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 */
123 .blocklen_bytes
= 16,
124 .cra_name
= "ctr_aes128",
125 .backend_cra_name
= "ecb(aes)",
127 .flags
= DRBG_CTR
| DRBG_STRENGTH192
,
128 .statelen
= 40, /* 320 bits as defined in 10.2.1 */
132 .blocklen_bytes
= 16,
133 .cra_name
= "ctr_aes192",
134 .backend_cra_name
= "ecb(aes)",
136 .flags
= DRBG_CTR
| DRBG_STRENGTH256
,
137 .statelen
= 48, /* 384 bits as defined in 10.2.1 */
141 .blocklen_bytes
= 16,
142 .cra_name
= "ctr_aes256",
143 .backend_cra_name
= "ecb(aes)",
145 #endif /* CONFIG_CRYPTO_DRBG_CTR */
146 #ifdef CONFIG_CRYPTO_DRBG_HASH
148 .flags
= DRBG_HASH
| DRBG_STRENGTH128
,
149 .statelen
= 55, /* 440 bits */
153 .blocklen_bytes
= 20,
155 .backend_cra_name
= "sha1",
157 .flags
= DRBG_HASH
| DRBG_STRENGTH256
,
158 .statelen
= 111, /* 888 bits */
162 .blocklen_bytes
= 48,
163 .cra_name
= "sha384",
164 .backend_cra_name
= "sha384",
166 .flags
= DRBG_HASH
| DRBG_STRENGTH256
,
167 .statelen
= 111, /* 888 bits */
171 .blocklen_bytes
= 64,
172 .cra_name
= "sha512",
173 .backend_cra_name
= "sha512",
175 .flags
= DRBG_HASH
| DRBG_STRENGTH256
,
176 .statelen
= 55, /* 440 bits */
180 .blocklen_bytes
= 32,
181 .cra_name
= "sha256",
182 .backend_cra_name
= "sha256",
184 #endif /* CONFIG_CRYPTO_DRBG_HASH */
185 #ifdef CONFIG_CRYPTO_DRBG_HMAC
187 .flags
= DRBG_HMAC
| DRBG_STRENGTH256
,
188 .statelen
= 20, /* block length of cipher */
192 .blocklen_bytes
= 20,
193 .cra_name
= "hmac_sha1",
194 .backend_cra_name
= "hmac(sha1)",
196 .flags
= DRBG_HMAC
| DRBG_STRENGTH256
,
197 .statelen
= 48, /* block length of cipher */
201 .blocklen_bytes
= 48,
202 .cra_name
= "hmac_sha384",
203 .backend_cra_name
= "hmac(sha384)",
205 .flags
= DRBG_HMAC
| DRBG_STRENGTH256
,
206 .statelen
= 64, /* block length of cipher */
210 .blocklen_bytes
= 64,
211 .cra_name
= "hmac_sha512",
212 .backend_cra_name
= "hmac(sha512)",
214 .flags
= DRBG_HMAC
| DRBG_STRENGTH256
,
215 .statelen
= 32, /* block length of cipher */
219 .blocklen_bytes
= 32,
220 .cra_name
= "hmac_sha256",
221 .backend_cra_name
= "hmac(sha256)",
223 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
226 /******************************************************************
227 * Generic helper functions
228 ******************************************************************/
231 * Return strength of DRBG according to SP800-90A section 8.4
233 * @flags DRBG flags reference
235 * Return: normalized strength in *bytes* value or 32 as default
236 * to counter programming errors
238 static inline unsigned short drbg_sec_strength(drbg_flag_t flags
)
240 switch (flags
& DRBG_STRENGTH_MASK
) {
241 case DRBG_STRENGTH128
:
243 case DRBG_STRENGTH192
:
245 case DRBG_STRENGTH256
:
253 * FIPS 140-2 continuous self test
254 * The test is performed on the result of one round of the output
255 * function. Thus, the function implicitly knows the size of the
258 * The FIPS test can be called in an endless loop until it returns
259 * true. Although the code looks like a potential for a deadlock, it
260 * is not the case, because returning a false cannot mathematically
261 * occur (except once when a reseed took place and the updated state
262 * would is now set up such that the generation of new value returns
263 * an identical one -- this is most unlikely and would happen only once).
