2 * DRBG: Deterministic Random Bits Generator
3 * Based on NIST Recommended DRBG from NIST SP800-90A with the following
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
10 * Copyright Stephan Mueller <smueller@chronox.de>, 2014
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
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
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.)
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
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.
51 * Usage without any additional data
52 * ---------------------------------
53 * struct crypto_rng *drng;
57 * drng = crypto_alloc_rng(drng_name, 0, 0);
58 * err = crypto_rng_get_bytes(drng, &data, DATALEN);
59 * crypto_free_rng(drng);
62 * Usage with personalization string during initialization
63 * -------------------------------------------------------
64 * struct crypto_rng *drng;
67 * struct drbg_string pers;
68 * char personalization[11] = "some-string";
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);
79 * Usage with additional information string during random number request
80 * ---------------------------------------------------------------------
81 * struct crypto_rng *drng;
84 * char addtl_string[11] = "some-string";
85 * string drbg_string addtl;
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);
95 * Usage with personalization and additional information strings
96 * -------------------------------------------------------------
97 * Just mix both scenarios above.
100 #include <crypto/drbg.h>
102 /***************************************************************
103 * Backend cipher definitions available to DRBG
104 ***************************************************************/
107 * The order of the DRBG definitions here matter: every DRBG is registered
108 * as stdrng. Each DRBG receives an increasing cra_priority values the later
109 * they are defined in this array (see drbg_fill_array).
111 * HMAC DRBGs are favored over Hash DRBGs over CTR DRBGs, and
112 * the SHA256 / AES 256 over other ciphers. Thus, the favored
113 * DRBGs are the latest entries in this array.
115 static const struct drbg_core drbg_cores[] = {
116 #ifdef CONFIG_CRYPTO_DRBG_CTR
118 .flags = DRBG_CTR | DRBG_STRENGTH128,
119 .statelen = 32, /* 256 bits as defined in 10.2.1 */
120 .blocklen_bytes = 16,
121 .cra_name = "ctr_aes128",
122 .backend_cra_name = "aes",
124 .flags = DRBG_CTR | DRBG_STRENGTH192,
125 .statelen = 40, /* 320 bits as defined in 10.2.1 */
126 .blocklen_bytes = 16,
127 .cra_name = "ctr_aes192",
128 .backend_cra_name = "aes",
130 .flags = DRBG_CTR | DRBG_STRENGTH256,
131 .statelen = 48, /* 384 bits as defined in 10.2.1 */
132 .blocklen_bytes = 16,
133 .cra_name = "ctr_aes256",
134 .backend_cra_name = "aes",
136 #endif /* CONFIG_CRYPTO_DRBG_CTR */
137 #ifdef CONFIG_CRYPTO_DRBG_HASH
139 .flags = DRBG_HASH | DRBG_STRENGTH128,
140 .statelen = 55, /* 440 bits */
141 .blocklen_bytes = 20,
143 .backend_cra_name = "sha1",
145 .flags = DRBG_HASH | DRBG_STRENGTH256,
146 .statelen = 111, /* 888 bits */
147 .blocklen_bytes = 48,
148 .cra_name = "sha384",
149 .backend_cra_name = "sha384",
151 .flags = DRBG_HASH | DRBG_STRENGTH256,
152 .statelen = 111, /* 888 bits */
153 .blocklen_bytes = 64,
154 .cra_name = "sha512",
155 .backend_cra_name = "sha512",
157 .flags = DRBG_HASH | DRBG_STRENGTH256,
158 .statelen = 55, /* 440 bits */
159 .blocklen_bytes = 32,
160 .cra_name = "sha256",
161 .backend_cra_name = "sha256",
163 #endif /* CONFIG_CRYPTO_DRBG_HASH */
164 #ifdef CONFIG_CRYPTO_DRBG_HMAC
166 .flags = DRBG_HMAC | DRBG_STRENGTH128,
167 .statelen = 20, /* block length of cipher */
168 .blocklen_bytes = 20,
169 .cra_name = "hmac_sha1",
170 .backend_cra_name = "hmac(sha1)",
172 .flags = DRBG_HMAC | DRBG_STRENGTH256,
173 .statelen = 48, /* block length of cipher */
174 .blocklen_bytes = 48,
175 .cra_name = "hmac_sha384",
176 .backend_cra_name = "hmac(sha384)",
178 .flags = DRBG_HMAC | DRBG_STRENGTH256,
179 .statelen = 64, /* block length of cipher */
180 .blocklen_bytes = 64,
181 .cra_name = "hmac_sha512",
182 .backend_cra_name = "hmac(sha512)",
184 .flags = DRBG_HMAC | DRBG_STRENGTH256,
185 .statelen = 32, /* block length of cipher */
186 .blocklen_bytes = 32,
187 .cra_name = "hmac_sha256",
188 .backend_cra_name = "hmac(sha256)",
190 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
193 /******************************************************************
194 * Generic helper functions
195 ******************************************************************/
198 * Return strength of DRBG according to SP800-90A section 8.4
200 * @flags DRBG flags reference
202 * Return: normalized strength in *bytes* value or 32 as default
203 * to counter programming errors
205 static inline unsigned short drbg_sec_strength(drbg_flag_t flags)
207 switch (flags & DRBG_STRENGTH_MASK) {
208 case DRBG_STRENGTH128:
210 case DRBG_STRENGTH192:
212 case DRBG_STRENGTH256:
220 * FIPS 140-2 continuous self test
221 * The test is performed on the result of one round of the output
222 * function. Thus, the function implicitly knows the size of the
226 * @buf output buffer of random data to be checked
232 static bool drbg_fips_continuous_test(struct drbg_state *drbg,
233 const unsigned char *buf)
235 #ifdef CONFIG_CRYPTO_FIPS
237 /* skip test if we test the overall system */
240 /* only perform test in FIPS mode */
241 if (0 == fips_enabled)
243 if (!drbg->fips_primed) {
244 /* Priming of FIPS test */
245 memcpy(drbg->prev, buf, drbg_blocklen(drbg));
246 drbg->fips_primed = true;
247 /* return false due to priming, i.e. another round is needed */
250 ret = memcmp(drbg->prev, buf, drbg_blocklen(drbg));
252 panic("DRBG continuous self test failed\n");
253 memcpy(drbg->prev, buf, drbg_blocklen(drbg));
254 /* the test shall pass when the two compared values are not equal */
258 #endif /* CONFIG_CRYPTO_FIPS */
262 * Convert an integer into a byte representation of this integer.
