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 <crypto/internal/cipher.h>
102 #include <linux/kernel.h>
103 #include <linux/jiffies.h>
104
105 /***************************************************************
106 * Backend cipher definitions available to DRBG
107 ***************************************************************/
108
109 /*
110 * The order of the DRBG definitions here matter: every DRBG is registered
111 * as stdrng. Each DRBG receives an increasing cra_priority values the later
112 * they are defined in this array (see drbg_fill_array).
113 *
114 * HMAC DRBGs are favored over Hash DRBGs over CTR DRBGs, and
115 * the SHA256 / AES 256 over other ciphers. Thus, the favored
116 * DRBGs are the latest entries in this array.
117 */
118 static const struct drbg_core drbg_cores[] = {
119 #ifdef CONFIG_CRYPTO_DRBG_CTR
120 {
121 .flags = DRBG_CTR | DRBG_STRENGTH128,
122 .statelen = 32, /* 256 bits as defined in 10.2.1 */
123 .blocklen_bytes = 16,
124 .cra_name = "ctr_aes128",
125 .backend_cra_name = "aes",
126 }, {
127 .flags = DRBG_CTR | DRBG_STRENGTH192,
128 .statelen = 40, /* 320 bits as defined in 10.2.1 */
129 .blocklen_bytes = 16,
130 .cra_name = "ctr_aes192",
131 .backend_cra_name = "aes",
132 }, {
133 .flags = DRBG_CTR | DRBG_STRENGTH256,
134 .statelen = 48, /* 384 bits as defined in 10.2.1 */
135 .blocklen_bytes = 16,
136 .cra_name = "ctr_aes256",
137 .backend_cra_name = "aes",
138 },
139 #endif /* CONFIG_CRYPTO_DRBG_CTR */
140 #ifdef CONFIG_CRYPTO_DRBG_HASH
141 {
142 .flags = DRBG_HASH | DRBG_STRENGTH128,
143 .statelen = 55, /* 440 bits */
144 .blocklen_bytes = 20,
145 .cra_name = "sha1",
146 .backend_cra_name = "sha1",
147 }, {
148 .flags = DRBG_HASH | DRBG_STRENGTH256,
149 .statelen = 111, /* 888 bits */
150 .blocklen_bytes = 48,
151 .cra_name = "sha384",
152 .backend_cra_name = "sha384",
153 }, {
154 .flags = DRBG_HASH | DRBG_STRENGTH256,
155 .statelen = 111, /* 888 bits */
156 .blocklen_bytes = 64,
157 .cra_name = "sha512",
158 .backend_cra_name = "sha512",
159 }, {
160 .flags = DRBG_HASH | DRBG_STRENGTH256,
161 .statelen = 55, /* 440 bits */
162 .blocklen_bytes = 32,
163 .cra_name = "sha256",
164 .backend_cra_name = "sha256",
165 },
166 #endif /* CONFIG_CRYPTO_DRBG_HASH */
167 #ifdef CONFIG_CRYPTO_DRBG_HMAC
168 {
169 .flags = DRBG_HMAC | DRBG_STRENGTH128,
170 .statelen = 20, /* block length of cipher */
171 .blocklen_bytes = 20,
172 .cra_name = "hmac_sha1",
173 .backend_cra_name = "hmac(sha1)",
174 }, {
175 .flags = DRBG_HMAC | DRBG_STRENGTH256,
176 .statelen = 48, /* block length of cipher */
177 .blocklen_bytes = 48,
178 .cra_name = "hmac_sha384",
179 .backend_cra_name = "hmac(sha384)",
180 }, {
181 .flags = DRBG_HMAC | DRBG_STRENGTH256,
182 .statelen = 32, /* block length of cipher */
183 .blocklen_bytes = 32,
184 .cra_name = "hmac_sha256",
185 .backend_cra_name = "hmac(sha256)",
186 }, {
187 .flags = DRBG_HMAC | DRBG_STRENGTH256,
188 .statelen = 64, /* block length of cipher */
189 .blocklen_bytes = 64,
190 .cra_name = "hmac_sha512",
191 .backend_cra_name = "hmac(sha512)",
192 },
193 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
194 };
195
196 static int drbg_uninstantiate(struct drbg_state *drbg);
197
198 /******************************************************************
199 * Generic helper functions
200 ******************************************************************/
201
202 /*
203 * Return strength of DRBG according to SP800-90A section 8.4
204 *
205 * @flags DRBG flags reference
206 *
207 * Return: normalized strength in *bytes* value or 32 as default
208 * to counter programming errors
209 */
drbg_sec_strength(drbg_flag_t flags)210 static inline unsigned short drbg_sec_strength(drbg_flag_t flags)
211 {
212 switch (flags & DRBG_STRENGTH_MASK) {
213 case DRBG_STRENGTH128:
214 return 16;
215 case DRBG_STRENGTH192:
216 return 24;
217 case DRBG_STRENGTH256:
218 return 32;
219 default:
220 return 32;
221 }
222 }
223
224 /*
225 * FIPS 140-2 continuous self test for the noise source
226 * The test is performed on the noise source input data. Thus, the function
227 * implicitly knows the size of the buffer to be equal to the security
228 * strength.
229 *
230 * Note, this function disregards the nonce trailing the entropy data during
231 * initial seeding.
232 *
233 * drbg->drbg_mutex must have been taken.
234 *
235 * @drbg DRBG handle
236 * @entropy buffer of seed data to be checked
237 *
238 * return:
239 * 0 on success
240 * -EAGAIN on when the CTRNG is not yet primed
241 * < 0 on error
242 */
drbg_fips_continuous_test(struct drbg_state * drbg,const unsigned char * entropy)243 static int drbg_fips_continuous_test(struct drbg_state *drbg,
244 const unsigned char *entropy)
245 {
246 unsigned short entropylen = drbg_sec_strength(drbg->core->flags);
247 int ret = 0;
248
249 if (!IS_ENABLED(CONFIG_CRYPTO_FIPS))
250 return 0;
251
252 /* skip test if we test the overall system */
253 if (list_empty(&drbg->test_data.list))
254 return 0;
255 /* only perform test in FIPS mode */
256 if (!fips_enabled)
257 return 0;
258
259 if (!drbg->fips_primed) {
260 /* Priming of FIPS test */
261 memcpy(drbg->prev, entropy, entropylen);
262 drbg->fips_primed = true;
263 /* priming: another round is needed */
264 return -EAGAIN;
265 }
266 ret = memcmp(drbg->prev, entropy, entropylen);
267 if (!ret)
268 panic("DRBG continuous self test failed\n");
269 memcpy(drbg->prev, entropy, entropylen);
270
271 /* the test shall pass when the two values are not equal */
272 return 0;
273 }
274
275 /*
276 * Convert an integer into a byte representation of this integer.
277 * The byte representation is big-endian
278 *
279 * @val value to be converted
280 * @buf buffer holding the converted integer -- caller must ensure that
281 * buffer size is at least 32 bit
282 */
283 #if (defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR))
drbg_cpu_to_be32(__u32 val,unsigned char * buf)284 static inline void drbg_cpu_to_be32(__u32 val, unsigned char *buf)
285 {
286 struct s {
287 __be32 conv;
288 };
289 struct s *conversion = (struct s *) buf;
290
291 conversion->conv = cpu_to_be32(val);
292 }
293 #endif /* defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR) */
294
295 /******************************************************************
296 * CTR DRBG callback functions
297 ******************************************************************/
298
299 #ifdef CONFIG_CRYPTO_DRBG_CTR
300 #define CRYPTO_DRBG_CTR_STRING "CTR "
301 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes256");
302 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes256");
303 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes192");
304 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes192");
305 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes128");
306 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes128");
307
308 static void drbg_kcapi_symsetkey(struct drbg_state *drbg,
309 const unsigned char *key);
310 static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
311 const struct drbg_string *in);
312 static int drbg_init_sym_kernel(struct drbg_state *drbg);
313 static int drbg_fini_sym_kernel(struct drbg_state *drbg);
314 static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
315 u8 *inbuf, u32 inbuflen,
316 u8 *outbuf, u32 outlen);
317 #define DRBG_OUTSCRATCHLEN 256
318
319 /* 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)320 static int drbg_ctr_bcc(struct drbg_state *drbg,
321 unsigned char *out, const unsigned char *key,
322 struct list_head *in)
323 {
324 int ret = 0;
325 struct drbg_string *curr = NULL;
326 struct drbg_string data;
327 short cnt = 0;
328
329 drbg_string_fill(&data, out, drbg_blocklen(drbg));
330
331 /* 10.4.3 step 2 / 4 */
332 drbg_kcapi_symsetkey(drbg, key);
333 list_for_each_entry(curr, in, list) {
334 const unsigned char *pos = curr->buf;
335 size_t len = curr->len;
336 /* 10.4.3 step 4.1 */
337 while (len) {
338 /* 10.4.3 step 4.2 */
339 if (drbg_blocklen(drbg) == cnt) {
340 cnt = 0;
341 ret = drbg_kcapi_sym(drbg, out, &data);
342 if (ret)
343 return ret;
344 }
345 out[cnt] ^= *pos;
346 pos++;
347 cnt++;
348 len--;
349 }
350 }
351 /* 10.4.3 step 4.2 for last block */
352 if (cnt)
353 ret = drbg_kcapi_sym(drbg, out, &data);
354
355 return ret;
356 }
357
358 /*
359 * scratchpad usage: drbg_ctr_update is interlinked with drbg_ctr_df
360 * (and drbg_ctr_bcc, but this function does not need any temporary buffers),
361 * the scratchpad is used as follows:
362 * drbg_ctr_update:
363 * temp
364 * start: drbg->scratchpad
365 * length: drbg_statelen(drbg) + drbg_blocklen(drbg)
366 * note: the cipher writing into this variable works
367 * blocklen-wise. Now, when the statelen is not a multiple
368 * of blocklen, the generateion loop below "spills over"
369 * by at most blocklen. Thus, we need to give sufficient
370 * memory.