264 * Thus, if this function repeatedly returns false and thus would cause
265 * a deadlock, the integrity of the entire kernel is lost.
268 * @buf output buffer of random data to be checked
274 static bool drbg_fips_continuous_test(struct drbg_state
*drbg
,
275 const unsigned char *buf
)
277 #ifdef CONFIG_CRYPTO_FIPS
279 /* skip test if we test the overall system */
282 /* only perform test in FIPS mode */
283 if (0 == fips_enabled
)
285 if (!drbg
->fips_primed
) {
286 /* Priming of FIPS test */
287 memcpy(drbg
->prev
, buf
, drbg_blocklen(drbg
));
288 drbg
->fips_primed
= true;
289 /* return false due to priming, i.e. another round is needed */
292 ret
= memcmp(drbg
->prev
, buf
, drbg_blocklen(drbg
));
293 memcpy(drbg
->prev
, buf
, drbg_blocklen(drbg
));
294 /* the test shall pass when the two compared values are not equal */
298 #endif /* CONFIG_CRYPTO_FIPS */
302 * Convert an integer into a byte representation of this integer.
303 * The byte representation is big-endian
305 * @buf buffer holding the converted integer
306 * @val value to be converted
307 * @buflen length of buffer
309 #if (defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR))
310 static inline void drbg_int2byte(unsigned char *buf
, uint64_t val
,
316 byte
= buf
+ (buflen
- 1);
317 for (i
= 0; i
< buflen
; i
++)
318 *(byte
--) = val
>> (i
* 8) & 0xff;
324 * @dst buffer to increment
327 static inline void drbg_add_buf(unsigned char *dst
, size_t dstlen
,
328 const unsigned char *add
, size_t addlen
)
330 /* implied: dstlen > addlen */
331 unsigned char *dstptr
;
332 const unsigned char *addptr
;
333 unsigned int remainder
= 0;
336 dstptr
= dst
+ (dstlen
-1);
337 addptr
= add
+ (addlen
-1);
339 remainder
+= *dstptr
+ *addptr
;
340 *dstptr
= remainder
& 0xff;
342 len
--; dstptr
--; addptr
--;
344 len
= dstlen
- addlen
;
345 while (len
&& remainder
> 0) {
346 remainder
= *dstptr
+ 1;
347 *dstptr
= remainder
& 0xff;
352 #endif /* defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR) */
354 /******************************************************************
355 * CTR DRBG callback functions
356 ******************************************************************/
358 #ifdef CONFIG_CRYPTO_DRBG_CTR
359 #define CRYPTO_DRBG_CTR_STRING "CTR "
360 static int drbg_kcapi_sym(struct drbg_state
*drbg
, const unsigned char *key
,
361 unsigned char *outval
, const struct drbg_string
*in
);
362 static int drbg_init_sym_kernel(struct drbg_state
*drbg
);
363 static int drbg_fini_sym_kernel(struct drbg_state
*drbg
);
365 /* BCC function for CTR DRBG as defined in 10.4.3 */
366 static int drbg_ctr_bcc(struct drbg_state
*drbg
,
367 unsigned char *out
, const unsigned char *key
,
368 struct list_head
*in
)
371 struct drbg_string
*curr
= NULL
;
372 struct drbg_string data
;
375 drbg_string_fill(&data
, out
, drbg_blocklen(drbg
));
378 memset(out
, 0, drbg_blocklen(drbg
));
380 /* 10.4.3 step 2 / 4 */
381 list_for_each_entry(curr
, in
, list
) {
382 const unsigned char *pos
= curr
->buf
;
383 size_t len
= curr
->len
;
384 /* 10.4.3 step 4.1 */
386 /* 10.4.3 step 4.2 */
387 if (drbg_blocklen(drbg
) == cnt
) {
389 ret
= drbg_kcapi_sym(drbg