263 * The byte representation is big-endian
265 * @val value to be converted
266 * @buf buffer holding the converted integer -- caller must ensure that
267 * buffer size is at least 32 bit
269 #if (defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR))
270 static inline void drbg_cpu_to_be32(__u32 val, unsigned char *buf)
275 struct s *conversion = (struct s *) buf;
277 conversion->conv = cpu_to_be32(val);
279 #endif /* defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR) */
281 /******************************************************************
282 * CTR DRBG callback functions
283 ******************************************************************/
285 #ifdef CONFIG_CRYPTO_DRBG_CTR
286 #define CRYPTO_DRBG_CTR_STRING "CTR "
287 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes256");
288 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes256");
289 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes192");
290 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes192");
291 MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes128");
292 MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes128");
294 static int drbg_kcapi_sym(struct drbg_state *drbg, const unsigned char *key,
295 unsigned char *outval, const struct drbg_string *in);
296 static int drbg_init_sym_kernel(struct drbg_state *drbg);
297 static int drbg_fini_sym_kernel(struct drbg_state *drbg);
299 /* BCC function for CTR DRBG as defined in 10.4.3 */
300 static int drbg_ctr_bcc(struct drbg_state *drbg,
301 unsigned char *out, const unsigned char *key,
302 struct list_head *in)
305 struct drbg_string *curr = NULL;
306 struct drbg_string data;
309 drbg_string_fill(&data, out, drbg_blocklen(drbg));
311 /* 10.4.3 step 2 / 4 */
312 list_for_each_entry(curr, in, list) {
313 const unsigned char *pos = curr->buf;
314 size_t len = curr->len;
315 /* 10.4.3 step 4.1 */
317 /* 10.4.3 step 4.2 */
318 if (drbg_blocklen(drbg) == cnt) {
320 ret = drbg_kcapi_sym(drbg, key, out, &data);
330 /* 10.4.3 step 4.2 for last block */
332 ret = drbg_kcapi_sym(drbg, key, out, &data);
338 * scratchpad usage: drbg_ctr_update is interlinked with drbg_ctr_df
339 * (and drbg_ctr_bcc, but this function does not need any temporary buffers),
340 * the scratchpad is used as follows:
343 * start: drbg->scratchpad
344 * length: drbg_statelen(drbg) + drbg_blocklen(drbg)
345 * note: the cipher writing into this variable works
346 * blocklen-wise. Now, when the statelen is not a multiple
347 * of blocklen, the generateion loop below "spills over"
348 * by at most blocklen. Thus, we need to give sufficient
351 * start: drbg->scratchpad +
352 * drbg_statelen(drbg) + drbg_blocklen(drbg)
353 * length: drbg_statelen(drbg)
357 * start: df_data + drbg_statelen(drbg)
358 * length: drbg_blocklen(drbg)
360 * start: pad + drbg_blocklen(drbg)
361 * length: drbg_blocklen(drbg)
363 * start: iv + drbg_blocklen(drbg)
364 * length: drbg_satelen(drbg) + drbg_blocklen(drbg)
365 * note: temp is the buffer that the BCC function operates
366 * on. BCC operates blockwise. drbg_statelen(drbg)
367 * is sufficient when the DRBG state length is a multiple
368 * of the block size. For AES192 (and maybe other ciphers)
369 * this is not correct and the length for temp is
370 * insufficient (yes, that also means for such ciphers,
371 * the final output of all BCC rounds are truncated).
372 * Therefore, add drbg_blocklen(drbg) to cover all
376 /* Derivation Function for CTR DRBG as defined in 10.4.2 */
377 static int drbg_ctr_df(struct drbg_state *drbg,
378 unsigned char *df_data, size_t bytes_to_return,
379 struct list_head *seedlist)
382 unsigned char L_N[8];
384 struct drbg_string S1, S2, S4, cipherin;
386 unsigned char *pad = df_data + drbg_statelen(drbg);
387 unsigned char *iv = pad + drbg_blocklen(drbg);
388 unsigned char *temp = iv + drbg_blocklen(drbg);
390 unsigned int templen = 0;
394 const unsigned char *K = (unsigned char *)
395 "\x00\x01\x02\x03\x04\x05\x06\x07"
396 "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
397 "\x10\x11\x12\x13\x14\x15\x16\x17"
398 "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f";
400 size_t generated_len = 0;
402 struct drbg_string *seed = NULL;
404 memset(pad, 0, drbg_blocklen(drbg));
405 memset(iv, 0, drbg_blocklen(drbg));
407 /* 10.4.2 step 1 is implicit as we work byte-wise */
410 if ((512/8) < bytes_to_return)
413 /* 10.4.2 step 2 -- calculate the entire length of all input data */
414 list_for_each_entry(seed, seedlist, list)
415 inputlen += seed->len;
416 drbg_cpu_to_be32(inputlen, &L_N[0]);
419 drbg_cpu_to_be32(bytes_to_return, &L_N[4]);
421 /* 10.4.2 step 5: length is L_N, input_string, one byte, padding */
422 padlen = (inputlen + sizeof(L_N) + 1) % (drbg_blocklen(drbg));
423 /* wrap the padlen appropriately */
425 padlen = drbg_blocklen(drbg) - padlen;
427 * pad / padlen contains the 0x80 byte and the following zero bytes.
428 * As the calculated padlen value only covers the number of zero
429 * bytes, this value has to be incremented by one for the 0x80 byte.
434 /* 10.4.2 step 4 -- first fill the linked list and then order it */
435 drbg_string_fill(&S1, iv, drbg_blocklen(drbg));
436 list_add_tail(&S1.list, &bcc_list);
437 drbg_string_fill(&S2, L_N, sizeof(L_N));
438 list_add_tail(&S2.list, &bcc_list);
439 list_splice_tail(seedlist, &bcc_list);
440 drbg_string_fill(&S4, pad, padlen);
441 list_add_tail(&S4.list, &bcc_list);
444 while (templen < (drbg_keylen(drbg) + (drbg_blocklen(drbg)))) {
446 * 10.4.2 step 9.1 - the padding is implicit as the buffer
447 * holds zeros after allocation -- even the increment of i
448 * is irrelevant as the increment remains within length of i
450 drbg_cpu_to_be32(i, iv);
451 /* 10.4.2 step 9.2 -- BCC and concatenation with temp */
452 ret = drbg_ctr_bcc(drbg, temp + templen, K, &bcc_list);
455 /* 10.4.2 step 9.3 */
457 templen += drbg_blocklen(drbg);
461 X = temp + (drbg_keylen(drbg));
462 drbg_string_fill(&cipherin, X, drbg_blocklen(drbg));
464 /* 10.4.2 step 12: overwriting of outval is implemented in next step */
467 while (generated_len < bytes_to_return) {
470 * 10.4.2 step 13.1: the truncation of the key length is
471 * implicit as the key is only drbg_blocklen in size based on
472 * the implementation of the cipher function callback
474 ret = drbg_kcapi_sym(drbg, temp, X, &cipherin);
477 blocklen = (drbg_blocklen(drbg) <
478 (bytes_to_return - generated_len)) ?
479 drbg_blocklen(drbg) :
480 (bytes_to_return - generated_len);
481 /* 10.4.2 step 13.2 and 14 */
482 memcpy(df_data + generated_len, X, blocklen);
483 generated_len += blocklen;
489 memset(iv, 0, drbg_blocklen(drbg));
490 memset(temp, 0, drbg_statelen(drbg));
491 memset(pad, 0, drbg_blocklen(drbg));
496 * update function of CTR DRBG as defined in 10.2.1.2
498 * The reseed variable has an enhanced meaning compared to the update
499 * functions of the other DRBGs as follows:
500 * 0 => initial seed from initialization
501 * 1 => reseed via drbg_seed
502 * 2 => first invocation from drbg_ctr_update when addtl is present. In
503 * this case, the df_data scratchpad is not deleted so that it is
504 * available for another calls to prevent calling the DF function
506 * 3 => second invocation from drbg_ctr_update. When the update function
507 * was called with addtl, the df_data memory already contains the
508 * DFed addtl information and we do not need to call DF again.