371 * df_data
372 * start: drbg->scratchpad +
373 * drbg_statelen(drbg) + drbg_blocklen(drbg)
374 * length: drbg_statelen(drbg)
375 *
376 * drbg_ctr_df:
377 * pad
378 * start: df_data + drbg_statelen(drbg)
379 * length: drbg_blocklen(drbg)
380 * iv
381 * start: pad + drbg_blocklen(drbg)
382 * length: drbg_blocklen(drbg)
383 * temp
384 * start: iv + drbg_blocklen(drbg)
385 * length: drbg_satelen(drbg) + drbg_blocklen(drbg)
386 * note: temp is the buffer that the BCC function operates
387 * on. BCC operates blockwise. drbg_statelen(drbg)
388 * is sufficient when the DRBG state length is a multiple
389 * of the block size. For AES192 (and maybe other ciphers)
390 * this is not correct and the length for temp is
391 * insufficient (yes, that also means for such ciphers,
392 * the final output of all BCC rounds are truncated).
393 * Therefore, add drbg_blocklen(drbg) to cover all
394 * possibilities.
395 */
396
397 /* 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)398 static int drbg_ctr_df(struct drbg_state *drbg,
399 unsigned char *df_data, size_t bytes_to_return,
400 struct list_head *seedlist)
401 {
402 int ret = -EFAULT;
403 unsigned char L_N[8];
404 /* S3 is input */
405 struct drbg_string S1, S2, S4, cipherin;
406 LIST_HEAD(bcc_list);
407 unsigned char *pad = df_data + drbg_statelen(drbg);
408 unsigned char *iv = pad + drbg_blocklen(drbg);
409 unsigned char *temp = iv + drbg_blocklen(drbg);
410 size_t padlen = 0;
411 unsigned int templen = 0;
412 /* 10.4.2 step 7 */
413 unsigned int i = 0;
414 /* 10.4.2 step 8 */
415 const unsigned char *K = (unsigned char *)
416 "\x00\x01\x02\x03\x04\x05\x06\x07"
417 "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
418 "\x10\x11\x12\x13\x14\x15\x16\x17"
419 "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f";
420 unsigned char *X;
421 size_t generated_len = 0;
422 size_t inputlen = 0;
423 struct drbg_string *seed = NULL;
424
425 memset(pad, 0, drbg_blocklen(drbg));
426 memset(iv, 0, drbg_blocklen(drbg));
427
428 /* 10.4.2 step 1 is implicit as we work byte-wise */
429
430 /* 10.4.2 step 2 */
431 if ((512/8) < bytes_to_return)
432 return -EINVAL;
433
434 /* 10.4.2 step 2 -- calculate the entire length of all input data */
435 list_for_each_entry(seed, seedlist, list)
436 inputlen += seed->len;
437 drbg_cpu_to_be32(inputlen, &L_N[0]);
438
439 /* 10.4.2 step 3 */
440 drbg_cpu_to_be32(bytes_to_return, &L_N[4]);
441
442 /* 10.4.2 step 5: length is L_N, input_string, one byte, padding */
443 padlen = (inputlen + sizeof(L_N) + 1) % (drbg_blocklen(drbg));
444 /* wrap the padlen appropriately */
445 if (padlen)
446 padlen = drbg_blocklen(drbg) - padlen;
447 /*
448 * pad / padlen contains the 0x80 byte and the following zero bytes.
449 * As the calculated padlen value only covers the number of zero
450 * bytes, this value has to be incremented by one for the 0x80 byte.
451 */
452 padlen++;
453 pad[0] = 0x80;
454
455 /* 10.4.2 step 4 -- first fill the linked list and then order it */
456 drbg_string_fill(&S1, iv, drbg_blocklen(drbg));
457 list_add_tail(&S1.list, &bcc_list);
458 drbg_string_fill(&S2, L_N, sizeof(L_N));
459 list_add_tail(&S2.list, &bcc_list);
460 list_splice_tail(seedlist, &bcc_list);
461 drbg_string_fill(&S4, pad, padlen);
462 list_add_tail(&S4.list, &bcc_list);
463
464 /* 10.4.2 step 9 */
465 while (templen < (drbg_keylen(drbg) + (drbg_blocklen(drbg)))) {
466 /*
467 * 10.4.2 step 9.1 - the padding is implicit as the buffer
468 * holds zeros after allocation -- even the increment of i
469 * is irrelevant as the increment remains within length of i
470 */
471 drbg_cpu_to_be32(i, iv);
472 /* 10.4.2 step 9.2 -- BCC and concatenation with temp */
473 ret = drbg_ctr_bcc(drbg, temp + templen, K, &bcc_list);
474 if (ret)
475 goto out;
476 /* 10.4.2 step 9.3 */
477 i++;
478 templen += drbg_blocklen(drbg);
479 }
480
481 /* 10.4.2 step 11 */
482 X = temp + (drbg_keylen(drbg));
483 drbg_string_fill(&cipherin, X, drbg_blocklen(drbg));
484
485 /* 10.4.2 step 12: overwriting of outval is implemented in next step */
486
487 /* 10.4.2 step 13 */
488 drbg_kcapi_symsetkey(drbg, temp);
489 while (generated_len < bytes_to_return) {
490 short blocklen = 0;
491 /*
492 * 10.4.2 step 13.1: the truncation of the key length is
493 * implicit as the key is only drbg_blocklen in size based on
494 * the implementation of the cipher function callback
495 */
496 ret = drbg_kcapi_sym(drbg, X, &cipherin);
497 if (ret)
498 goto out;
499 blocklen = (drbg_blocklen(drbg) <
500 (bytes_to_return - generated_len)) ?
501 drbg_blocklen(drbg) :
502 (bytes_to_return - generated_len);
503 /* 10.4.2 step 13.2 and 14 */
504 memcpy(df_data + generated_len, X, blocklen);
505 generated_len += blocklen;
506 }
507
508 ret = 0;
509
510 out:
511 memset(iv, 0, drbg_blocklen(drbg));
512 memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
513 memset(pad, 0, drbg_blocklen(drbg));
514 return ret;
515 }
516
517 /*
518 * update function of CTR DRBG as defined in 10.2.1.2
519 *
520 * The reseed variable has an enhanced meaning compared to the update
521 * functions of the other DRBGs as follows:
522 * 0 => initial seed from initialization
523 * 1 => reseed via drbg_seed
524 * 2 => first invocation from drbg_ctr_update when addtl is present. In
525 * this case, the df_data scratchpad is not deleted so that it is
526 * available for another calls to prevent calling the DF function
527 * again.
528 * 3 => second invocation from drbg_ctr_update. When the update function
529 * was called with addtl, the df_data memory already contains the
530 * DFed addtl information and we do not need to call DF again.
531 */
drbg_ctr_update(struct drbg_state * drbg,struct list_head * seed,int reseed)532 static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed,
533 int reseed)
534 {
535 int ret = -EFAULT;
536 /* 10.2.1.2 step 1 */
537 unsigned char *temp = drbg->scratchpad;
538 unsigned char *df_data = drbg->scratchpad + drbg_statelen(drbg) +
539 drbg_blocklen(drbg);
540
541 if (3 > reseed)
542 memset(df_data, 0, drbg_statelen(drbg));
543
544 if (!reseed) {
545 /*
546 * The DRBG uses the CTR mode of the underlying AES cipher. The
547 * CTR mode increments the counter value after the AES operation
548 * but SP800-90A requires that the counter is incremented before
549 * the AES operation. Hence, we increment it at the time we set
550 * it by one.
