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