510 static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed,
514 /* 10.2.1.2 step 1 */
515 unsigned char *temp = drbg->scratchpad;
516 unsigned char *df_data = drbg->scratchpad + drbg_statelen(drbg) +
518 unsigned char *temp_p, *df_data_p; /* pointer to iterate over buffers */
519 unsigned int len = 0;
520 struct drbg_string cipherin;
523 memset(df_data, 0, drbg_statelen(drbg));
525 /* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */
527 ret = drbg_ctr_df(drbg, df_data, drbg_statelen(drbg), seed);
532 drbg_string_fill(&cipherin, drbg->V, drbg_blocklen(drbg));
534 * 10.2.1.3.2 steps 2 and 3 are already covered as the allocation
535 * zeroizes all memory during initialization
537 while (len < (drbg_statelen(drbg))) {
538 /* 10.2.1.2 step 2.1 */
539 crypto_inc(drbg->V, drbg_blocklen(drbg));
541 * 10.2.1.2 step 2.2 */
542 ret = drbg_kcapi_sym(drbg, drbg->C, temp + len, &cipherin);
545 /* 10.2.1.2 step 2.3 and 3 */
546 len += drbg_blocklen(drbg);
549 /* 10.2.1.2 step 4 */
552 for (len = 0; len < drbg_statelen(drbg); len++) {
553 *temp_p ^= *df_data_p;
554 df_data_p++; temp_p++;
557 /* 10.2.1.2 step 5 */
558 memcpy(drbg->C, temp, drbg_keylen(drbg));
559 /* 10.2.1.2 step 6 */
560 memcpy(drbg->V, temp + drbg_keylen(drbg), drbg_blocklen(drbg));
564 memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
566 memset(df_data, 0, drbg_statelen(drbg));
571 * scratchpad use: drbg_ctr_update is called independently from
572 * drbg_ctr_extract_bytes. Therefore, the scratchpad is reused
574 /* Generate function of CTR DRBG as defined in 10.2.1.5.2 */
575 static int drbg_ctr_generate(struct drbg_state *drbg,
576 unsigned char *buf, unsigned int buflen,
577 struct list_head *addtl)
581 struct drbg_string data;
583 /* 10.2.1.5.2 step 2 */
584 if (addtl && !list_empty(addtl)) {
585 ret = drbg_ctr_update(drbg, addtl, 2);
590 /* 10.2.1.5.2 step 4.1 */
591 crypto_inc(drbg->V, drbg_blocklen(drbg));
592 drbg_string_fill(&data, drbg->V, drbg_blocklen(drbg));
593 while (len < buflen) {
595 /* 10.2.1.5.2 step 4.2 */
596 ret = drbg_kcapi_sym(drbg, drbg->C, drbg->scratchpad, &data);
601 outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
602 drbg_blocklen(drbg) : (buflen - len);
603 if (!drbg_fips_continuous_test(drbg, drbg->scratchpad)) {
604 /* 10.2.1.5.2 step 6 */
605 crypto_inc(drbg->V, drbg_blocklen(drbg));
608 /* 10.2.1.5.2 step 4.3 */
609 memcpy(buf + len, drbg->scratchpad, outlen);
611 /* 10.2.1.5.2 step 6 */
613 crypto_inc(drbg->V, drbg_blocklen(drbg));
616 /* 10.2.1.5.2 step 6 */
617 ret = drbg_ctr_update(drbg, NULL, 3);
622 memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
626 static struct drbg_state_ops drbg_ctr_ops = {
627 .update = drbg_ctr_update,
628 .generate = drbg_ctr_generate,
629 .crypto_init = drbg_init_sym_kernel,
630 .crypto_fini = drbg_fini_sym_kernel,
632 #endif /* CONFIG_CRYPTO_DRBG_CTR */
634 /******************************************************************
635 * HMAC DRBG callback functions
636 ******************************************************************/
638 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
639 static int drbg_kcapi_hash(struct drbg_state *drbg, const unsigned char *key,
640 unsigned char *outval, const struct list_head *in);
641 static int drbg_init_hash_kernel(struct drbg_state *drbg);
642 static int drbg_fini_hash_kernel(struct drbg_state *drbg);
643 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
645 #ifdef CONFIG_CRYPTO_DRBG_HMAC
646 #define CRYPTO_DRBG_HMAC_STRING "HMAC "
647 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha512");
648 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha512");
649 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha384");
650 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha384");
651 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha256");
652 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha256");
653 MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha1");
654 MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha1");
656 /* update function of HMAC DRBG as defined in 10.1.2.2 */
657 static int drbg_hmac_update(struct drbg_state *drbg, struct list_head *seed,
662 struct drbg_string seed1, seed2, vdata;
664 LIST_HEAD(vdatalist);
667 /* 10.1.2.3 step 2 -- memset(0) of C is implicit with kzalloc */
668 memset(drbg->V, 1, drbg_statelen(drbg));
670 drbg_string_fill(&seed1, drbg->V, drbg_statelen(drbg));
671 list_add_tail(&seed1.list, &seedlist);
672 /* buffer of seed2 will be filled in for loop below with one byte */
673 drbg_string_fill(&seed2, NULL, 1);
674 list_add_tail(&seed2.list, &seedlist);
675 /* input data of seed is allowed to be NULL at this point */
677 list_splice_tail(seed, &seedlist);
679 drbg_string_fill(&vdata, drbg->V, drbg_statelen(drbg));
680 list_add_tail(&vdata.list, &vdatalist);
681 for (i = 2; 0 < i; i--) {
682 /* first round uses 0x0, second 0x1 */
683 unsigned char prefix = DRBG_PREFIX0;
685 prefix = DRBG_PREFIX1;
686 /* 10.1.2.2 step 1 and 4 -- concatenation and HMAC for key */
688 ret = drbg_kcapi_hash(drbg, drbg->C, drbg->C, &seedlist);
692 /* 10.1.2.2 step 2 and 5 -- HMAC for V */
693 ret = drbg_kcapi_hash(drbg, drbg->C, drbg->V, &vdatalist);
697 /* 10.1.2.2 step 3 */
705 /* generate function of HMAC DRBG as defined in 10.1.2.5 */
706 static int drbg_hmac_generate(struct drbg_state *drbg,
709 struct list_head *addtl)
713 struct drbg_string data;
716 /* 10.1.2.5 step 2 */
717 if (addtl && !list_empty(addtl)) {
718 ret = drbg_hmac_update(drbg, addtl, 1);
723 drbg_string_fill(&data, drbg->V, drbg_statelen(drbg));
724 list_add_tail(&data.list, &datalist);
725 while (len < buflen) {
726 unsigned int outlen = 0;
727 /* 10.1.2.5 step 4.1 */
728 ret = drbg_kcapi_hash(drbg, drbg->C, drbg->V, &datalist);
731 outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
732 drbg_blocklen(drbg) : (buflen - len);
733 if (!drbg_fips_continuous_test(drbg, drbg->V))
736 /* 10.1.2.5 step 4.2 */
737 memcpy(buf + len, drbg->V, outlen);
741 /* 10.1.2.5 step 6 */
742 if (addtl && !list_empty(addtl))
743 ret = drbg_hmac_update(drbg, addtl, 1);
745 ret = drbg_hmac_update(drbg, NULL, 1);
752 static struct drbg_state_ops drbg_hmac_ops = {
753 .update = drbg_hmac_update,
754 .generate = drbg_hmac_generate,
755 .crypto_init = drbg_init_hash_kernel,
756 .crypto_fini = drbg_fini_hash_kernel,
758 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
760 /******************************************************************
761 * Hash DRBG callback functions
762 ******************************************************************/
764 #ifdef CONFIG_CRYPTO_DRBG_HASH
765 #define CRYPTO_DRBG_HASH_STRING "HASH "
766 MODULE_ALIAS_CRYPTO("drbg_pr_sha512");
767 MODULE_ALIAS_CRYPTO("drbg_nopr_sha512");
768 MODULE_ALIAS_CRYPTO("drbg_pr_sha384");
769 MODULE_ALIAS_CRYPTO("drbg_nopr_sha384");
770 MODULE_ALIAS_CRYPTO("drbg_pr_sha256");
771 MODULE_ALIAS_CRYPTO("drbg_nopr_sha256");
772 MODULE_ALIAS_CRYPTO("drbg_pr_sha1");
773 MODULE_ALIAS_CRYPTO("drbg_nopr_sha1");
778 * @dst buffer to increment
781 static inline void drbg_add_buf(unsigned char *dst, size_t dstlen,
782 const unsigned char *add, size_t addlen)
784 /* implied: dstlen > addlen */
785 unsigned char *dstptr;
786 const unsigned char *addptr;
787 unsigned int remainder = 0;
790 dstptr = dst + (dstlen-1);
791 addptr = add + (addlen-1);
793 remainder += *dstptr + *addptr;
794 *dstptr = remainder & 0xff;
796 len--; dstptr--; addptr--;
798 len = dstlen - addlen;
799 while (len && remainder > 0) {
800 remainder = *dstptr + 1;
801 *dstptr = remainder & 0xff;
808 * scratchpad usage: as drbg_hash_update and drbg_hash_df are used
809 * interlinked, the scratchpad is used as follows:
811 * start: drbg->scratchpad
812 * length: drbg_statelen(drbg)
814 * start: drbg->scratchpad + drbg_statelen(drbg)
815 * length: drbg_blocklen(drbg)
817 * drbg_hash_process_addtl uses the scratchpad, but fully completes
818 * before either of the functions mentioned before are invoked. Therefore,
819 * drbg_hash_process_addtl does not need to be specifically considered.