551 */
552 crypto_inc(drbg->V, drbg_blocklen(drbg));
553
554 ret = crypto_skcipher_setkey(drbg->ctr_handle, drbg->C,
555 drbg_keylen(drbg));
556 if (ret)
557 goto out;
558 }
559
560 /* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */
561 if (seed) {
562 ret = drbg_ctr_df(drbg, df_data, drbg_statelen(drbg), seed);
563 if (ret)
564 goto out;
565 }
566
567 ret = drbg_kcapi_sym_ctr(drbg, df_data, drbg_statelen(drbg),
568 temp, drbg_statelen(drbg));
569 if (ret)
570 return ret;
571
572 /* 10.2.1.2 step 5 */
573 ret = crypto_skcipher_setkey(drbg->ctr_handle, temp,
574 drbg_keylen(drbg));
575 if (ret)
576 goto out;
577 /* 10.2.1.2 step 6 */
578 memcpy(drbg->V, temp + drbg_keylen(drbg), drbg_blocklen(drbg));
579 /* See above: increment counter by one to compensate timing of CTR op */
580 crypto_inc(drbg->V, drbg_blocklen(drbg));
581 ret = 0;
582
583 out:
584 memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
585 if (2 != reseed)
586 memset(df_data, 0, drbg_statelen(drbg));
587 return ret;
588 }
589
590 /*
591 * scratchpad use: drbg_ctr_update is called independently from
592 * drbg_ctr_extract_bytes. Therefore, the scratchpad is reused
593 */
594 /* 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)595 static int drbg_ctr_generate(struct drbg_state *drbg,
596 unsigned char *buf, unsigned int buflen,
597 struct list_head *addtl)
598 {
599 int ret;
600 int len = min_t(int, buflen, INT_MAX);
601
602 /* 10.2.1.5.2 step 2 */
603 if (addtl && !list_empty(addtl)) {
604 ret = drbg_ctr_update(drbg, addtl, 2);
605 if (ret)
606 return 0;
607 }
608
609 /* 10.2.1.5.2 step 4.1 */
610 ret = drbg_kcapi_sym_ctr(drbg, NULL, 0, buf, len);
611 if (ret)
612 return ret;
613
614 /* 10.2.1.5.2 step 6 */
615 ret = drbg_ctr_update(drbg, NULL, 3);
616 if (ret)
617 len = ret;
618
619 return len;
620 }
621
622 static const struct drbg_state_ops drbg_ctr_ops = {
623 .update = drbg_ctr_update,
624 .generate = drbg_ctr_generate,
625 .crypto_init = drbg_init_sym_kernel,
626 .crypto_fini = drbg_fini_sym_kernel,
627 };
628 #endif /* CONFIG_CRYPTO_DRBG_CTR */
629
630 /******************************************************************
631 * HMAC DRBG callback functions
632 ******************************************************************/
633
634 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
635 static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
636 const struct list_head *in);
637 static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
638 const unsigned char *key);
639 static int drbg_init_hash_kernel(struct drbg_state *drbg);
640 static int drbg_fini_hash_kernel(struct drbg_state *drbg);
641 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
642
643 #ifdef CONFIG_CRYPTO_DRBG_HMAC
644 #define CRYPTO_DRBG_HMAC_STRING "HMAC "
645 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha512");
646 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha512");
647 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha384");
648 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha384");
649 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha256");
650 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha256");
651 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha1");
652 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha1");
653
654 /* 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)655 static int drbg_hmac_update(struct drbg_state *drbg, struct list_head *seed,
656 int reseed)
657 {
658 int ret = -EFAULT;
659 int i = 0;
660 struct drbg_string seed1, seed2, vdata;
661 LIST_HEAD(seedlist);
662 LIST_HEAD(vdatalist);
663
664 if (!reseed) {
665 /* 10.1.2.3 step 2 -- memset(0) of C is implicit with kzalloc */
666 memset(drbg->V, 1, drbg_statelen(drbg));
667 drbg_kcapi_hmacsetkey(drbg, drbg->C);
668 }
669
670 drbg_string_fill(&seed1, drbg->V, drbg_statelen(drbg));
671 list_add_tail(&seed1.list, &seedlist);
672 /* buffer of seed2 will be filled in for loop below with one byte */
673 drbg_string_fill(&seed2, NULL, 1);
674 list_add_tail(&seed2.list, &seedlist);
675 /* input data of seed is allowed to be NULL at this point */
676 if (seed)
677 list_splice_tail(seed, &seedlist);
678
679 drbg_string_fill(&vdata, drbg->V, drbg_statelen(drbg));
680 list_add_tail(&vdata.list, &vdatalist);
681 for (i = 2; 0 < i; i--) {
682 /* first round uses 0x0, second 0x1 */
683 unsigned char prefix = DRBG_PREFIX0;
684 if (1 == i)
685 prefix = DRBG_PREFIX1;
686 /* 10.1.2.2 step 1 and 4 -- concatenation and HMAC for key */
687 seed2.buf = &prefix;
688 ret = drbg_kcapi_hash(drbg, drbg->C, &seedlist);
689 if (ret)
690 return ret;
691 drbg_kcapi_hmacsetkey(drbg, drbg->C);
692
693 /* 10.1.2.2 step 2 and 5 -- HMAC for V */
694 ret = drbg_kcapi_hash(drbg, drbg->V, &vdatalist);
695 if (ret)
696 return ret;
697
698 /* 10.1.2.2 step 3 */
699 if (!seed)
700 return ret;
701 }
702
703 return 0;
704 }
705
706 /* 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)707 static int drbg_hmac_generate(struct drbg_state *drbg,
708 unsigned char *buf,
709 unsigned int buflen,
710 struct list_head *addtl)
711 {
712 int len = 0;
713 int ret = 0;
714 struct drbg_string data;
715 LIST_HEAD(datalist);
716
717 /* 10.1.2.5 step 2 */
718 if (addtl && !list_empty(addtl)) {
719 ret = drbg_hmac_update(drbg, addtl, 1);
720 if (ret)
721 return ret;
722 }
723
724 drbg_string_fill(&data, drbg->V, drbg_statelen(drbg));
725 list_add_tail(&data.list, &datalist);
726 while (len < buflen) {
727 unsigned int outlen = 0;
728 /* 10.1.2.5 step 4.1 */
729 ret = drbg_kcapi_hash(drbg, drbg->V, &datalist);
730 if (ret)
731 return ret;
732 outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
733 drbg_blocklen(drbg) : (buflen - len);
734
735 /* 10.1.2.5 step 4.2 */
736 memcpy(buf + len, drbg->V, outlen);
737 len += outlen;
738 }
739
740 /* 10.1.2.5 step 6 */
741 if (addtl && !list_empty(addtl))
742 ret = drbg_hmac_update(drbg, addtl, 1);
743 else
744 ret = drbg_hmac_update(drbg, NULL, 1);
745 if (ret)
746 return ret;
747
748 return len;
749 }
750
751 static const struct drbg_state_ops drbg_hmac_ops = {
752 .update = drbg_hmac_update,
753 .generate = drbg_hmac_generate,
754 .crypto_init = drbg_init_hash_kernel,
755 .crypto_fini = drbg_fini_hash_kernel,
756 };
757 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
758
759 /******************************************************************
760 * Hash DRBG callback functions
761 ******************************************************************/
762
763 #ifdef CONFIG_CRYPTO_DRBG_HASH
764 #define CRYPTO_DRBG_HASH_STRING "HASH "
765 MODULE_ALIAS_CRYPTO("drbg_pr_sha512");
766 MODULE_ALIAS_CRYPTO("drbg_nopr_sha512");
767 MODULE_ALIAS_CRYPTO("drbg_pr_sha384");
768 MODULE_ALIAS_CRYPTO("drbg_nopr_sha384");
769 MODULE_ALIAS_CRYPTO("drbg_pr_sha256");
770 MODULE_ALIAS_CRYPTO("drbg_nopr_sha256");
771 MODULE_ALIAS_CRYPTO("drbg_pr_sha1");
772 MODULE_ALIAS_CRYPTO("drbg_nopr_sha1");
773
774 /*
775 * Increment buffer
776 *
777 * @dst buffer to increment
778 * @add value to add
779 */
drbg_add_buf(unsigned char * dst,size_t dstlen,const unsigned char * add,size_t addlen)780 static inline void drbg_add_buf(unsigned char *dst, size_t dstlen,
781 const unsigned char *add, size_t addlen)
782 {
783 /* implied: dstlen > addlen */
784 unsigned char *dstptr;
785 const unsigned char *addptr;
786 unsigned int remainder = 0;
787 size_t len = addlen;
788
789 dstptr = dst + (dstlen-1);
790 addptr = add + (addlen-1);
791 while (len) {
792 remainder += *dstptr + *addptr;
793 *dstptr = remainder & 0xff;
794 remainder >>= 8;
795 len--; dstptr--; addptr--;
796 }
797 len = dstlen - addlen;
798 while (len && remainder > 0) {
799 remainder = *dstptr + 1;
800 *dstptr = remainder & 0xff;
801 remainder >>= 8;
802 len--; dstptr--;
803 }
804 }
805
806 /*
807 * scratchpad usage: as drbg_hash_update and drbg_hash_df are used
808 * interlinked, the scratchpad is used as follows:
809 * drbg_hash_update
810 * start: drbg->scratchpad
811 * length: drbg_statelen(drbg)
812 * drbg_hash_df:
813 * start: drbg->scratchpad + drbg_statelen(drbg)
814 * length: drbg_blocklen(drbg)
815 *
816 * drbg_hash_process_addtl uses the scratchpad, but fully completes
817 * before either of the functions mentioned before are invoked. Therefore,
818 * drbg_hash_process_addtl does not need to be specifically considered.
819 */
820
821 /* 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)822 static int drbg_hash_df(struct drbg_state *drbg,
823 unsigned char *outval, size_t outlen,
824 struct list_head *entropylist)
825 {
826 int ret = 0;
827 size_t len = 0;
828 unsigned char input[5];
829 unsigned char *tmp = drbg->scratchpad + drbg_statelen(drbg);
830 struct drbg_string data;
831
832 /* 10.4.1 step 3 */
833 input[0] = 1;
834 drbg_cpu_to_be32((outlen * 8), &input[1]);
835
836 /* 10.4.1 step 4.1 -- concatenation of data for input into hash */
837 drbg_string_fill(&data, input, 5);
838 list_add(&data.list, entropylist);
839
840 /* 10.4.1 step 4 */
841 while (len < outlen) {
842 short blocklen = 0;
843 /* 10.4.1 step 4.1 */
844 ret = drbg_kcapi_hash(drbg, tmp, entropylist);
845 if (ret)
846 goto out;
847 /* 10.4.1 step 4.2 */
848 input[0]++;
849 blocklen = (drbg_blocklen(drbg) < (outlen - len)) ?