, key
, out
, &data
);
399 /* 10.4.3 step 4.2 for last block */
401 ret
= drbg_kcapi_sym(drbg
, key
, out
, &data
);
407 * scratchpad usage: drbg_ctr_update is interlinked with drbg_ctr_df
408 * (and drbg_ctr_bcc, but this function does not need any temporary buffers),
409 * the scratchpad is used as follows:
412 * start: drbg->scratchpad
413 * length: drbg_statelen(drbg) + drbg_blocklen(drbg)
414 * note: the cipher writing into this variable works
415 * blocklen-wise. Now, when the statelen is not a multiple
416 * of blocklen, the generateion loop below "spills over"
417 * by at most blocklen. Thus, we need to give sufficient
420 * start: drbg->scratchpad +
421 * drbg_statelen(drbg) + drbg_blocklen(drbg)
422 * length: drbg_statelen(drbg)
426 * start: df_data + drbg_statelen(drbg)
427 * length: drbg_blocklen(drbg)
429 * start: pad + drbg_blocklen(drbg)
430 * length: drbg_blocklen(drbg)
432 * start: iv + drbg_blocklen(drbg)
433 * length: drbg_satelen(drbg) + drbg_blocklen(drbg)
434 * note: temp is the buffer that the BCC function operates
435 * on. BCC operates blockwise. drbg_statelen(drbg)
436 * is sufficient when the DRBG state length is a multiple
437 * of the block size. For AES192 (and maybe other ciphers)
438 * this is not correct and the length for temp is
439 * insufficient (yes, that also means for such ciphers,
440 * the final output of all BCC rounds are truncated).
441 * Therefore, add drbg_blocklen(drbg) to cover all
445 /* Derivation Function for CTR DRBG as defined in 10.4.2 */
446 static int drbg_ctr_df(struct drbg_state
*drbg
,
447 unsigned char *df_data
, size_t bytes_to_return
,
448 struct list_head
*seedlist
)
451 unsigned char L_N
[8];
453 struct drbg_string S1
, S2
, S4
, cipherin
;
455 unsigned char *pad
= df_data
+ drbg_statelen(drbg
);
456 unsigned char *iv
= pad
+ drbg_blocklen(drbg
);
457 unsigned char *temp
= iv
+ drbg_blocklen(drbg
);
459 unsigned int templen
= 0;
463 const unsigned char *K
= (unsigned char *)
464 "\x00\x01\x02\x03\x04\x05\x06\x07"
465 "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
466 "\x10\x11\x12\x13\x14\x15\x16\x17"
467 "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f";
469 size_t generated_len
= 0;
471 struct drbg_string
*seed
= NULL
;
473 memset(pad
, 0, drbg_blocklen(drbg
));
474 memset(iv
, 0, drbg_blocklen(drbg
));
475 memset(temp
, 0, drbg_statelen(drbg
));
477 /* 10.4.2 step 1 is implicit as we work byte-wise */
480 if ((512/8) < bytes_to_return
)
483 /* 10.4.2 step 2 -- calculate the entire length of all input data */
484 list_for_each_entry(seed
, seedlist
, list
)
485 inputlen
+= seed
->len
;
486 drbg_int2byte(&L_N
[0], inputlen
, 4);
489 drbg_int2byte(&L_N
[4], bytes_to_return
, 4);
491 /* 10.4.2 step 5: length is L_N, input_string, one byte, padding */
492 padlen
= (inputlen
+ sizeof(L_N
) + 1) % (drbg_blocklen(drbg
));
493 /* wrap the padlen appropriately */
495 padlen
= drbg_blocklen(drbg
) - padlen
;
497 * pad / padlen contains the 0x80 byte and the following zero bytes.
498 * As the calculated padlen value only covers the number of zero
499 * bytes, this value has to be incremented by one for the 0x80 byte.