822 /* Derivation Function for Hash DRBG as defined in 10.4.1 */
823 static int drbg_hash_df(struct drbg_state *drbg,
824 unsigned char *outval, size_t outlen,
825 struct list_head *entropylist)
829 unsigned char input[5];
830 unsigned char *tmp = drbg->scratchpad + drbg_statelen(drbg);
831 struct drbg_string data;
835 drbg_cpu_to_be32((outlen * 8), &input[1]);
837 /* 10.4.1 step 4.1 -- concatenation of data for input into hash */
838 drbg_string_fill(&data, input, 5);
839 list_add(&data.list, entropylist);
842 while (len < outlen) {
844 /* 10.4.1 step 4.1 */
845 ret = drbg_kcapi_hash(drbg, NULL, tmp, entropylist);
848 /* 10.4.1 step 4.2 */
850 blocklen = (drbg_blocklen(drbg) < (outlen - len)) ?
851 drbg_blocklen(drbg) : (outlen - len);
852 memcpy(outval + len, tmp, blocklen);
857 memset(tmp, 0, drbg_blocklen(drbg));
861 /* update function for Hash DRBG as defined in 10.1.1.2 / 10.1.1.3 */
862 static int drbg_hash_update(struct drbg_state *drbg, struct list_head *seed,
866 struct drbg_string data1, data2;
868 LIST_HEAD(datalist2);
869 unsigned char *V = drbg->scratchpad;
870 unsigned char prefix = DRBG_PREFIX1;
876 /* 10.1.1.3 step 1 */
877 memcpy(V, drbg->V, drbg_statelen(drbg));
878 drbg_string_fill(&data1, &prefix, 1);
879 list_add_tail(&data1.list, &datalist);
880 drbg_string_fill(&data2, V, drbg_statelen(drbg));
881 list_add_tail(&data2.list, &datalist);
883 list_splice_tail(seed, &datalist);
885 /* 10.1.1.2 / 10.1.1.3 step 2 and 3 */
886 ret = drbg_hash_df(drbg, drbg->V, drbg_statelen(drbg), &datalist);
890 /* 10.1.1.2 / 10.1.1.3 step 4 */
891 prefix = DRBG_PREFIX0;
892 drbg_string_fill(&data1, &prefix, 1);
893 list_add_tail(&data1.list, &datalist2);
894 drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
895 list_add_tail(&data2.list, &datalist2);
896 /* 10.1.1.2 / 10.1.1.3 step 4 */
897 ret = drbg_hash_df(drbg, drbg->C, drbg_statelen(drbg), &datalist2);
900 memset(drbg->scratchpad, 0, drbg_statelen(drbg));
904 /* processing of additional information string for Hash DRBG */
905 static int drbg_hash_process_addtl(struct drbg_state *drbg,
906 struct list_head *addtl)
909 struct drbg_string data1, data2;
911 unsigned char prefix = DRBG_PREFIX2;
913 /* 10.1.1.4 step 2 */
914 if (!addtl || list_empty(addtl))
917 /* 10.1.1.4 step 2a */
918 drbg_string_fill(&data1, &prefix, 1);
919 drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
920 list_add_tail(&data1.list, &datalist);
921 list_add_tail(&data2.list, &datalist);
922 list_splice_tail(addtl, &datalist);
923 ret = drbg_kcapi_hash(drbg, NULL, drbg->scratchpad, &datalist);
927 /* 10.1.1.4 step 2b */
928 drbg_add_buf(drbg->V, drbg_statelen(drbg),
929 drbg->scratchpad, drbg_blocklen(drbg));
932 memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
936 /* Hashgen defined in 10.1.1.4 */
937 static int drbg_hash_hashgen(struct drbg_state *drbg,
943 unsigned char *src = drbg->scratchpad;
944 unsigned char *dst = drbg->scratchpad + drbg_statelen(drbg);
945 struct drbg_string data;
948 /* 10.1.1.4 step hashgen 2 */
949 memcpy(src, drbg->V, drbg_statelen(drbg));
951 drbg_string_fill(&data, src, drbg_statelen(drbg));
952 list_add_tail(&data.list, &datalist);
953 while (len < buflen) {
954 unsigned int outlen = 0;
955 /* 10.1.1.4 step hashgen 4.1 */
956 ret = drbg_kcapi_hash(drbg, NULL, dst, &datalist);
961 outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
962 drbg_blocklen(drbg) : (buflen - len);
963 if (!drbg_fips_continuous_test(drbg, dst)) {
964 crypto_inc(src, drbg_statelen(drbg));
967 /* 10.1.1.4 step hashgen 4.2 */
968 memcpy(buf + len, dst, outlen);
970 /* 10.1.1.4 hashgen step 4.3 */
972 crypto_inc(src, drbg_statelen(drbg));
976 memset(drbg->scratchpad, 0,
977 (drbg_statelen(drbg) + drbg_blocklen(drbg)));
981 /* generate function for Hash DRBG as defined in 10.1.1.4 */
982 static int drbg_hash_generate(struct drbg_state *drbg,
983 unsigned char *buf, unsigned int buflen,
984 struct list_head *addtl)
989 unsigned char req[8];
992 unsigned char prefix = DRBG_PREFIX3;
993 struct drbg_string data1, data2;
996 /* 10.1.1.4 step 2 */
997 ret = drbg_hash_process_addtl(drbg, addtl);
1000 /* 10.1.1.4 step 3 */
1001 len = drbg_hash_hashgen(drbg, buf, buflen);
1003 /* this is the value H as documented in 10.1.1.4 */
1004 /* 10.1.1.4 step 4 */
1005 drbg_string_fill(&data1, &prefix, 1);
1006 list_add_tail(&data1.list, &datalist);
1007 drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
1008 list_add_tail(&data2.list, &datalist);
1009 ret = drbg_kcapi_hash(drbg, NULL, drbg->scratchpad, &datalist);
1015 /* 10.1.1.4 step 5 */
1016 drbg_add_buf(drbg->V, drbg_statelen(drbg),
1017 drbg->scratchpad, drbg_blocklen(drbg));
1018 drbg_add_buf(drbg->V, drbg_statelen(drbg),
1019 drbg->C, drbg_statelen(drbg));
1020 u.req_int = cpu_to_be64(drbg->reseed_ctr);
1021 drbg_add_buf(drbg->V, drbg_statelen(drbg), u.req, 8);
1024 memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