850 drbg_blocklen(drbg) : (outlen - len);
851 memcpy(outval + len, tmp, blocklen);
852 len += blocklen;
853 }
854
855 out:
856 memset(tmp, 0, drbg_blocklen(drbg));
857 return ret;
858 }
859
860 /* 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)861 static int drbg_hash_update(struct drbg_state *drbg, struct list_head *seed,
862 int reseed)
863 {
864 int ret = 0;
865 struct drbg_string data1, data2;
866 LIST_HEAD(datalist);
867 LIST_HEAD(datalist2);
868 unsigned char *V = drbg->scratchpad;
869 unsigned char prefix = DRBG_PREFIX1;
870
871 if (!seed)
872 return -EINVAL;
873
874 if (reseed) {
875 /* 10.1.1.3 step 1 */
876 memcpy(V, drbg->V, drbg_statelen(drbg));
877 drbg_string_fill(&data1, &prefix, 1);
878 list_add_tail(&data1.list, &datalist);
879 drbg_string_fill(&data2, V, drbg_statelen(drbg));
880 list_add_tail(&data2.list, &datalist);
881 }
882 list_splice_tail(seed, &datalist);
883
884 /* 10.1.1.2 / 10.1.1.3 step 2 and 3 */
885 ret = drbg_hash_df(drbg, drbg->V, drbg_statelen(drbg), &datalist);
886 if (ret)
887 goto out;
888
889 /* 10.1.1.2 / 10.1.1.3 step 4 */
890 prefix = DRBG_PREFIX0;
891 drbg_string_fill(&data1, &prefix, 1);
892 list_add_tail(&data1.list, &datalist2);
893 drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
894 list_add_tail(&data2.list, &datalist2);
895 /* 10.1.1.2 / 10.1.1.3 step 4 */
896 ret = drbg_hash_df(drbg, drbg->C, drbg_statelen(drbg), &datalist2);
897
898 out:
899 memset(drbg->scratchpad, 0, drbg_statelen(drbg));
900 return ret;
901 }
902
903 /* processing of additional information string for Hash DRBG */
drbg_hash_process_addtl(struct drbg_state * drbg,struct list_head * addtl)904 static int drbg_hash_process_addtl(struct drbg_state *drbg,
905 struct list_head *addtl)
906 {
907 int ret = 0;
908 struct drbg_string data1, data2;
909 LIST_HEAD(datalist);
910 unsigned char prefix = DRBG_PREFIX2;
911
912 /* 10.1.1.4 step 2 */
913 if (!addtl || list_empty(addtl))
914 return 0;
915
916 /* 10.1.1.4 step 2a */
917 drbg_string_fill(&data1, &prefix, 1);
918 drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
919 list_add_tail(&data1.list, &datalist);
920 list_add_tail(&data2.list, &datalist);
921 list_splice_tail(addtl, &datalist);
922 ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
923 if (ret)
924 goto out;
925
926 /* 10.1.1.4 step 2b */
927 drbg_add_buf(drbg->V, drbg_statelen(drbg),
928 drbg->scratchpad, drbg_blocklen(drbg));
929
930 out:
931 memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
932 return ret;
933 }
934
935 /* Hashgen defined in 10.1.1.4 */
drbg_hash_hashgen(struct drbg_state * drbg,unsigned char * buf,unsigned int buflen)936 static int drbg_hash_hashgen(struct drbg_state *drbg,
937 unsigned char *buf,
938 unsigned int buflen)
939 {
940 int len = 0;
941 int ret = 0;
942 unsigned char *src = drbg->scratchpad;
943 unsigned char *dst = drbg->scratchpad + drbg_statelen(drbg);
944 struct drbg_string data;
945 LIST_HEAD(datalist);
946
947 /* 10.1.1.4 step hashgen 2 */
948 memcpy(src, drbg->V, drbg_statelen(drbg));
949
950 drbg_string_fill(&data, src, drbg_statelen(drbg));
951 list_add_tail(&data.list, &datalist);
952 while (len < buflen) {
953 unsigned int outlen = 0;
954 /* 10.1.1.4 step hashgen 4.1 */
955 ret = drbg_kcapi_hash(drbg, dst, &datalist);
956 if (ret) {
957 len = ret;
958 goto out;
959 }
960 outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
961 drbg_blocklen(drbg) : (buflen - len);
962 /* 10.1.1.4 step hashgen 4.2 */
963 memcpy(buf + len, dst, outlen);
964 len += outlen;
965 /* 10.1.1.4 hashgen step 4.3 */
966 if (len < buflen)
967 crypto_inc(src, drbg_statelen(drbg));
968 }
969
970 out:
971 memset(drbg->scratchpad, 0,
972 (drbg_statelen(drbg) + drbg_blocklen(drbg)));
973 return len;
974 }
975
976 /* 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)977 static int drbg_hash_generate(struct drbg_state *drbg,
978 unsigned char *buf, unsigned int buflen,
979 struct list_head *addtl)
980 {
981 int len = 0;
982 int ret = 0;
983 union {
984 unsigned char req[8];
985 __be64 req_int;
986 } u;
987 unsigned char prefix = DRBG_PREFIX3;
988 struct drbg_string data1, data2;
989 LIST_HEAD(datalist);
990
991 /* 10.1.1.4 step 2 */
992 ret = drbg_hash_process_addtl(drbg, addtl);
993 if (ret)
994 return ret;
995 /* 10.1.1.4 step 3 */
996 len = drbg_hash_hashgen(drbg, buf, buflen);
997
998 /* this is the value H as documented in 10.1.1.4 */
999 /* 10.1.1.4 step 4 */
1000 drbg_string_fill(&data1, &prefix, 1);
1001 list_add_tail(&data1.list, &datalist);
1002 drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
1003 list_add_tail(&data2.list, &datalist);
1004 ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
1005 if (ret) {
1006 len = ret;
1007 goto out;
1008 }
1009
1010 /* 10.1.1.4 step 5 */
1011 drbg_add_buf(drbg->V, drbg_statelen(drbg),
1012 drbg->scratchpad, drbg_blocklen(drbg));
1013 drbg_add_buf(drbg->V, drbg_statelen(drbg),
1014 drbg->C, drbg_statelen(drbg));
1015 u.req_int = cpu_to_be64(drbg->reseed_ctr);
1016 drbg_add_buf(drbg->V, drbg_statelen(drbg), u.req, 8);
1017
1018 out:
1019 memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
1020 return len;
1021 }
1022
1023 /*
1024 * scratchpad usage: as update and generate are used isolated, both
1025 * can use the scratchpad
1026 */
1027 static const struct drbg_state_ops drbg_hash_ops = {
1028 .update = drbg_hash_update,
1029 .generate = drbg_hash_generate,
1030 .crypto_init = drbg_init_hash_kernel,
1031 .crypto_fini = drbg_fini_hash_kernel,
1032 };
1033 #endif /* CONFIG_CRYPTO_DRBG_HASH */
1034
1035 /******************************************************************
1036 * Functions common for DRBG implementations
1037 ******************************************************************/
1038
__drbg_seed(struct drbg_state * drbg,struct list_head * seed,int reseed,enum drbg_seed_state new_seed_state)1039 static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed,
1040 int reseed, enum drbg_seed_state new_seed_state)
1041 {
1042 int ret = drbg->d_ops->update(drbg, seed, reseed);
1043
1044 if (ret)
1045 return ret;
1046
1047 drbg->seeded = new_seed_state;
1048 drbg->last_seed_time = jiffies;
1049 /* 10.1.1.2 / 10.1.1.3 step 5 */
1050 drbg->reseed_ctr = 1;
1051
1052 switch (drbg->seeded) {
1053 case DRBG_SEED_STATE_UNSEEDED:
1054 /* Impossible, but handle it to silence compiler warnings. */
1055 fallthrough;
1056 case DRBG_SEED_STATE_PARTIAL:
1057 /*
1058 * Require frequent reseeds until the seed source is
1059 * fully initialized.
1060 */
1061 drbg->reseed_threshold = 50;
1062 break;
1063
1064 case DRBG_SEED_STATE_FULL:
1065 /*
1066 * Seed source has become fully initialized, frequent
1067 * reseeds no longer required.
1068 */
1069 drbg->reseed_threshold = drbg_max_requests(drbg);
1070 break;
1071 }
1072
1073 return ret;
1074 }
1075
drbg_get_random_bytes(struct drbg_state * drbg,unsigned char * entropy,unsigned int entropylen)1076 static inline int drbg_get_random_bytes(struct drbg_state *drbg,
1077 unsigned char *entropy,
1078 unsigned int entropylen)
1079 {
1080 int ret;
1081
1082 do {
1083 get_random_bytes(entropy, entropylen);
1084 ret = drbg_fips_continuous_test(drbg, entropy);
1085 if (ret && ret != -EAGAIN)
1086 return ret;
1087 } while (ret);
1088
1089 return 0;
1090 }
1091
drbg_seed_from_random(struct drbg_state * drbg)1092 static int drbg_seed_from_random(struct drbg_state *drbg)
1093 {
1094 struct drbg_string data;
1095 LIST_HEAD(seedlist);
1096 unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
1097 unsigned char entropy[32];
1098 int ret;
1099
1100 BUG_ON(!entropylen);
1101 BUG_ON(entropylen > sizeof(entropy));
1102
1103 drbg_string_fill(&data, entropy, entropylen);
1104 list_add_tail(&data.list, &seedlist);
1105
1106 ret = drbg_get_random_bytes(drbg, entropy, entropylen);
1107 if (ret)
1108 goto out;
1109
1110 ret = __drbg_seed(drbg, &seedlist, true, DRBG_SEED_STATE_FULL);
1111
1112 out:
1113 memzero_explicit(entropy, entropylen);
1114 return ret;
1115 }
1116
drbg_nopr_reseed_interval_elapsed(struct drbg_state * drbg)1117 static bool drbg_nopr_reseed_interval_elapsed(struct drbg_state *drbg)
1118 {
1119 unsigned long next_reseed;
1120
1121 /* Don't ever reseed from get_random_bytes() in test mode. */
1122 if (list_empty(&drbg->test_data.list))
1123 return false;
1124
1125 /*
1126 * Obtain fresh entropy for the nopr DRBGs after 300s have
1127 * elapsed in order to still achieve sort of partial
1128 * prediction resistance over the time domain at least. Note
1129 * that the period of 300s has been chosen to match the
1130 * CRNG_RESEED_INTERVAL of the get_random_bytes()' chacha
1131 * rngs.
1132 */
1133 next_reseed = drbg->last_seed_time + 300 * HZ;
1134 return time_after(jiffies, next_reseed);
1135 }
1136
1137 /*
1138 * Seeding or reseeding of the DRBG
1139 *
1140 * @drbg: DRBG state struct
1141 * @pers: personalization / additional information buffer
1142 * @reseed: 0 for initial seed process, 1 for reseeding
1143 *
1144 * return:
1145 * 0 on success
1146 * error value otherwise
1147 */
drbg_seed(struct drbg_state * drbg,struct drbg_string * pers,bool reseed)1148 static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
1149 bool reseed)
1150 {
1151 int ret;
1152 unsigned char entropy[((32 + 16) * 2)];
1153 unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
1154 struct drbg_string data1;
1155 LIST_HEAD(seedlist);
1156 enum drbg_seed_state new_seed_state = DRBG_SEED_STATE_FULL;
1157
1158 /* 9.1 / 9.2 / 9.3.1 step 3 */
1159 if (pers && pers->len > (drbg_max_addtl(drbg))) {
1160 pr_devel("DRBG: personalization string too long %zu\n",
1161 pers->len);
1162 return -EINVAL;
1163 }
1164
1165 if (list_empty(&drbg->test_data.list)) {
1166 drbg_string_fill(&data1, drbg->test_data.buf,
1167 drbg->test_data.len);
1168 pr_devel("DRBG: using test entropy\n");
1169 } else {
1170 /*
1171 * Gather entropy equal to the security strength of the DRBG.