504 /* 10.4.2 step 4 -- first fill the linked list and then order it */
505 drbg_string_fill(&S1
, iv
, drbg_blocklen(drbg
));
506 list_add_tail(&S1
.list
, &bcc_list
);
507 drbg_string_fill(&S2
, L_N
, sizeof(L_N
));
508 list_add_tail(&S2
.list
, &bcc_list
);
509 list_splice_tail(seedlist
, &bcc_list
);
510 drbg_string_fill(&S4
, pad
, padlen
);
511 list_add_tail(&S4
.list
, &bcc_list
);
514 while (templen
< (drbg_keylen(drbg
) + (drbg_blocklen(drbg
)))) {
516 * 10.4.2 step 9.1 - the padding is implicit as the buffer
517 * holds zeros after allocation -- even the increment of i
518 * is irrelevant as the increment remains within length of i
520 drbg_int2byte(iv
, i
, 4);
521 /* 10.4.2 step 9.2 -- BCC and concatenation with temp */
522 ret
= drbg_ctr_bcc(drbg
, temp
+ templen
, K
, &bcc_list
);
525 /* 10.4.2 step 9.3 */
527 templen
+= drbg_blocklen(drbg
);
531 X
= temp
+ (drbg_keylen(drbg
));
532 drbg_string_fill(&cipherin
, X
, drbg_blocklen(drbg
));
534 /* 10.4.2 step 12: overwriting of outval is implemented in next step */
537 while (generated_len
< bytes_to_return
) {
540 * 10.4.2 step 13.1: the truncation of the key length is
541 * implicit as the key is only drbg_blocklen in size based on
542 * the implementation of the cipher function callback
544 ret
= drbg_kcapi_sym(drbg
, temp
, X
, &cipherin
);
547 blocklen
= (drbg_blocklen(drbg
) <
548 (bytes_to_return
- generated_len
)) ?
549 drbg_blocklen(drbg
) :
550 (bytes_to_return
- generated_len
);
551 /* 10.4.2 step 13.2 and 14 */
552 memcpy(df_data
+ generated_len
, X
, blocklen
);
553 generated_len
+= blocklen
;
559 memset(iv
, 0, drbg_blocklen(drbg
));
560 memset(temp
, 0, drbg_statelen(drbg
));
561 memset(pad
, 0, drbg_blocklen(drbg
));
566 * update function of CTR DRBG as defined in 10.2.1.2
568 * The reseed variable has an enhanced meaning compared to the update
569 * functions of the other DRBGs as follows:
570 * 0 => initial seed from initialization
571 * 1 => reseed via drbg_seed
572 * 2 => first invocation from drbg_ctr_update when addtl is present. In
573 * this case, the df_data scratchpad is not deleted so that it is
574 * available for another calls to prevent calling the DF function
576 * 3 => second invocation from drbg_ctr_update. When the update function
577 * was called with addtl, the df_data memory already contains the
578 * DFed addtl information and we do not need to call DF again.
580 static int drbg_ctr_update(struct drbg_state
*drbg
, struct list_head
*seed
,
584 /* 10.2.1.2 step 1 */
585 unsigned char *temp
= drbg
->scratchpad
;
586 unsigned char *df_data
= drbg
->scratchpad
+ drbg_statelen(drbg
) +
588 unsigned char *temp_p
, *df_data_p
; /* pointer to iterate over buffers */
589 unsigned int len
= 0;
590 struct drbg_string cipherin
;
591 unsigned char prefix
= DRBG_PREFIX1
;
593 memset(temp
, 0, drbg_statelen(drbg
) + drbg_blocklen(drbg
));
595 memset(df_data
, 0, drbg_statelen(drbg
));
597 /* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */
599 ret
= drbg_ctr_df(drbg
, df_data
, drbg_statelen(drbg
), seed
);
604 drbg_string_fill(&cipherin
, drbg
->V
, drbg_blocklen(drbg
));
606 * 10.2.1.3.2 steps 2 and 3 are already covered as the allocation
607 * zeroizes all memory during initialization