1029 * scratchpad usage: as update and generate are used isolated, both
1030 * can use the scratchpad
1032 static struct drbg_state_ops drbg_hash_ops = {
1033 .update = drbg_hash_update,
1034 .generate = drbg_hash_generate,
1035 .crypto_init = drbg_init_hash_kernel,
1036 .crypto_fini = drbg_fini_hash_kernel,
1038 #endif /* CONFIG_CRYPTO_DRBG_HASH */
1040 /******************************************************************
1041 * Functions common for DRBG implementations
1042 ******************************************************************/
1045 * Seeding or reseeding of the DRBG
1047 * @drbg: DRBG state struct
1048 * @pers: personalization / additional information buffer
1049 * @reseed: 0 for initial seed process, 1 for reseeding
1053 * error value otherwise
1055 static int drbg_seed(struct drbg_state *drbg, struct drbg_string *pers,
1059 unsigned char *entropy = NULL;
1060 size_t entropylen = 0;
1061 struct drbg_string data1;
1062 LIST_HEAD(seedlist);
1064 /* 9.1 / 9.2 / 9.3.1 step 3 */
1065 if (pers && pers->len > (drbg_max_addtl(drbg))) {
1066 pr_devel("DRBG: personalization string too long %zu\n",
1071 if (drbg->test_data && drbg->test_data->testentropy) {
1072 drbg_string_fill(&data1, drbg->test_data->testentropy->buf,
1073 drbg->test_data->testentropy->len);
1074 pr_devel("DRBG: using test entropy\n");
1077 * Gather entropy equal to the security strength of the DRBG.
1078 * With a derivation function, a nonce is required in addition
1079 * to the entropy. A nonce must be at least 1/2 of the security
1080 * strength of the DRBG in size. Thus, entropy * nonce is 3/2
1081 * of the strength. The consideration of a nonce is only
1082 * applicable during initial seeding.
1084 entropylen = drbg_sec_strength(drbg->core->flags);
1088 entropylen = ((entropylen + 1) / 2) * 3;
1089 pr_devel("DRBG: (re)seeding with %zu bytes of entropy\n",
1091 entropy = kzalloc(entropylen, GFP_KERNEL);
1094 get_random_bytes(entropy, entropylen);
1095 drbg_string_fill(&data1, entropy, entropylen);
1097 list_add_tail(&data1.list, &seedlist);
1100 * concatenation of entropy with personalization str / addtl input)
1101 * the variable pers is directly handed in by the caller, so check its
1102 * contents whether it is appropriate
1104 if (pers && pers->buf && 0 < pers->len) {
1105 list_add_tail(&pers->list, &seedlist);
1106 pr_devel("DRBG: using personalization string\n");
1110 memset(drbg->V, 0, drbg_statelen(drbg));
1111 memset(drbg->C, 0, drbg_statelen(drbg));
1114 ret = drbg->d_ops->update(drbg, &seedlist, reseed);
1118 drbg->seeded = true;
1119 /* 10.1.1.2 / 10.1.1.3 step 5 */
1120 drbg->reseed_ctr = 1;
1127 /* Free all substructures in a DRBG state without the DRBG state structure */
1128 static inline void drbg_dealloc_state(struct drbg_state *drbg)
1136 kzfree(drbg->scratchpad);
1137 drbg->scratchpad = NULL;
1138 drbg->reseed_ctr = 0;
1139 #ifdef CONFIG_CRYPTO_FIPS
1142 drbg->fips_primed = false;
1147 * Allocate all sub-structures for a DRBG state.
1148 * The DRBG state structure must already be allocated.
1150 static inline int drbg_alloc_state(struct drbg_state *drbg)
1153 unsigned int sb_size = 0;
1155 drbg->V = kmalloc(drbg_statelen(drbg), GFP_KERNEL);
1158 drbg->C = kmalloc(drbg_statelen(drbg), GFP_KERNEL);
1161 #ifdef CONFIG_CRYPTO_FIPS
1162 drbg->prev = kmalloc(drbg_blocklen(drbg), GFP_KERNEL);
1165 drbg->fips_primed = false;
1167 /* scratchpad is only generated for CTR and Hash */
1168 if (drbg->core->flags & DRBG_HMAC)
1170 else if (drbg->core->flags & DRBG_CTR)
1171 sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg) + /* temp */
1172 drbg_statelen(drbg) + /* df_data */
1173 drbg_blocklen(drbg) + /* pad */
1174 drbg_blocklen(drbg) + /* iv */
1175 drbg_statelen(drbg) + drbg_blocklen(drbg); /* temp */
1177 sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg);
1180 drbg->scratchpad = kzalloc(sb_size, GFP_KERNEL);
1181 if (!drbg->scratchpad)
1184 spin_lock_init(&drbg->drbg_lock);
1188 drbg_dealloc_state(drbg);
1193 * Strategy to avoid holding long term locks: generate a shadow copy of DRBG
1194 * and perform all operations on this shadow copy. After finishing, restore
1195 * the updated state of the shadow copy into original drbg state. This way,
1196 * only the read and write operations of the original drbg state must be
1199 static inline void drbg_copy_drbg(struct drbg_state *src,
1200 struct drbg_state *dst)
1204 memcpy(dst->V, src->V, drbg_statelen(src));
1205 memcpy(dst->C, src->C, drbg_statelen(src));
1206 dst->reseed_ctr = src->reseed_ctr;
1207 dst->seeded = src->seeded;
1209 #ifdef CONFIG_CRYPTO_FIPS
1210 dst->fips_primed = src->fips_primed;
1211 memcpy(dst->prev, src->prev, drbg_blocklen(src));
1215 * scratchpad is initialized drbg_alloc_state;
1216 * priv_data is initialized with call to crypto_init;
1217 * d_ops and core are set outside, as these parameters are const;
1218 * test_data is set outside to prevent it being copied back.
