi_seed(struct crypto_rng * tfm,const u8 * seed,unsigned int slen)1949 static int drbg_kcapi_seed(struct crypto_rng *tfm,
1950 const u8 *seed, unsigned int slen)
1951 {
1952 struct drbg_state *drbg = crypto_rng_ctx(tfm);
1953 struct crypto_tfm *tfm_base = crypto_rng_tfm(tfm);
1954 bool pr = false;
1955 struct drbg_string string;
1956 struct drbg_string *seed_string = NULL;
1957 int coreref = 0;
1958
1959 drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base), &coreref,
1960 &pr);
1961 if (0 < slen) {
1962 drbg_string_fill(&string, seed, slen);
1963 seed_string = &string;
1964 }
1965
1966 return drbg_instantiate(drbg, seed_string, coreref, pr);
1967 }
1968
1969 /***************************************************************
1970 * Kernel module: code to load the module
1971 ***************************************************************/
1972
1973 /*
1974 * Tests as defined in 11.3.2 in addition to the cipher tests: testing
1975 * of the error handling.
1976 *
1977 * Note: testing of failing seed source as defined in 11.3.2 is not applicable
1978 * as seed source of get_random_bytes does not fail.
1979 *
1980 * Note 2: There is no sensible way of testing the reseed counter
1981 * enforcement, so skip it.
1982 */
drbg_healthcheck_sanity(void)1983 static inline int __init drbg_healthcheck_sanity(void)
1984 {
1985 int len = 0;
1986 #define OUTBUFLEN 16
1987 unsigned char buf[OUTBUFLEN];
1988 struct drbg_state *drbg = NULL;
1989 int ret = -EFAULT;
1990 int rc = -EFAULT;
1991 bool pr = false;
1992 int coreref = 0;
1993 struct drbg_string addtl;
1994 size_t max_addtllen, max_request_bytes;
1995
1996 /* only perform test in FIPS mode */
1997 if (!fips_enabled)
1998 return 0;
1999
2000 #ifdef CONFIG_CRYPTO_DRBG_CTR
2001 drbg_convert_tfm_core("drbg_nopr_ctr_aes128", &coreref, &pr);
2002 #elif defined CONFIG_CRYPTO_DRBG_HASH
2003 drbg_convert_tfm_core("drbg_nopr_sha256", &coreref, &pr);
2004 #else
2005 drbg_convert_tfm_core("drbg_nopr_hmac_sha256", &coreref, &pr);
2006 #endif
2007
2008 drbg = kzalloc(sizeof(struct drbg_state), GFP_KERNEL);
2009 if (!drbg)
2010 return -ENOMEM;
2011
2012 mutex_init(&drbg->drbg_mutex);
2013 drbg->core = &drbg_cores[coreref];
2014 drbg->reseed_threshold = drbg_max_requests(drbg);
2015
2016 /*
2017 * if the following tests fail, it is likely that there is a buffer
2018 * overflow as buf is much smaller than the requested or provided
2019 * string lengths -- in case the error handling does not succeed
2020 * we may get an OOPS. And we want to get an OOPS as this is a
2021 * grave bug.
2022 */
2023
2024 max_addtllen = drbg_max_addtl(drbg);
2025 max_request_bytes = drbg_max_request_bytes(drbg);
2026 drbg_string_fill(&addtl, buf, max_addtllen + 1);
2027 /* overflow addtllen with additonal info string */
2028 len = drbg_generate(drbg, buf, OUTBUFLEN, &addtl);
2029 BUG_ON(0 < len);
2030 /* overflow max_bits */
2031 len = drbg_generate(drbg, buf, (max_request_bytes + 1), NULL);
2032 BUG_ON(0 < len);
2033
2034 /* overflow max addtllen with personalization string */
2035 ret = drbg_seed(drbg, &addtl, false);
2036 BUG_ON(0 == ret);
2037 /* all tests passed */
2038 rc = 0;
2039
2040 pr_devel("DRBG: Sanity tests for failure code paths successfully "
2041 "completed\n");
2042
2043 kfree(drbg);
2044 return rc;
2045 }
2046
2047 static struct rng_alg drbg_algs[22];
2048
2049 /*
2050 * Fill the array drbg_algs used to register the different DRBGs
2051 * with the kernel crypto API. To fill the array, the information
2052 * from drbg_cores[] is used.