609 while (len
< (drbg_statelen(drbg
))) {
610 /* 10.2.1.2 step 2.1 */
611 drbg_add_buf(drbg
->V
, drbg_blocklen(drbg
), &prefix
, 1);
613 * 10.2.1.2 step 2.2 */
614 ret
= drbg_kcapi_sym(drbg
, drbg
->C
, temp
+ len
, &cipherin
);
617 /* 10.2.1.2 step 2.3 and 3 */
618 len
+= drbg_blocklen(drbg
);
621 /* 10.2.1.2 step 4 */
624 for (len
= 0; len
< drbg_statelen(drbg
); len
++) {
625 *temp_p
^= *df_data_p
;
626 df_data_p
++; temp_p
++;
629 /* 10.2.1.2 step 5 */
630 memcpy(drbg
->C
, temp
, drbg_keylen(drbg
));
631 /* 10.2.1.2 step 6 */
632 memcpy(drbg
->V
, temp
+ drbg_keylen(drbg
), drbg_blocklen(drbg
));
636 memset(temp
, 0, drbg_statelen(drbg
) + drbg_blocklen(drbg
));
638 memset(df_data
, 0, drbg_statelen(drbg
));
643 * scratchpad use: drbg_ctr_update is called independently from
644 * drbg_ctr_extract_bytes. Therefore, the scratchpad is reused
646 /* Generate function of CTR DRBG as defined in 10.2.1.5.2 */
647 static int drbg_ctr_generate(struct drbg_state
*drbg
,
648 unsigned char *buf
, unsigned int buflen
,
649 struct drbg_string
*addtl
)
653 struct drbg_string data
;
654 unsigned char prefix
= DRBG_PREFIX1
;
656 memset(drbg
->scratchpad
, 0, drbg_blocklen(drbg
));
658 /* 10.2.1.5.2 step 2 */
659 if (addtl
&& 0 < addtl
->len
) {
660 LIST_HEAD(addtllist
);
662 list_add_tail(&addtl
->list
, &addtllist
);
663 ret
= drbg_ctr_update(drbg
, &addtllist
, 2);
668 /* 10.2.1.5.2 step 4.1 */
669 drbg_add_buf(drbg
->V
, drbg_blocklen(drbg
), &prefix
, 1);
670 drbg_string_fill(&data
, drbg
->V
, drbg_blocklen(drbg
));
671 while (len
< buflen
) {
673 /* 10.2.1.5.2 step 4.2 */
674 ret
= drbg_kcapi_sym(drbg
, drbg
->C
, drbg
->scratchpad
, &data
);
679 outlen
= (drbg_blocklen(drbg
) < (buflen
- len
)) ?
680 drbg_blocklen(drbg
) : (buflen
- len
);
681 if (!drbg_fips_continuous_test(drbg
, drbg
->scratchpad
)) {
682 /* 10.2.1.5.2 step 6 */
683 drbg_add_buf(drbg
->V
, drbg_blocklen(drbg
), &prefix
, 1);
686 /* 10.2.1.5.2 step 4.3 */
687 memcpy(buf
+ len
, drbg
->scratchpad
, outlen
);
689 /* 10.2.1.5.2 step 6 */
691 drbg_add_buf(drbg
->V
, drbg_blocklen(drbg
), &prefix
, 1);
694 /* 10.2.1.5.2 step 6 */
695 ret
= drbg_ctr_update(drbg
, NULL
, 3);
700 memset(drbg
->scratchpad
, 0, drbg_blocklen(drbg
));
704 static struct drbg_state_ops drbg_ctr_ops
= {
705 .update
= drbg_ctr_update
,
706 .generate
= drbg_ctr_generate
,
707 .crypto_init
= drbg_init_sym_kernel
,
708 .crypto_fini
= drbg_fini_sym_kernel
,
710 #endif /* CONFIG_CRYPTO_DRBG_CTR */
712 /******************************************************************
713 * HMAC DRBG callback functions
714 ******************************************************************/
716 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
717 static int drbg_kcapi_hash(struct drbg_state
*drbg
, const unsigned char *key
,
718 unsigned char *outval
, const struct list_head
*in
);
719 static int drbg_init_hash_kernel(struct drbg_state
*drbg
);
720 static int drbg_fini_hash_kernel(struct drbg_state
*drbg
);
721 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
723 #ifdef CONFIG_CRYPTO_DRBG_HMAC
724 #define CRYPTO_DRBG_HMAC_STRING "HMAC "
725 /* update function of HMAC DRBG as defined in 10.1.2.2 */
726 static int drbg_hmac_update(struct drbg_state
*drbg