1222 static int drbg_make_shadow(struct drbg_state *drbg, struct drbg_state **shadow)
1225 struct drbg_state *tmp = NULL;
1227 tmp = kzalloc(sizeof(struct drbg_state), GFP_KERNEL);
1231 /* read-only data as they are defined as const, no lock needed */
1232 tmp->core = drbg->core;
1233 tmp->d_ops = drbg->d_ops;
1235 ret = drbg_alloc_state(tmp);
1239 spin_lock_bh(&drbg->drbg_lock);
1240 drbg_copy_drbg(drbg, tmp);
1241 /* only make a link to the test buffer, as we only read that data */
1242 tmp->test_data = drbg->test_data;
1243 spin_unlock_bh(&drbg->drbg_lock);
1252 static void drbg_restore_shadow(struct drbg_state *drbg,
1253 struct drbg_state **shadow)
1255 struct drbg_state *tmp = *shadow;
1257 spin_lock_bh(&drbg->drbg_lock);
1258 drbg_copy_drbg(tmp, drbg);
1259 spin_unlock_bh(&drbg->drbg_lock);
1260 drbg_dealloc_state(tmp);
1265 /*************************************************************************
1266 * DRBG interface functions
1267 *************************************************************************/
1270 * DRBG generate function as required by SP800-90A - this function
1271 * generates random numbers
1273 * @drbg DRBG state handle
1274 * @buf Buffer where to store the random numbers -- the buffer must already
1275 * be pre-allocated by caller
1276 * @buflen Length of output buffer - this value defines the number of random
1277 * bytes pulled from DRBG
1278 * @addtl Additional input that is mixed into state, may be NULL -- note
1279 * the entropy is pulled by the DRBG internally unconditionally
1280 * as defined in SP800-90A. The additional input is mixed into
1281 * the state in addition to the pulled entropy.
1283 * return: 0 when all bytes are generated; < 0 in case of an error
1285 static int drbg_generate(struct drbg_state *drbg,
1286 unsigned char *buf, unsigned int buflen,
1287 struct drbg_string *addtl)
1290 struct drbg_state *shadow = NULL;
1291 LIST_HEAD(addtllist);
1292 struct drbg_string timestamp;
1295 unsigned char char_cycles[sizeof(cycles_t)];
1298 if (0 == buflen || !buf) {
1299 pr_devel("DRBG: no output buffer provided\n");
1302 if (addtl && NULL == addtl->buf && 0 < addtl->len) {
1303 pr_devel("DRBG: wrong format of additional information\n");
1307 len = drbg_make_shadow(drbg, &shadow);
1309 pr_devel("DRBG: shadow copy cannot be generated\n");
1315 if (buflen > (drbg_max_request_bytes(shadow))) {
1316 pr_devel("DRBG: requested random numbers too large %u\n",
1321 /* 9.3.1 step 3 is implicit with the chosen DRBG */
1324 if (addtl && addtl->len > (drbg_max_addtl(shadow))) {
1325 pr_devel("DRBG: additional information string too long %zu\n",
1329 /* 9.3.1 step 5 is implicit with the chosen DRBG */
1332 * 9.3.1 step 6 and 9 supplemented by 9.3.2 step c is implemented
1333 * here. The spec is a bit convoluted here, we make it simpler.
1335 if ((drbg_max_requests(shadow)) < shadow->reseed_ctr)
1336 shadow->seeded = false;
1338 /* allocate cipher handle */
1339 len = shadow->d_ops->crypto_init(shadow);
1343 if (shadow->pr || !shadow->seeded) {
1344 pr_devel("DRBG: reseeding before generation (prediction "
1345 "resistance: %s, state %s)\n",
1346 drbg->pr ? "true" : "false",
1347 drbg->seeded ? "seeded" : "unseeded");
1348 /* 9.3.1 steps 7.1 through 7.3 */
1349 len = drbg_seed(shadow, addtl, true);
1352 /* 9.3.1 step 7.4 */
1357 * Mix the time stamp into the DRBG state if the DRBG is not in
1358 * test mode. If there are two callers invoking the DRBG at the same
1359 * time, i.e. before the first caller merges its shadow state back,
1360 * both callers would obtain the same random number stream without
1361 * changing the state here.
1363 if (!drbg->test_data) {
1364 now.cycles = random_get_entropy();
1365 drbg_string_fill(×tamp, now.char_cycles, sizeof(cycles_t));
1366 list_add_tail(×tamp.list, &addtllist);
1368 if (addtl && 0 < addtl->len)
1369 list_add_tail(&addtl->list, &addtllist);
1370 /* 9.3.1 step 8 and 10 */
1371 len = shadow->d_ops->generate(shadow, buf, buflen, &addtllist);
1373 /* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */
1374 shadow->reseed_ctr++;
1379 * Section 11.3.3 requires to re-perform self tests after some
1380 * generated random numbers. The chosen value after which self
1381 * test is performed is arbitrary, but it should be reasonable.
1382 * However, we do not perform the self tests because of the following
1383 * reasons: it is mathematically impossible that the initial self tests
1384 * were successfully and the following are not. If the initial would
1385 * pass and the following would not, the kernel integrity is violated.
1386 * In this case, the entire kernel operation is questionable and it
1387 * is unlikely that the integrity violation only affects the
1388 * correct operation of the DRBG.
1390 * Albeit the following code is commented out, it is provided in
1391 * case somebody has a need to implement the test of 11.3.3.
1394 if (shadow->reseed_ctr && !(shadow->reseed_ctr % 4096)) {
1396 pr_devel("DRBG: start to perform self test\n");
1397 if (drbg->core->flags & DRBG_HMAC)
1398 err = alg_test("drbg_pr_hmac_sha256",
1399 "drbg_pr_hmac_sha256", 0, 0);
1400 else if (drbg->core->flags & DRBG_CTR)
1401 err = alg_test("drbg_pr_ctr_aes128",
1402 "drbg_pr_ctr_aes128", 0, 0);
1404 err = alg_test("drbg_pr_sha256",
1405 "drbg_pr_sha256", 0, 0);
1407 pr_err("DRBG: periodical self test failed\n");
1409 * uninstantiate implies that from now on, only errors
1410 * are returned when reusing this DRBG cipher handle
1412 drbg_uninstantiate(drbg);
1413 drbg_dealloc_state(shadow);
1417 pr_devel("DRBG: self test successful\n");
1423 * All operations were successful, return 0 as mandated by
1424 * the kernel crypto API interface.
1428 shadow->d_ops->crypto_fini(shadow);
1429 drbg_restore_shadow(drbg, &shadow);
1434 * Wrapper around drbg_generate which can pull arbitrary long strings
1435 * from the DRBG without hitting the maximum request limitation.
1437 * Parameters: see drbg_generate
1438 * Return codes: see drbg_generate -- if one drbg_generate request fails,
1439 * the entire drbg_generate_long request fails
1441 static int drbg_generate_long(struct drbg_state *drbg,
1442 unsigned char *buf, unsigned int buflen,
1443 struct drbg_string *addtl)
1446 unsigned int slice = 0;
1449 unsigned int chunk = 0;
1450 slice = ((buflen - len) / drbg_max_request_bytes(drbg));
1451 chunk = slice ? drbg_max_request_bytes(drbg) : (buflen - len);
1452 tmplen = drbg_generate(drbg, buf + len, chunk, addtl);
1456 } while (slice > 0 && (len < buflen));
1461 * DRBG instantiation function as required by SP800-90A - this function
1462 * sets up the DRBG handle, performs the initial seeding and all sanity
1463 * checks required by SP800-90A
1465 * @drbg memory of state -- if NULL, new memory is allocated
1466 * @pers Personalization string that is mixed into state, may be NULL -- note
1467 * the entropy is pulled by the DRBG internally unconditionally
1468 * as defined in SP800-90A. The additional input is mixed into
1469 * the state in addition to the pulled entropy.