1172 * With a derivation function, a nonce is required in addition
1173 * to the entropy. A nonce must be at least 1/2 of the security
1174 * strength of the DRBG in size. Thus, entropy + nonce is 3/2
1175 * of the strength. The consideration of a nonce is only
1176 * applicable during initial seeding.
1177 */
1178 BUG_ON(!entropylen);
1179 if (!reseed)
1180 entropylen = ((entropylen + 1) / 2) * 3;
1181 BUG_ON((entropylen * 2) > sizeof(entropy));
1182
1183 /* Get seed from in-kernel /dev/urandom */
1184 if (!rng_is_initialized())
1185 new_seed_state = DRBG_SEED_STATE_PARTIAL;
1186
1187 ret = drbg_get_random_bytes(drbg, entropy, entropylen);
1188 if (ret)
1189 goto out;
1190
1191 if (!drbg->jent) {
1192 drbg_string_fill(&data1, entropy, entropylen);
1193 pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
1194 entropylen);
1195 } else {
1196 /*
1197 * Get seed from Jitter RNG, failures are
1198 * fatal only in FIPS mode.
1199 */
1200 ret = crypto_rng_get_bytes(drbg->jent,
1201 entropy + entropylen,
1202 entropylen);
1203 if (fips_enabled && ret) {
1204 pr_devel("DRBG: jent failed with %d\n", ret);
1205
1206 /*
1207 * Do not treat the transient failure of the
1208 * Jitter RNG as an error that needs to be
1209 * reported. The combined number of the
1210 * maximum reseed threshold times the maximum
1211 * number of Jitter RNG transient errors is
1212 * less than the reseed threshold required by
1213 * SP800-90A allowing us to treat the
1214 * transient errors as such.
1215 *
1216 * However, we mandate that at least the first
1217 * seeding operation must succeed with the
1218 * Jitter RNG.
1219 */
1220 if (!reseed || ret != -EAGAIN)
1221 goto out;
1222 }
1223
1224 drbg_string_fill(&data1, entropy, entropylen * 2);
1225 pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
1226 entropylen * 2);
1227 }
1228 }
1229 list_add_tail(&data1.list, &seedlist);
1230
1231 /*
1232 * concatenation of entropy with personalization str / addtl input)
1233 * the variable pers is directly handed in by the caller, so check its
1234 * contents whether it is appropriate
1235 */
1236 if (pers && pers->buf && 0 < pers->len) {
1237 list_add_tail(&pers->list, &seedlist);
1238 pr_devel("DRBG: using personalization string\n");
1239 }
1240
1241 if (!reseed) {
1242 memset(drbg->V, 0, drbg_statelen(drbg));
1243 memset(drbg->C, 0, drbg_statelen(drbg));
1244 }
1245
1246 ret = __drbg_seed(drbg, &seedlist, reseed, new_seed_state);
1247
1248 out:
1249 memzero_explicit(entropy, entropylen * 2);
1250
1251 return ret;
1252 }
1253
1254 /* Free all substructures in a DRBG state without the DRBG state structure */
drbg_dealloc_state(struct drbg_state * drbg)1255 static inline void drbg_dealloc_state(struct drbg_state *drbg)
1256 {
1257 if (!drbg)
1258 return;
1259 kfree_sensitive(drbg->Vbuf);
1260 drbg->Vbuf = NULL;
1261 drbg->V = NULL;
1262 kfree_sensitive(drbg->Cbuf);
1263 drbg->Cbuf = NULL;
1264 drbg->C = NULL;
1265 kfree_sensitive(drbg->scratchpadbuf);
1266 drbg->scratchpadbuf = NULL;
1267 drbg->reseed_ctr = 0;
1268 drbg->d_ops = NULL;
1269 drbg->core = NULL;
1270 if (IS_ENABLED(CONFIG_CRYPTO_FIPS)) {
1271 kfree_sensitive(drbg->prev);
1272 drbg->prev = NULL;
1273 drbg->fips_primed = false;
1274 }
1275 }
1276
1277 /*
1278 * Allocate all sub-structures for a DRBG state.
1279 * The DRBG state structure must already be allocated.
1280 */
drbg_alloc_state(struct drbg_state * drbg)1281 static inline int drbg_alloc_state(struct drbg_state *drbg)
1282 {
1283 int ret = -ENOMEM;
1284 unsigned int sb_size = 0;
1285
1286 switch (drbg->core->flags & DRBG_TYPE_MASK) {
1287 #ifdef CONFIG_CRYPTO_DRBG_HMAC
1288 case DRBG_HMAC:
1289 drbg->d_ops = &drbg_hmac_ops;
1290 break;
1291 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
1292 #ifdef CONFIG_CRYPTO_DRBG_HASH
1293 case DRBG_HASH:
1294 drbg->d_ops = &drbg_hash_ops;
1295 break;
1296 #endif /* CONFIG_CRYPTO_DRBG_HASH */
1297 #ifdef CONFIG_CRYPTO_DRBG_CTR
1298 case DRBG_CTR:
1299 drbg->d_ops = &drbg_ctr_ops;
1300 break;
1301 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1302 default:
1303 ret = -EOPNOTSUPP;
1304 goto err;
1305 }
1306
1307 ret = drbg->d_ops->crypto_init(drbg);
1308 if (ret < 0)
1309 goto err;
1310
1311 drbg->Vbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL);
1312 if (!drbg->Vbuf) {
1313 ret = -ENOMEM;
1314 goto fini;
1315 }
1316 drbg->V = PTR_ALIGN(drbg->Vbuf, ret + 1);
1317 drbg->Cbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL);
1318 if (!drbg->Cbuf) {
1319 ret = -ENOMEM;
1320 goto fini;
1321 }
1322 drbg->C = PTR_ALIGN(drbg->Cbuf, ret + 1);
1323 /* scratchpad is only generated for CTR and Hash */
1324 if (drbg->core->flags & DRBG_HMAC)
1325 sb_size = 0;
1326 else if (drbg->core->flags & DRBG_CTR)
1327 sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg) + /* temp */
1328 drbg_statelen(drbg) + /* df_data */
1329 drbg_blocklen(drbg) + /* pad */
1330 drbg_blocklen(drbg) + /* iv */
1331 drbg_statelen(drbg) + drbg_blocklen(drbg); /* temp */
1332 else
1333 sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg);
1334
1335 if (0 < sb_size) {
1336 drbg->scratchpadbuf = kzalloc(sb_size + ret, GFP_KERNEL);
1337 if (!drbg->scratchpadbuf) {
1338 ret = -ENOMEM;
1339 goto fini;
1340 }
1341 drbg->scratchpad = PTR_ALIGN(drbg->scratchpadbuf, ret + 1);
1342 }
1343
1344 if (IS_ENABLED(CONFIG_CRYPTO_FIPS)) {
1345 drbg->prev = kzalloc(drbg_sec_strength(drbg->core->flags),
1346 GFP_KERNEL);
1347 if (!drbg->prev) {
1348 ret = -ENOMEM;
1349 goto fini;
1350 }
1351 drbg->fips_primed = false;
1352 }
1353
1354 return 0;
1355
1356 fini:
1357 drbg->d_ops->crypto_fini(drbg);
1358 err:
1359 drbg_dealloc_state(drbg);
1360 return ret;
1361 }
1362
1363 /*************************************************************************
1364 * DRBG interface functions
1365 *************************************************************************/
1366
1367 /*
1368 * DRBG generate function as required by SP800-90A - this function
1369 * generates random numbers
1370 *
1371 * @drbg DRBG state handle
1372 * @buf Buffer where to store the random numbers -- the buffer must already
1373 * be pre-allocated by caller
1374 * @buflen Length of output buffer - this value defines the number of random
1375 * bytes pulled from DRBG
1376 * @addtl Additional input that is mixed into state, may be NULL -- note
1377 * the entropy is pulled by the DRBG internally unconditionally
1378 * as defined in SP800-90A. The additional input is mixed into
1379 * the state in addition to the pulled entropy.
1380 *
1381 * return: 0 when all bytes are generated; < 0 in case of an error
1382 */
drbg_generate(struct drbg_state * drbg,unsigned char * buf,unsigned int buflen,struct drbg_string * addtl)1383 static int drbg_generate(struct drbg_state *drbg,
1384 unsigned char *buf, unsigned int buflen,
1385 struct drbg_string *addtl)
1386 {
1387 int len = 0;
1388 LIST_HEAD(addtllist);
1389
1390 if (!drbg->core) {
1391 pr_devel("DRBG: not yet seeded\n");
1392 return -EINVAL;
1393 }
1394 if (0 == buflen || !buf) {
1395 pr_devel("DRBG: no output buffer provided\n");
1396 return -EINVAL;
1397 }
1398 if (addtl && NULL == addtl->buf && 0 < addtl->len) {
1399 pr_devel("DRBG: wrong format of additional information\n");
1400 return -EINVAL;
1401 }
1402
1403 /* 9.3.1 step 2 */
1404 len = -EINVAL;
1405 if (buflen > (drbg_max_request_bytes(drbg))) {
1406 pr_devel("DRBG: requested random numbers too large %u\n",
1407 buflen);
1408 goto err;
1409 }
1410
1411 /* 9.3.1 step 3 is implicit with the chosen DRBG */
1412
1413 /* 9.3.1 step 4 */
1414 if (addtl && addtl->len > (drbg_max_addtl(drbg))) {
1415 pr_devel("DRBG: additional information string too long %zu\n",
1416 addtl->len);
1417 goto err;
1418 }
1419 /* 9.3.1 step 5 is implicit with the chosen DRBG */
1420
1421 /*
1422 * 9.3.1 step 6 and 9 supplemented by 9.3.2 step c is implemented
1423 * here. The spec is a bit convoluted here, we make it simpler.