2053 */
drbg_fill_array(struct rng_alg * alg,const struct drbg_core * core,int pr)2054 static inline void __init drbg_fill_array(struct rng_alg *alg,
2055 const struct drbg_core *core, int pr)
2056 {
2057 int pos = 0;
2058 static int priority = 200;
2059
2060 memcpy(alg->base.cra_name, "stdrng", 6);
2061 if (pr) {
2062 memcpy(alg->base.cra_driver_name, "drbg_pr_", 8);
2063 pos = 8;
2064 } else {
2065 memcpy(alg->base.cra_driver_name, "drbg_nopr_", 10);
2066 pos = 10;
2067 }
2068 memcpy(alg->base.cra_driver_name + pos, core->cra_name,
2069 strlen(core->cra_name));
2070
2071 alg->base.cra_priority = priority;
2072 priority++;
2073 /*
2074 * If FIPS mode enabled, the selected DRBG shall have the
2075 * highest cra_priority over other stdrng instances to ensure
2076 * it is selected.
2077 */
2078 if (fips_enabled)
2079 alg->base.cra_priority += 200;
2080
2081 alg->base.cra_ctxsize = sizeof(struct drbg_state);
2082 alg->base.cra_module = THIS_MODULE;
2083 alg->base.cra_init = drbg_kcapi_init;
2084 alg->base.cra_exit = drbg_kcapi_cleanup;
2085 alg->generate = drbg_kcapi_random;
2086 alg->seed = drbg_kcapi_seed;
2087 alg->set_ent = drbg_kcapi_set_entropy;
2088 alg->seedsize = 0;
2089 }
2090
drbg_init(void)2091 static int __init drbg_init(void)
2092 {
2093 unsigned int i = 0; /* pointer to drbg_algs */
2094 unsigned int j = 0; /* pointer to drbg_cores */
2095 int ret;
2096
2097 ret = drbg_healthcheck_sanity();
2098 if (ret)
2099 return ret;
2100
2101 if (ARRAY_SIZE(drbg_cores) * 2 > ARRAY_SIZE(drbg_algs)) {
2102 pr_info("DRBG: Cannot register all DRBG types"
2103 "(slots needed: %zu, slots available: %zu)\n",
2104 ARRAY_SIZE(drbg_cores) * 2, ARRAY_SIZE(drbg_algs));
2105 return -EFAULT;
2106 }
2107
2108 /*
2109 * each DRBG definition can be used with PR and without PR, thus
2110 * we instantiate each DRBG in drbg_cores[] twice.
2111 *
2112 * As the order of placing them into the drbg_algs array matters
2113 * (the later DRBGs receive a higher cra_priority) we register the
2114 * prediction resistance DRBGs first as the should not be too
2115 * interesting.
2116 */
2117 for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
2118 drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 1);
2119 for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
2120 drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 0);
2121 return crypto_register_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
2122 }
2123
drbg_exit(void)2124 static void __exit drbg_exit(void)
2125 {
2126 crypto_unregister_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
2127 }
2128
2129 subsys_initcall(drbg_init);
2130 module_exit(drbg_exit);
2131 #ifndef CRYPTO_DRBG_HASH_STRING
2132 #define CRYPTO_DRBG_HASH_STRING ""
2133 #endif
2134 #ifndef CRYPTO_DRBG_HMAC_STRING
2135 #define CRYPTO_DRBG_HMAC_STRING ""
2136 #endif
2137 #ifndef CRYPTO_DRBG_CTR_STRING
2138 #define CRYPTO_DRBG_CTR_STRING ""
2139 #endif
2140 MODULE_LICENSE("GPL");
2141 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
2142 MODULE_DESCRIPTION("NIST SP800-90A Deterministic Random Bit Generator (DRBG) "
2143 "using following cores: "
2144 CRYPTO_DRBG_HASH_STRING
2145 CRYPTO_DRBG_HMAC_STRING
2146 CRYPTO_DRBG_CTR_STRING);
2147 MODULE_ALIAS_CRYPTO("stdrng");
2148