, struct list_head
*seed
,
731 struct drbg_string seed1
, seed2
, vdata
;
733 LIST_HEAD(vdatalist
);
736 /* 10.1.2.3 step 2 */
737 memset(drbg
->C
, 0, drbg_statelen(drbg
));
738 memset(drbg
->V
, 1, drbg_statelen(drbg
));
741 drbg_string_fill(&seed1
, drbg
->V
, drbg_statelen(drbg
));
742 list_add_tail(&seed1
.list
, &seedlist
);
743 /* buffer of seed2 will be filled in for loop below with one byte */
744 drbg_string_fill(&seed2
, NULL
, 1);
745 list_add_tail(&seed2
.list
, &seedlist
);
746 /* input data of seed is allowed to be NULL at this point */
748 list_splice_tail(seed
, &seedlist
);
750 drbg_string_fill(&vdata
, drbg
->V
, drbg_statelen(drbg
));
751 list_add_tail(&vdata
.list
, &vdatalist
);
752 for (i
= 2; 0 < i
; i
--) {
753 /* first round uses 0x0, second 0x1 */
754 unsigned char prefix
= DRBG_PREFIX0
;
756 prefix
= DRBG_PREFIX1
;
757 /* 10.1.2.2 step 1 and 4 -- concatenation and HMAC for key */
759 ret
= drbg_kcapi_hash(drbg
, drbg
->C
, drbg
->C
, &seedlist
);
763 /* 10.1.2.2 step 2 and 5 -- HMAC for V */
764 ret
= drbg_kcapi_hash(drbg
, drbg
->C
, drbg
->V
, &vdatalist
);
768 /* 10.1.2.2 step 3 */
776 /* generate function of HMAC DRBG as defined in 10.1.2.5 */
777 static int drbg_hmac_generate(struct drbg_state
*drbg
,
780 struct drbg_string
*addtl
)
784 struct drbg_string data
;
787 /* 10.1.2.5 step 2 */
788 if (addtl
&& 0 < addtl
->len
) {
789 LIST_HEAD(addtllist
);
791 list_add_tail(&addtl
->list
, &addtllist
);
792 ret
= drbg_hmac_update(drbg
, &addtllist
, 1);
797 drbg_string_fill(&data
, drbg
->V
, drbg_statelen(drbg
));
798 list_add_tail(&data
.list
, &datalist
);
799 while (len
< buflen
) {
800 unsigned int outlen
= 0;
801 /* 10.1.2.5 step 4.1 */
802 ret
= drbg_kcapi_hash(drbg
, drbg
->C
, drbg
->V
, &datalist
);
805 outlen
= (drbg_blocklen(drbg
) < (buflen
- len
)) ?
806 drbg_blocklen(drbg
) : (buflen
- len
);
807 if (!drbg_fips_continuous_test(drbg
, drbg
->V
))
810 /* 10.1.2.5 step 4.2 */
811 memcpy(buf
+ len
, drbg
->V
, outlen
);
815 /* 10.1.2.5 step 6 */
816 if (addtl
&& 0 < addtl
->len
) {
817 LIST_HEAD(addtllist
);
819 list_add_tail(&addtl
->list
, &addtllist
);
820 ret
= drbg_hmac_update(drbg
, &addtllist
, 1);
822 ret
= drbg_hmac_update(drbg
, NULL
, 1);
830 static struct drbg_state_ops drbg_hmac_ops
= {
831 .update
= drbg_hmac_update
,
832 .generate
= drbg_hmac_generate
,
833 .crypto_init
= drbg_init_hash_kernel
,
834 .crypto_fini
= drbg_fini_hash_kernel
,
837 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
839 /******************************************************************
840 * Hash DRBG callback functions
841 ******************************************************************/
843 #ifdef CONFIG_CRYPTO_DRBG_HASH
844 #define CRYPTO_DRBG_HASH_STRING "HASH "
846 * scratchpad usage: as drbg_hash_update and drbg_hash_df are used
847 * interlinked, the scratchpad is used as follows:
849 * start: drbg->scratchpad
850 * length: drbg_statelen(drbg)
852 * start: drbg->scratchpad + drbg_statelen(drbg)
853 * length: drbg_blocklen(drbg)
855 * drbg_hash_process_addtl uses the scratchpad, but fully completes
856 * before either of the functions mentioned before are invoked. Therefore,
857 * drbg_hash_process_addtl does not need to be specifically considered.