1470 * @coreref reference to core
1471 * @pr prediction resistance enabled
1475 * error value otherwise
1477 static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers,
1478 int coreref, bool pr)
1482 pr_devel("DRBG: Initializing DRBG core %d with prediction resistance "
1483 "%s\n", coreref, pr ? "enabled" : "disabled");
1484 drbg->core = &drbg_cores[coreref];
1486 drbg->seeded = false;
1487 switch (drbg->core->flags & DRBG_TYPE_MASK) {
1488 #ifdef CONFIG_CRYPTO_DRBG_HMAC
1490 drbg->d_ops = &drbg_hmac_ops;
1492 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
1493 #ifdef CONFIG_CRYPTO_DRBG_HASH
1495 drbg->d_ops = &drbg_hash_ops;
1497 #endif /* CONFIG_CRYPTO_DRBG_HASH */
1498 #ifdef CONFIG_CRYPTO_DRBG_CTR
1500 drbg->d_ops = &drbg_ctr_ops;
1502 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1507 /* 9.1 step 1 is implicit with the selected DRBG type */
1510 * 9.1 step 2 is implicit as caller can select prediction resistance
1511 * and the flag is copied into drbg->flags --
1512 * all DRBG types support prediction resistance
1515 /* 9.1 step 4 is implicit in drbg_sec_strength */
1517 ret = drbg_alloc_state(drbg);
1522 if (drbg->d_ops->crypto_init(drbg))
1524 ret = drbg_seed(drbg, pers, false);
1525 drbg->d_ops->crypto_fini(drbg);
1532 drbg_dealloc_state(drbg);
1537 * DRBG uninstantiate function as required by SP800-90A - this function
1538 * frees all buffers and the DRBG handle
1540 * @drbg DRBG state handle
1545 static int drbg_uninstantiate(struct drbg_state *drbg)
1547 spin_lock_bh(&drbg->drbg_lock);
1548 drbg_dealloc_state(drbg);
1549 /* no scrubbing of test_data -- this shall survive an uninstantiate */
1550 spin_unlock_bh(&drbg->drbg_lock);
1555 * Helper function for setting the test data in the DRBG
1557 * @drbg DRBG state handle
1558 * @test_data test data to sets
1560 static inline void drbg_set_testdata(struct drbg_state *drbg,
1561 struct drbg_test_data *test_data)
1563 if (!test_data || !test_data->testentropy)
1565 spin_lock_bh(&drbg->drbg_lock);
1566 drbg->test_data = test_data;
1567 spin_unlock_bh(&drbg->drbg_lock);
1570 /***************************************************************
1571 * Kernel crypto API cipher invocations requested by DRBG
1572 ***************************************************************/
1574 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
1576 struct shash_desc shash;
1580 static int drbg_init_hash_kernel(struct drbg_state *drbg)
1582 struct sdesc *sdesc;
1583 struct crypto_shash *tfm;
1585 tfm = crypto_alloc_shash(drbg->core->backend_cra_name, 0, 0);
1587 pr_info("DRBG: could not allocate digest TFM handle\n");
1588 return PTR_ERR(tfm);
1590 BUG_ON(drbg_blocklen(drbg) != crypto_shash_digestsize(tfm));
1591 sdesc = kzalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm),
1594 crypto_free_shash(tfm);
1598 sdesc->shash.tfm = tfm;
1599 sdesc->shash.flags = 0;
1600 drbg->priv_data = sdesc;
1604 static int drbg_fini_hash_kernel(struct drbg_state *drbg)
1606 struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1608 crypto_free_shash(sdesc->shash.tfm);
1611 drbg->priv_data = NULL;
1615 static int drbg_kcapi_hash(struct drbg_state *drbg, const unsigned char *key,
1616 unsigned char *outval, const struct list_head *in)
1618 struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
1619 struct drbg_string *input = NULL;
1622 crypto_shash_setkey(sdesc->shash.tfm, key, drbg_statelen(drbg));
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);
1628 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
1630 #ifdef CONFIG_CRYPTO_DRBG_CTR
1631 static int drbg_init_sym_kernel(struct drbg_state *drbg)
1634 struct crypto_cipher *tfm;
1636 tfm = crypto_alloc_cipher(drbg->core->backend_cra_name, 0, 0);
1638 pr_info("DRBG: could not allocate cipher TFM handle\n");
1639 return PTR_ERR(tfm);
1641 BUG_ON(drbg_blocklen(drbg) != crypto_cipher_blocksize(tfm));
1642 drbg->priv_data = tfm;
1646 static int drbg_fini_sym_kernel(struct drbg_state *drbg)
1648 struct crypto_cipher *tfm =
1649 (struct crypto_cipher *)drbg->priv_data;
1651 crypto_free_cipher(tfm);
1652 drbg->priv_data = NULL;
1656 static int drbg_kcapi_sym(struct drbg_state *drbg, const unsigned char *key,
1657 unsigned char *outval, const struct drbg_string *in)
1659 struct crypto_cipher *tfm =
1660 (struct crypto_cipher *)drbg->priv_data;
1662 crypto_cipher_setkey(tfm, key, (drbg_keylen(drbg)));
1663 /* there is only component in *in */
1664 BUG_ON(in->len < drbg_blocklen(drbg));
1665 crypto_cipher_encrypt_one(tfm, outval, in->buf);
1668 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1670 /***************************************************************
1671 * Kernel crypto API interface to register DRBG
1672 ***************************************************************/
1675 * Look up the DRBG flags by given kernel crypto API cra_name
1676 * The code uses the drbg_cores definition to do this
1678 * @cra_name kernel crypto API cra_name
1679 * @coreref reference to integer which is filled with the pointer to
1680 * the applicable core
1681 * @pr reference for setting prediction resistance
1685 static inline void drbg_convert_tfm_core(const char *cra_driver_name,
1686 int *coreref, bool *pr)
1693 /* disassemble the names */
1694 if (!memcmp(cra_driver_name, "drbg_nopr_", 10)) {
1697 } else if (!memcmp(cra_driver_name, "drbg_pr_", 8)) {
1703 /* remove the first part */
1704 len = strlen(cra_driver_name) - start;
1705 for (i = 0; ARRAY_SIZE(drbg_cores) > i; i++) {
1706 if (!memcmp(cra_driver_name + start, drbg_cores[i].cra_name,
1714 static int drbg_kcapi_init(struct crypto_tfm *tfm)
1716 struct drbg_state *drbg = crypto_tfm_ctx(tfm);
1720 drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm), &coreref, &pr);
1722 * when personalization string is needed, the caller must call reset
1723 * and provide the personalization string as seed information
1725 return drbg_instantiate(drbg, NULL, coreref, pr);
1728 static void drbg_kcapi_cleanup(struct crypto_tfm *tfm)
1730 drbg_uninstantiate(crypto_tfm_ctx(tfm));
1734 * Generate random numbers invoked by the kernel crypto API:
1735 * The API of the kernel crypto API is extended as follows:
1737 * If dlen is larger than zero, rdata is interpreted as the output buffer
1738 * where random data is to be stored.
1740 * If dlen is zero, rdata is interpreted as a pointer to a struct drbg_gen
1741 * which holds the additional information string that is used for the
1742 * DRBG generation process. The output buffer that is to be used to store
1743 * data is also pointed to by struct drbg_gen.