1424 */
1425 if (drbg->reseed_threshold < drbg->reseed_ctr)
1426 drbg->seeded = DRBG_SEED_STATE_UNSEEDED;
1427
1428 if (drbg->pr || drbg->seeded == DRBG_SEED_STATE_UNSEEDED) {
1429 pr_devel("DRBG: reseeding before generation (prediction "
1430 "resistance: %s, state %s)\n",
1431 drbg->pr ? "true" : "false",
1432 (drbg->seeded == DRBG_SEED_STATE_FULL ?
1433 "seeded" : "unseeded"));
1434 /* 9.3.1 steps 7.1 through 7.3 */
1435 len = drbg_seed(drbg, addtl, true);
1436 if (len)
1437 goto err;
1438 /* 9.3.1 step 7.4 */
1439 addtl = NULL;
1440 } else if (rng_is_initialized() &&
1441 (drbg->seeded == DRBG_SEED_STATE_PARTIAL ||
1442 drbg_nopr_reseed_interval_elapsed(drbg))) {
1443 len = drbg_seed_from_random(drbg);
1444 if (len)
1445 goto err;
1446 }
1447
1448 if (addtl && 0 < addtl->len)
1449 list_add_tail(&addtl->list, &addtllist);
1450 /* 9.3.1 step 8 and 10 */
1451 len = drbg->d_ops->generate(drbg, buf, buflen, &addtllist);
1452
1453 /* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */
1454 drbg->reseed_ctr++;
1455 if (0 >= len)
1456 goto err;
1457
1458 /*
1459 * Section 11.3.3 requires to re-perform self tests after some
1460 * generated random numbers. The chosen value after which self
1461 * test is performed is arbitrary, but it should be reasonable.
1462 * However, we do not perform the self tests because of the following
1463 * reasons: it is mathematically impossible that the initial self tests
1464 * were successfully and the following are not. If the initial would
1465 * pass and the following would not, the kernel integrity is violated.
1466 * In this case, the entire kernel operation is questionable and it
1467 * is unlikely that the integrity violation only affects the
1468 * correct operation of the DRBG.
1469 *
1470 * Albeit the following code is commented out, it is provided in
1471 * case somebody has a need to implement the test of 11.3.3.
1472 */
1473 #if 0
1474 if (drbg->reseed_ctr && !(drbg->reseed_ctr % 4096)) {
1475 int err = 0;
1476 pr_devel("DRBG: start to perform self test\n");
1477 if (drbg->core->flags & DRBG_HMAC)
1478 err = alg_test("drbg_pr_hmac_sha256",
1479 "drbg_pr_hmac_sha256", 0, 0);
1480 else if (drbg->core->flags & DRBG_CTR)
1481 err = alg_test("drbg_pr_ctr_aes128",
1482 "drbg_pr_ctr_aes128", 0, 0);
1483 else
1484 err = alg_test("drbg_pr_sha256",
1485 "drbg_pr_sha256", 0, 0);
1486 if (err) {
1487 pr_err("DRBG: periodical self test failed\n");
1488 /*
1489 * uninstantiate implies that from now on, only errors
1490 * are returned when reusing this DRBG cipher handle
1491 */
1492 drbg_uninstantiate(drbg);
1493 return 0;
1494 } else {
1495 pr_devel("DRBG: self test successful\n");
1496 }
1497 }
1498 #endif
1499
1500 /*
1501 * All operations were successful, return 0 as mandated by
1502 * the kernel crypto API interface.
1503 */
1504 len = 0;
1505 err:
1506 return len;
1507 }
1508
1509 /*
1510 * Wrapper around drbg_generate which can pull arbitrary long strings
1511 * from the DRBG without hitting the maximum request limitation.
1512 *
1513 * Parameters: see drbg_generate
1514 * Return codes: see drbg_generate -- if one drbg_generate request fails,
1515 * the entire drbg_generate_long request fails
1516 */
drbg_generate_long(struct drbg_state * drbg,unsigned char * buf,unsigned int buflen,struct drbg_string * addtl)1517 static int drbg_generate_long(struct drbg_state *drbg,
1518 unsigned char *buf, unsigned int buflen,
1519 struct drbg_string *addtl)
1520 {
1521 unsigned int len = 0;
1522 unsigned int slice = 0;
1523 do {
1524 int err = 0;
1525 unsigned int chunk = 0;
1526 slice = ((buflen - len) / drbg_max_request_bytes(drbg));
1527 chunk = slice ? drbg_max_request_bytes(drbg) : (buflen - len);
1528 mutex_lock(&drbg->drbg_mutex);
1529 err = drbg_generate(drbg, buf + len, chunk, addtl);
1530 mutex_unlock(&drbg->drbg_mutex);
1531 if (0 > err)
1532 return err;
1533 len += chunk;
1534 } while (slice > 0 && (len < buflen));
1535 return 0;
1536 }
1537
drbg_prepare_hrng(struct drbg_state * drbg)1538 static int drbg_prepare_hrng(struct drbg_state *drbg)
1539 {
1540 /* We do not need an HRNG in test mode. */
1541 if (list_empty(&drbg->test_data.list))
1542 return 0;
1543
1544 drbg->jent = crypto_alloc_rng("jitterentropy_rng", 0, 0);
1545 if (IS_ERR(drbg->jent)) {
1546 const int err = PTR_ERR(drbg->jent);
1547
1548 drbg->jent = NULL;
1549 if (fips_enabled || err != -ENOENT)
1550 return err;
1551 pr_info("DRBG: Continuing without Jitter RNG\n");
1552 }
1553
1554 return 0;
1555 }
1556
1557 /*
1558 * DRBG instantiation function as required by SP800-90A - this function
1559 * sets up the DRBG handle, performs the initial seeding and all sanity
1560 * checks required by SP800-90A
1561 *
1562 * @drbg memory of state -- if NULL, new memory is allocated
1563 * @pers Personalization string that is mixed into state, may be NULL -- note
1564 * the entropy is pulled by the DRBG internally unconditionally
1565 * as defined in SP800-90A. The additional input is mixed into
1566 * the state in addition to the pulled entropy.
1567 * @coreref reference to core
1568 * @pr prediction resistance enabled
1569 *
1570 * return
1571 * 0 on success
1572 * error value otherwise
1573 */
drbg_instantiate(struct drbg_state * drbg,struct drbg_string * pers,int coreref,bool pr)1574 static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers,
1575 int coreref, bool pr)
1576 {
1577 int ret;
1578 bool reseed = true;
1579
1580 pr_devel("DRBG: Initializing DRBG core %d with prediction resistance "
1581 "%s\n", coreref, pr ? "enabled" : "disabled");
1582 mutex_lock(&drbg->drbg_mutex);
1583
1584 /* 9.1 step 1 is implicit with the selected DRBG type */
1585
1586 /*
1587 * 9.1 step 2 is implicit as caller can select prediction resistance
1588 * and the flag is copied into drbg->flags --
1589 * all DRBG types support prediction resistance
1590 */
1591
1592 /* 9.1 step 4 is implicit in drbg_sec_strength */
1593
1594 if (!drbg->core) {
1595 drbg->core = &drbg_cores[coreref];
1596 drbg->pr = pr;
1597 drbg->seeded = DRBG_SEED_STATE_UNSEEDED;
1598 drbg->last_seed_time = 0;
1599 drbg->reseed_threshold = drbg_max_requests(drbg);
1600
1601 ret = drbg_alloc_state(drbg);
1602 if (ret)
1603 goto unlock;
1604
1605 ret = drbg_prepare_hrng(drbg);
1606 if (ret)
1607 goto free_everything;
1608
1609 reseed = false;
1610 }
1611
1612 ret = drbg_seed(drbg, pers, reseed);
1613
1614 if (ret && !reseed)
1615 goto free_everything;
1616
1617 mutex_unlock(&drbg->drbg_mutex);
1618 return ret;
1619
1620 unlock:
1621 mutex_unlock(&drbg->drbg_mutex);
1622 return ret;
1623
1624 free_everything:
1625 mutex_unlock(&drbg->drbg_mutex);
1626 drbg_uninstantiate(drbg);
1627 return ret;
1628 }
1629
1630 /*
1631 * DRBG uninstantiate function as required by SP800-90A - this function
1632 * frees all buffers and the DRBG handle
1633 *
1634 * @drbg DRBG state handle
1635 *
1636 * return
1637 * 0 on success
1638 */
drbg_uninstantiate(struct drbg_state * drbg)1639 static int drbg_uninstantiate(struct drbg_state *drbg)
1640 {
1641 if (!IS_ERR_OR_NULL(drbg->jent))
1642 crypto_free_rng(drbg->jent);
1643 drbg->jent = NULL;
1644
1645 if (drbg->d_ops)
1646 drbg->d_ops->crypto_fini(drbg);
1647 drbg_dealloc_state(drbg);
1648 /* no scrubbing of test_data -- this shall survive an uninstantiate */
1649 return 0;
1650 }
1651
1652 /*
1653 * Helper function for setting the test data in the DRBG
1654 *
1655 * @drbg DRBG state handle
1656 * @data test data
1657 * @len test data length
1658 */
drbg_kcapi_set_entropy(struct crypto_rng * tfm,const u8 * data,unsigned int len)1659 static void drbg_kcapi_set_entropy(struct crypto_rng *tfm,
1660 const u8 *data, unsigned int len)
1661 {
1662 struct drbg_state *drbg = crypto_rng_ctx(tfm);
1663
1664 mutex_lock(&drbg->drbg_mutex);
1665 drbg_string_fill(&drbg->test_data, data, len);
1666 mutex_unlock(&drbg->drbg_mutex);
1667 }
1668
1669 /***************************************************************
1670 * Kernel crypto API cipher invocations requested by DRBG
1671 ***************************************************************/
1672
1673 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
1674 struct sdesc {
1675 struct shash_desc shash;
1676 char ctx[];
1677 };
1678
drbg_init_hash_kernel(struct drbg_state * drbg)1679 static int drbg_init_hash_kernel(struct drbg_state *drbg)
1680 {
1681 struct sdesc *sdesc;
1682 struct crypto_shash *tfm;