860 /* Derivation Function for Hash DRBG as defined in 10.4.1 */
861 static int drbg_hash_df(struct drbg_state
*drbg
,
862 unsigned char *outval
, size_t outlen
,
863 struct list_head
*entropylist
)
867 unsigned char input
[5];
868 unsigned char *tmp
= drbg
->scratchpad
+ drbg_statelen(drbg
);
869 struct drbg_string data
;
871 memset(tmp
, 0, drbg_blocklen(drbg
));
875 drbg_int2byte(&input
[1], (outlen
* 8), 4);
877 /* 10.4.1 step 4.1 -- concatenation of data for input into hash */
878 drbg_string_fill(&data
, input
, 5);
879 list_add(&data
.list
, entropylist
);
882 while (len
< outlen
) {
884 /* 10.4.1 step 4.1 */
885 ret
= drbg_kcapi_hash(drbg
, NULL
, tmp
, entropylist
);
888 /* 10.4.1 step 4.2 */
890 blocklen
= (drbg_blocklen(drbg
) < (outlen
- len
)) ?
891 drbg_blocklen(drbg
) : (outlen
- len
);
892 memcpy(outval
+ len
, tmp
, blocklen
);
897 memset(tmp
, 0, drbg_blocklen(drbg
));
901 /* update function for Hash DRBG as defined in 10.1.1.2 / 10.1.1.3 */
902 static int drbg_hash_update(struct drbg_state
*drbg
, struct list_head
*seed
,
906 struct drbg_string data1
, data2
;
908 LIST_HEAD(datalist2
);
909 unsigned char *V
= drbg
->scratchpad
;
910 unsigned char prefix
= DRBG_PREFIX1
;
912 memset(drbg
->scratchpad
, 0, drbg_statelen(drbg
));
917 /* 10.1.1.3 step 1 */
918 memcpy(V
, drbg
->V
, drbg_statelen(drbg
));
919 drbg_string_fill(&data1
, &prefix
, 1);
920 list_add_tail(&data1
.list
, &datalist
);
921 drbg_string_fill(&data2
, V
, drbg_statelen(drbg
));
922 list_add_tail(&data2
.list
, &datalist
);
924 list_splice_tail(seed
, &datalist
);
926 /* 10.1.1.2 / 10.1.1.3 step 2 and 3 */
927 ret
= drbg_hash_df(drbg
, drbg
->V
, drbg_statelen(drbg
), &datalist
);
931 /* 10.1.1.2 / 10.1.1.3 step 4 */
932 prefix
= DRBG_PREFIX0
;
933 drbg_string_fill(&data1
, &prefix
, 1);
934 list_add_tail(&data1
.list
, &datalist2
);
935 drbg_string_fill(&data2
, drbg
->V
, drbg_statelen(drbg
));
936 list_add_tail(&data2
.list
, &datalist2
);
937 /* 10.1.1.2 / 10.1.1.3 step 4 */
938 ret
= drbg_hash_df(drbg
, drbg
->C
, drbg_statelen(drbg
), &datalist2
);
941 memset(drbg
->scratchpad
, 0, drbg_statelen(drbg
));
945 /* processing of additional information string for Hash DRBG */
946 static int drbg_hash_process_addtl(struct drbg_state
*drbg
,
947 struct drbg_string
*addtl
)
950 struct drbg_string data1
, data2
;
952 unsigned char prefix
= DRBG_PREFIX2
;
954 /* this is value w as per documentation */
955 memset(drbg
->scratchpad
, 0, drbg_blocklen(drbg
));
957 /* 10.1.1.4 step 2 */
958 if (!addtl
|| 0 == addtl
->len
)
961 /* 10.1.1.4 step 2a */
962 drbg_string_fill(&data1
, &prefix
, 1);
963 drbg_string_fill(&data2
, drbg
->V
, drbg_statelen(drbg
));
964 list_add_tail(&data1
.list
, &datalist
);
965 list_add_tail(&data2
.list
, &datalist
);
966 list_add_tail(&addtl
->list
, &datalist
);
967 ret
= drbg_kcapi_hash(drbg
, NULL
, drbg
->scratchpad
, &datalist
);
