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