1683
1684 tfm = crypto_alloc_shash(drbg->core->backend_cra_name, 0, 0);
1685 if (IS_ERR(tfm)) {
1686 pr_info("DRBG: could not allocate digest TFM handle: %s\n",
1687 drbg->core->backend_cra_name);
1688 return PTR_ERR(tfm);
1689 }
1690 BUG_ON(drbg_blocklen(drbg) != crypto_shash_digestsize(tfm));
1691 sdesc = kzalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm),
1692 GFP_KERNEL);
1693 if (!sdesc) {
1694 crypto_free_shash(tfm);
1695 return -ENOMEM;
1696 }
1697
1698 sdesc->shash.tfm = tfm;
1699 drbg->priv_data = sdesc;
1700
1701 return crypto_shash_alignmask(tfm);
1702 }
1703
drbg_fini_hash_kernel(struct drbg_state * drbg)1704 static int drbg_fini_hash_kernel(struct drbg_state *drbg)
1705 {
1706 struct sdesc *sdesc = drbg->priv_data;
1707 if (sdesc) {
1708 crypto_free_shash(sdesc->shash.tfm);
1709 kfree_sensitive(sdesc);
1710 }
1711 drbg->priv_data = NULL;
1712 return 0;
1713 }
1714
drbg_kcapi_hmacsetkey(struct drbg_state * drbg,const unsigned char * key)1715 static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
1716 const unsigned char *key)
1717 {
1718 struct sdesc *sdesc = drbg->priv_data;
1719
1720 crypto_shash_setkey(sdesc->shash.tfm, key, drbg_statelen(drbg));
1721 }
1722
drbg_kcapi_hash(struct drbg_state * drbg,unsigned char * outval,const struct list_head * in)1723 static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
1724 const struct list_head *in)
1725 {
1726 struct sdesc *sdesc = drbg->priv_data;
1727 struct drbg_string *input = NULL;
1728
1729 crypto_shash_init(&sdesc->shash);
1730 list_for_each_entry(input, in, list)
1731 crypto_shash_update(&sdesc->shash, input->buf, input->len);
1732 return crypto_shash_final(&sdesc->shash, outval);
1733 }
1734 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
1735
1736 #ifdef CONFIG_CRYPTO_DRBG_CTR
drbg_fini_sym_kernel(struct drbg_state * drbg)1737 static int drbg_fini_sym_kernel(struct drbg_state *drbg)
1738 {
1739 struct crypto_cipher *tfm =
1740 (struct crypto_cipher *)drbg->priv_data;
1741 if (tfm)
1742 crypto_free_cipher(tfm);
1743 drbg->priv_data = NULL;
1744
1745 if (drbg->ctr_handle)
1746 crypto_free_skcipher(drbg->ctr_handle);
1747 drbg->ctr_handle = NULL;
1748
1749 if (drbg->ctr_req)
1750 skcipher_request_free(drbg->ctr_req);
1751 drbg->ctr_req = NULL;
1752
1753 kfree(drbg->outscratchpadbuf);
1754 drbg->outscratchpadbuf = NULL;
1755
1756 return 0;
1757 }
1758
drbg_init_sym_kernel(struct drbg_state * drbg)1759 static int drbg_init_sym_kernel(struct drbg_state *drbg)
1760 {
1761 struct crypto_cipher *tfm;
1762 struct crypto_skcipher *sk_tfm;
1763 struct skcipher_request *req;
1764 unsigned int alignmask;
1765 char ctr_name[CRYPTO_MAX_ALG_NAME];
1766
1767 tfm = crypto_alloc_cipher(drbg->core->backend_cra_name, 0, 0);
1768 if (IS_ERR(tfm)) {
1769 pr_info("DRBG: could not allocate cipher TFM handle: %s\n",
1770 drbg->core->backend_cra_name);
1771 return PTR_ERR(tfm);
1772 }
1773 BUG_ON(drbg_blocklen(drbg) != crypto_cipher_blocksize(tfm));
1774 drbg->priv_data = tfm;
1775
1776 if (snprintf(ctr_name, CRYPTO_MAX_ALG_NAME, "ctr(%s)",
1777 drbg->core->backend_cra_name) >= CRYPTO_MAX_ALG_NAME) {
1778 drbg_fini_sym_kernel(drbg);
1779 return -EINVAL;
1780 }
1781 sk_tfm = crypto_alloc_skcipher(ctr_name, 0, 0);
1782 if (IS_ERR(sk_tfm)) {
1783 pr_info("DRBG: could not allocate CTR cipher TFM handle: %s\n",
1784 ctr_name);
1785 drbg_fini_sym_kernel(drbg);
1786 return PTR_ERR(sk_tfm);
1787 }
1788 drbg->ctr_handle = sk_tfm;
1789 crypto_init_wait(&drbg->ctr_wait);
1790
1791 req = skcipher_request_alloc(sk_tfm, GFP_KERNEL);
1792 if (!req) {
1793 pr_info("DRBG: could not allocate request queue\n");
1794 drbg_fini_sym_kernel(drbg);
1795 return -ENOMEM;
1796 }
1797 drbg->ctr_req = req;
1798 skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
1799 CRYPTO_TFM_REQ_MAY_SLEEP,
1800 crypto_req_done, &drbg->ctr_wait);
1801
1802 alignmask = crypto_skcipher_alignmask(sk_tfm);
1803 drbg->outscratchpadbuf = kmalloc(DRBG_OUTSCRATCHLEN + alignmask,
1804 GFP_KERNEL);
1805 if (!drbg->outscratchpadbuf) {
1806 drbg_fini_sym_kernel(drbg);
1807 return -ENOMEM;
1808 }
1809 drbg->outscratchpad = (u8 *)PTR_ALIGN(drbg->outscratchpadbuf,
1810 alignmask + 1);
1811
1812 sg_init_table(&drbg->sg_in, 1);
1813 sg_init_one(&drbg->sg_out, drbg->outscratchpad, DRBG_OUTSCRATCHLEN);
1814
1815 return alignmask;
1816 }
1817
drbg_kcapi_symsetkey(struct drbg_state * drbg,const unsigned char * key)1818 static void drbg_kcapi_symsetkey(struct drbg_state *drbg,
1819 const unsigned char *key)
1820 {
1821 struct crypto_cipher *tfm = drbg->priv_data;
1822
1823 crypto_cipher_setkey(tfm, key, (drbg_keylen(drbg)));
1824 }
1825
drbg_kcapi_sym(struct drbg_state * drbg,unsigned char * outval,const struct drbg_string * in)1826 static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
1827 const struct drbg_string *in)
1828 {
1829 struct crypto_cipher *tfm = drbg->priv_data;
1830
1831 /* there is only component in *in */
1832 BUG_ON(in->len < drbg_blocklen(drbg));
1833 crypto_cipher_encrypt_one(tfm, outval, in->buf);
1834 return 0;
1835 }
1836
drbg_kcapi_sym_ctr(struct drbg_state * drbg,u8 * inbuf,u32 inlen,u8 * outbuf,u32 outlen)1837 static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
1838 u8 *inbuf, u32 inlen,
1839 u8 *outbuf, u32 outlen)
1840 {
1841 struct scatterlist *sg_in = &drbg->sg_in, *sg_out = &drbg->sg_out;
1842 u32 scratchpad_use = min_t(u32, outlen, DRBG_OUTSCRATCHLEN);
1843 int ret;
1844
1845 if (inbuf) {
1846 /* Use caller-provided input buffer */
1847 sg_set_buf(sg_in, inbuf, inlen);
1848 } else {
1849 /* Use scratchpad for in-place operation */
1850 inlen = scratchpad_use;
1851 memset(drbg->outscratchpad, 0, scratchpad_use);
1852 sg_set_buf(sg_in, drbg->outscratchpad, scratchpad_use);
1853 }
1854
1855 while (outlen) {
1856 u32 cryptlen = min3(inlen, outlen, (u32)DRBG_OUTSCRATCHLEN);
1857
1858 /* Output buffer may not be valid for SGL, use scratchpad */
1859 skcipher_request_set_crypt(drbg->ctr_req, sg_in, sg_out,
1860 cryptlen, drbg->V);
1861 ret = crypto_wait_req(crypto_skcipher_encrypt(drbg->ctr_req),
1862 &drbg->ctr_wait);
1863 if (ret)
1864 goto out;
1865
1866 crypto_init_wait(&drbg->ctr_wait);
1867
1868 memcpy(outbuf, drbg->outscratchpad, cryptlen);
1869 memzero_explicit(drbg->outscratchpad, cryptlen);
1870
1871 outlen -= cryptlen;
1872 outbuf += cryptlen;
1873 }
1874 ret = 0;
1875
1876 out:
1877 return ret;
1878 }
1879 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1880
1881 /***************************************************************
1882 * Kernel crypto API interface to register DRBG
1883 ***************************************************************/
1884
1885 /*
1886 * Look up the DRBG flags by given kernel crypto API cra_name
1887 * The code uses the drbg_cores definition to do this
1888 *
1889 * @cra_name kernel crypto API cra_name
1890 * @coreref reference to integer which is filled with the pointer to
1891 * the applicable core
1892 * @pr reference for setting prediction resistance
1893 *
1894 * return: flags
1895 */
drbg_convert_tfm_core(const char * cra_driver_name,int * coreref,bool * pr)1896 static inline void drbg_convert_tfm_core(const char *cra_driver_name,
1897 int *coreref, bool *pr)
1898 {
1899 int i = 0;
1900 size_t start = 0;
1901 int len = 0;
1902
1903 *pr = true;
1904 /* disassemble the names */
1905 if (!memcmp(cra_driver_name, "drbg_nopr_", 10)) {
1906 start = 10;
1907 *pr = false;
1908 } else if (!memcmp(cra_driver_name, "drbg_pr_", 8)) {
1909 start = 8;
1910 } else {
1911 return;
1912 }
1913
1914 /* remove the first part */
1915 len = strlen(cra_driver_name) - start;
1916 for (i = 0; ARRAY_SIZE(drbg_cores) > i; i++) {
1917 if (!memcmp(cra_driver_name + start, drbg_cores[i].cra_name,
1918 len)) {
1919 *coreref = i;
1920 return;
1921 }
1922 }
1923 }
1924
drbg_kcapi_init(struct crypto_tfm * tfm)1925 static int drbg_kcapi_init(struct crypto_tfm *tfm)
1926 {
1927 struct drbg_state *drbg = crypto_tfm_ctx(tfm);
1928
1929 mutex_init(&drbg->drbg_mutex);
1930
1931 return 0;
1932 }
1933
drbg_kcapi_cleanup(struct crypto_tfm * tfm)1934 static void drbg_kcapi_cleanup(struct crypto_tfm *tfm)
1935 {
1936 drbg_uninstantiate(crypto_tfm_ctx(tfm));
1937 }
1938
1939 /*
1940 * Generate random numbers invoked by the kernel crypto API:
1941 * The API of the kernel crypto API is extended as follows:
1942 *
1943 * src is additional input supplied to the RNG.