1745 static int drbg_kcapi_random(struct crypto_rng *tfm, u8 *rdata,
1748 struct drbg_state *drbg = crypto_rng_ctx(tfm);
1750 return drbg_generate_long(drbg, rdata, dlen, NULL);
1752 struct drbg_gen *data = (struct drbg_gen *)rdata;
1753 struct drbg_string addtl;
1754 /* catch NULL pointer */
1757 drbg_set_testdata(drbg, data->test_data);
1758 /* linked list variable is now local to allow modification */
1759 drbg_string_fill(&addtl, data->addtl->buf, data->addtl->len);
1760 return drbg_generate_long(drbg, data->outbuf, data->outlen,
1766 * Reset the DRBG invoked by the kernel crypto API
1767 * The reset implies a full re-initialization of the DRBG. Similar to the
1768 * generate function of drbg_kcapi_random, this function extends the
1769 * kernel crypto API interface with struct drbg_gen
1771 static int drbg_kcapi_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen)
1773 struct drbg_state *drbg = crypto_rng_ctx(tfm);
1774 struct crypto_tfm *tfm_base = crypto_rng_tfm(tfm);
1776 struct drbg_string seed_string;
1779 drbg_uninstantiate(drbg);
1780 drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base), &coreref,
1783 drbg_string_fill(&seed_string, seed, slen);
1784 return drbg_instantiate(drbg, &seed_string, coreref, pr);
1786 struct drbg_gen *data = (struct drbg_gen *)seed;
1787 /* allow invocation of API call with NULL, 0 */
1789 return drbg_instantiate(drbg, NULL, coreref, pr);
1790 drbg_set_testdata(drbg, data->test_data);
1791 /* linked list variable is now local to allow modification */
1792 drbg_string_fill(&seed_string, data->addtl->buf,
1794 return drbg_instantiate(drbg, &seed_string, coreref, pr);
1798 /***************************************************************
1799 * Kernel module: code to load the module
1800 ***************************************************************/
1803 * Tests as defined in 11.3.2 in addition to the cipher tests: testing
1804 * of the error handling.
1806 * Note: testing of failing seed source as defined in 11.3.2 is not applicable
1807 * as seed source of get_random_bytes does not fail.
1809 * Note 2: There is no sensible way of testing the reseed counter
1810 * enforcement, so skip it.
1812 static inline int __init drbg_healthcheck_sanity(void)
1814 #ifdef CONFIG_CRYPTO_FIPS
1816 #define OUTBUFLEN 16
1817 unsigned char buf[OUTBUFLEN];
1818 struct drbg_state *drbg = NULL;
1823 struct drbg_string addtl;
1824 size_t max_addtllen, max_request_bytes;
1826 /* only perform test in FIPS mode */
1830 #ifdef CONFIG_CRYPTO_DRBG_CTR
1831 drbg_convert_tfm_core("drbg_nopr_ctr_aes128", &coreref, &pr);
1832 #elif defined CONFIG_CRYPTO_DRBG_HASH
1833 drbg_convert_tfm_core("drbg_nopr_sha256", &coreref, &pr);
1835 drbg_convert_tfm_core("drbg_nopr_hmac_sha256", &coreref, &pr);
1838 drbg = kzalloc(sizeof(struct drbg_state), GFP_KERNEL);
1843 * if the following tests fail, it is likely that there is a buffer
1844 * overflow as buf is much smaller than the requested or provided
1845 * string lengths -- in case the error handling does not succeed
1846 * we may get an OOPS. And we want to get an OOPS as this is a
1850 /* get a valid instance of DRBG for following tests */
1851 ret = drbg_instantiate(drbg, NULL, coreref, pr);
1856 max_addtllen = drbg_max_addtl(drbg);
1857 max_request_bytes = drbg_max_request_bytes(drbg);
1858 drbg_string_fill(&addtl, buf, max_addtllen + 1);
1859 /* overflow addtllen with additonal info string */
1860 len = drbg_generate(drbg, buf, OUTBUFLEN, &addtl);
1862 /* overflow max_bits */
1863 len = drbg_generate(drbg, buf, (max_request_bytes + 1), NULL);
1865 drbg_uninstantiate(drbg);
1867 /* overflow max addtllen with personalization string */
1868 ret = drbg_instantiate(drbg, &addtl, coreref, pr);
1870 /* all tests passed */
1873 pr_devel("DRBG: Sanity tests for failure code paths successfully "
1876 drbg_uninstantiate(drbg);
1880 #else /* CONFIG_CRYPTO_FIPS */
1882 #endif /* CONFIG_CRYPTO_FIPS */
1885 static struct crypto_alg drbg_algs[22];
1888 * Fill the array drbg_algs used to register the different DRBGs
1889 * with the kernel crypto API. To fill the array, the information
1890 * from drbg_cores[] is used.
1892 static inline void __init drbg_fill_array(struct crypto_alg *alg,
1893 const struct drbg_core *core, int pr)
1896 static int priority = 100;
1898 memset(alg, 0, sizeof(struct crypto_alg));
1899 memcpy(alg->cra_name, "stdrng", 6);
1901 memcpy(alg->cra_driver_name, "drbg_pr_", 8);
1904 memcpy(alg->cra_driver_name, "drbg_nopr_", 10);
1907 memcpy(alg->cra_driver_name + pos, core->cra_name,
1908 strlen(core->cra_name));
1910 alg->cra_priority = priority;
1913 * If FIPS mode enabled, the selected DRBG shall have the
1914 * highest cra_priority over other stdrng instances to ensure
1918 alg->cra_priority += 200;
1920 alg->cra_flags = CRYPTO_ALG_TYPE_RNG;
1921 alg->cra_ctxsize = sizeof(struct drbg_state);
1922 alg->cra_type = &crypto_rng_type;
1923 alg->cra_module = THIS_MODULE;
1924 alg->cra_init = drbg_kcapi_init;
1925 alg->cra_exit = drbg_kcapi_cleanup;
1926 alg->cra_u.rng.rng_make_random = drbg_kcapi_random;
1927 alg->cra_u.rng.rng_reset = drbg_kcapi_reset;
1928 alg->cra_u.rng.seedsize = 0;
1931 static int __init drbg_init(void)
1933 unsigned int i = 0; /* pointer to drbg_algs */
1934 unsigned int j = 0; /* pointer to drbg_cores */
1937 ret = drbg_healthcheck_sanity();
1941 if (ARRAY_SIZE(drbg_cores) * 2 > ARRAY_SIZE(drbg_algs)) {
1942 pr_info("DRBG: Cannot register all DRBG types"
1943 "(slots needed: %zu, slots available: %zu)\n",
1944 ARRAY_SIZE(drbg_cores) * 2, ARRAY_SIZE(drbg_algs));
1949 * each DRBG definition can be used with PR and without PR, thus
1950 * we instantiate each DRBG in drbg_cores[] twice.
1952 * As the order of placing them into the drbg_algs array matters
1953 * (the later DRBGs receive a higher cra_priority) we register the
1954 * prediction resistance DRBGs first as the should not be too
1957 for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
1958 drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 1);
1959 for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
1960 drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 0);
1961 return crypto_register_algs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
1964 static void __exit drbg_exit(void)
1966 crypto_unregister_algs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));
1969 module_init(drbg_init);
1970 module_exit(drbg_exit);
1971 #ifndef CRYPTO_DRBG_HASH_STRING
1972 #define CRYPTO_DRBG_HASH_STRING ""
1974 #ifndef CRYPTO_DRBG_HMAC_STRING
1975 #define CRYPTO_DRBG_HMAC_STRING ""
1977 #ifndef CRYPTO_DRBG_CTR_STRING
1978 #define CRYPTO_DRBG_CTR_STRING ""
1980 MODULE_LICENSE("GPL");
1981 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
1982 MODULE_DESCRIPTION("NIST SP800-90A Deterministic Random Bit Generator (DRBG) "
1983 "using following cores: "
1984 CRYPTO_DRBG_HASH_STRING
1985 CRYPTO_DRBG_HMAC_STRING
1986 CRYPTO_DRBG_CTR_STRING);