1944 * slen is the length of src.
1945 * dst is the output buffer where random data is to be stored.
1946 * dlen is the length of dst.
1947 */
drbg_kcapi_random(struct crypto_rng * tfm,const u8 * src,unsigned int slen,u8 * dst,unsigned int dlen)1948 static int drbg_kcapi_random(struct crypto_rng *tfm,
1949 const u8 *src, unsigned int slen,
1950 u8 *dst, unsigned int dlen)
1951 {
1952 struct drbg_state *drbg = crypto_rng_ctx(tfm);
1953 struct drbg_string *addtl = NULL;
1954 struct drbg_string string;
1955
1956 if (slen) {
1957 /* linked list variable is now local to allow modification */
1958 drbg_string_fill(&string, src, slen);
1959 addtl = &string;
1960 }
1961
1962 return drbg_generate_long(drbg, dst, dlen, addtl);
1963 }
1964
1965 /*
1966 * Seed the DRBG invoked by the kernel crypto API
1967 */
drbg_kcapi_seed(struct crypto_rng * tfm,const u8 * seed,unsigned int slen)1968 static int drbg_kcapi_seed(struct crypto_rng *tfm,
1969 const u8 *seed, unsigned int slen)
1970 {
1971 struct drbg_state *drbg = crypto_rng_ctx(tfm);
1972 struct crypto_tfm *tfm_base = crypto_rng_tfm(tfm);
1973 bool pr = false;
1974 struct drbg_string string;
1975 struct drbg_string *seed_string = NULL;
1976 int coreref = 0;
1977
1978 drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base), &coreref,
1979 &pr);
1980 if (0 < slen) {
1981 drbg_string_fill(&string, seed, slen);
1982 seed_string = &string;
1983 }
1984
1985 return drbg_instantiate(drbg, seed_string, coreref, pr);
1986 }
1987
1988 /***************************************************************
1989 * Kernel module: code to load the module
1990 ***************************************************************/
1991
1992 /*
1993 * Tests as defined in 11.3.2 in addition to the cipher tests: testing
1994 * of the error handling.
1995 *
1996 * Note: testing of failing seed source as defined in 11.3.2 is not applicable
1997 * as seed source of get_random_bytes does not fail.
1998 *
1999 * Note 2: There is no sensible way of testing the reseed counter
2000 * enforcement, so skip it.
2001 */
drbg_healthcheck_sanity(void)2002 static inline int __init drbg_healthcheck_sanity(void)
2003 {
2004 int len = 0;
2005 #define OUTBUFLEN 16
2006 unsigned char buf[OUTBUFLEN];
2007 struct drbg_state *drbg = NULL;
2008 int ret;
2009 int rc = -EFAULT;
2010 bool pr = false;
2011 int coreref = 0;
2012 struct drbg_string addtl;
2013 size_t max_addtllen, max_request_bytes;
2014
2015 /* only perform test in FIPS mode */
2016 if (!fips_enabled)
2017 return 0;
2018
2019 #ifdef CONFIG_CRYPTO_DRBG_CTR
2020 drbg_convert_tfm_core("drbg_nopr_ctr_aes128", &coreref, &pr);
2021 #elif defined CONFIG_CRYPTO_DRBG_HASH
2022 drbg_convert_tfm_core("drbg_nopr_sha256", &coreref, &pr);
2023 #else
2024 drbg_convert_tfm_core("drbg_nopr_hmac_sha256", &coreref, &pr);
2025 #endif
2026
2027 drbg = kzalloc(sizeof(struct drbg_state), GFP_KERNEL);
2028 if (!drbg)
2029 return -ENOMEM;
2030
2031 mutex_init(&drbg->drbg_mutex);
2032 drbg->core = &drbg_cores[coreref];
2033 drbg->reseed_threshold = drbg_max_requests(drbg);
2034
2035 /*
2036 * if the following tests fail, it is likely that there is a buffer
2037 * overflow as buf is much smaller than the requested or provided
2038 * string lengths -- in case the error handling does not succeed
2039 * we may get an OOPS. And we want to get an OOPS as this is a
2040 * grave bug.
2041 */
2042
2043 max_addtllen = drbg_max_addtl(drbg);
2044 max_request_bytes = drbg_max_request_bytes(drbg);
2045 drbg_string_fill(&addtl, buf, max_addtllen + 1);
2046 /* overflow addtllen with additonal info string */
2047 len = drbg_generate(drbg, buf, OUTBUFLEN, &addtl);
2048 BUG_ON(0 < len);
2049 /* overflow max_bits */
2050 len = drbg_generate(drbg, buf, (max_request_bytes + 1), NULL);
2051 BUG_ON(0 < len);
2052
2053 /* overflow max addtllen with personalization string */
2054 ret = drbg_seed(drbg, &addtl, false);
2055 BUG_ON(0 == ret);
2056 /* all tests passed */
2057 rc = 0;
2058
2059 pr_devel("DRBG: Sanity tests for failure code paths successfully "
2060 "completed\n");
2061
2062 kfree(drbg);
2063 return rc;
2064 }
2065
2066 static struct rng_alg drbg_algs[22];
2067
2068 /*
2069 * Fill the array drbg_algs used to register the different DRBGs
2070 * with the kernel crypto API. To fill the array, the information
2071 * from drbg_cores[] is used.
2072 */
drbg_fill_array(struct rng_alg * alg,const struct drbg_core * core,int pr)2073 static inline void __init drbg_fill_array(struct rng_alg *alg,
2074 const struct drbg_core *core, int pr)
2075 {
2076 int pos = 0;
2077 static int priority = 200;
2078
2079 memcpy(alg->base.cra_name, "stdrng", 6);
2080 if (pr) {
2081 memcpy(alg->base.cra_driver_name, "drbg_pr_", 8);
2082 pos = 8;
2083 } else {
2084 memcpy(alg->base.cra_driver_name, "drbg_nopr_", 10);
2085 pos = 10;
2086 }
2087 memcpy(alg->base.cra_driver_name + pos, core->cra_name,
2088 strlen(core->cra_name));
2089
2090 alg->base.cra_priority = priority;
2091 priority++;
2092 /*
2093 * If FIPS mode enabled, the selected DRBG shall have the
2094 * highest cra_priority over other stdrng instances to ensure
2095 * it is selected.
2096 */
2097 if (fips_enabled)
2098 alg->base.cra_priority += 200;
2099
2100 alg->base.cra_ctxsize = sizeof(struct drbg_state);
2101 alg->base.cra_module = THIS_MODULE;
2102 alg->base.cra_init = drbg_kcapi_init;
2103 alg->base.cra_exit = drbg_kcapi_cleanup;
2104 alg->generate = drbg_kcapi_random;
2105 alg->seed = drbg_kcapi_seed;
2106 alg->set_ent = drbg_kcapi_set_entropy;
2107 alg->seedsize = 0;
2108 }
2109
drbg_init(void)2110 static int __init drbg_init(void)
2111 {
2112 unsigned int i = 0; /* pointer to drbg_algs */
2113 unsigned int j = 0; /* pointer to drbg_cores */
2114 int ret;
2115
2116 ret = drbg_healthcheck_sanity();
2117 if (ret)
2118 return ret;
2119
2120 if (ARRAY_SIZE(drbg_cores) * 2 > ARRAY_SIZE(drbg_algs)) {
2121 pr_info("DRBG: Cannot register all DRBG types"
2122 "(slots needed: %zu, slots available: %zu)\n",
2123 ARRAY_SIZE(drbg_cores) * 2, ARRAY_SIZE(drbg_algs));
2124 return -EFAULT;
2125 }
2126
2127 /*
2128 * each DRBG definition can be used with PR and without PR, thus
2129 * we instantiate each DRBG in drbg_cores[] twice.
2130 *
2131 * As the order of placing them into the drbg_algs array matters
2132 * (the later DRBGs receive a higher cra_priority) we register the
2133 * prediction resistance DRBGs first as the should not be too
2134 * interesting.
2135 */
2136 for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
2137 drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 1);
2138 for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
2139 drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 0);
2140 return crypto_register_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
2141 }
2142
drbg_exit(void)2143 static void __exit drbg_exit(void)
2144 {
2145 crypto_unregister_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
2146 }
2147
2148 subsys_initcall(drbg_init);
2149 module_exit(drbg_exit);
2150 #ifndef CRYPTO_DRBG_HASH_STRING
2151 #define CRYPTO_DRBG_HASH_STRING ""
2152 #endif
2153 #ifndef CRYPTO_DRBG_HMAC_STRING
2154 #define CRYPTO_DRBG_HMAC_STRING ""
2155 #endif
2156 #ifndef CRYPTO_DRBG_CTR_STRING
2157 #define CRYPTO_DRBG_CTR_STRING ""
2158 #endif
2159 MODULE_LICENSE("GPL");
2160 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
2161 MODULE_DESCRIPTION("NIST SP800-90A Deterministic Random Bit Generator (DRBG) "
2162 "using following cores: "
2163 CRYPTO_DRBG_HASH_STRING
2164 CRYPTO_DRBG_HMAC_STRING
2165 CRYPTO_DRBG_CTR_STRING);
2166 MODULE_ALIAS_CRYPTO("stdrng");
2167 MODULE_IMPORT_NS(CRYPTO_INTERNAL);
2168