971 /* 10.1.1.4 step 2b */
972 drbg_add_buf(drbg
->V
, drbg_statelen(drbg
),
973 drbg
->scratchpad
, drbg_blocklen(drbg
));
976 memset(drbg
->scratchpad
, 0, drbg_blocklen(drbg
));
980 /* Hashgen defined in 10.1.1.4 */
981 static int drbg_hash_hashgen(struct drbg_state
*drbg
,
987 unsigned char *src
= drbg
->scratchpad
;
988 unsigned char *dst
= drbg
->scratchpad
+ drbg_statelen(drbg
);
989 struct drbg_string data
;
991 unsigned char prefix
= DRBG_PREFIX1
;
993 memset(src
, 0, drbg_statelen(drbg
));
994 memset(dst
, 0, drbg_blocklen(drbg
));
996 /* 10.1.1.4 step hashgen 2 */
997 memcpy(src
, drbg
->V
, drbg_statelen(drbg
));
999 drbg_string_fill(&data
, src
, drbg_statelen(drbg
));
1000 list_add_tail(&data
.list
, &datalist
);
1001 while (len
< buflen
) {
1002 unsigned int outlen
= 0;
1003 /* 10.1.1.4 step hashgen 4.1 */
1004 ret
= drbg_kcapi_hash(drbg
, NULL
, dst
, &datalist
);
1009 outlen
= (drbg_blocklen(drbg
) < (buflen
- len
)) ?
1010 drbg_blocklen(drbg
) : (buflen
- len
);
1011 if (!drbg_fips_continuous_test(drbg
, dst
)) {
1012 drbg_add_buf(src
, drbg_statelen(drbg
), &prefix
, 1);
1015 /* 10.1.1.4 step hashgen 4.2 */
1016 memcpy(buf
+ len
, dst
, outlen
);
1018 /* 10.1.1.4 hashgen step 4.3 */
1020 drbg_add_buf(src
, drbg_statelen(drbg
), &prefix
, 1);
1024 memset(drbg
->scratchpad
, 0,
1025 (drbg_statelen(drbg
) + drbg_blocklen(drbg
)));
1029 /* generate function for Hash DRBG as defined in 10.1.1.4 */
1030 static int drbg_hash_generate(struct drbg_state
*drbg
,
1031 unsigned char *buf
, unsigned int buflen
,
1032 struct drbg_string
*addtl
)
1036 unsigned char req
[8];
1037 unsigned char prefix
= DRBG_PREFIX3
;
1038 struct drbg_string data1
, data2
;
1039 LIST_HEAD(datalist
);
1041 /* 10.1.1.4 step 2 */
1042 ret
= drbg_hash_process_addtl(drbg
, addtl
);
1045 /* 10.1.1.4 step 3 */
1046 len
= drbg_hash_hashgen(drbg
, buf
, buflen
);
1048 /* this is the value H as documented in 10.1.1.4 */
1049 memset(drbg
->scratchpad
, 0, drbg_blocklen(drbg
));
1050 /* 10.1.1.4 step 4 */
1051 drbg_string_fill(&data1
, &prefix
, 1);
1052 list_add_tail(&data1
.list
, &datalist
);
1053 drbg_string_fill(&data2
, drbg
->V
, drbg_statelen(drbg
));
1054 list_add_tail(&data2
.list
, &datalist
);
1055 ret
= drbg_kcapi_hash(drbg
, NULL
, drbg
->scratchpad
, &datalist
);
1061 /* 10.1.1.4 step 5 */
1062 drbg_add_buf(drbg
->V
, drbg_statelen(drbg
),
1063 drbg
->scratchpad
, drbg_blocklen(drbg
));
1064 drbg_add_buf(drbg
->V
, drbg_statelen(drbg
),
1065 drbg
->C
, drbg_statelen(drbg
));
1066 drbg_int2byte(req
, drbg
->reseed_ctr
, sizeof(req
));
1067 drbg_add_buf(drbg
->V
, drbg_statelen(drbg
), req
, 8);
1070 memset(drbg
->scratchpad
, 0, drbg_blocklen(drbg
));
1075 * scratchpad usage: as update and generate are used isolated, both
1076 * can use the scratchpad
1078 static struct drbg_state_ops drbg_hash_ops
= {
1079 .update
= drbg_hash_update
,
1080 .generate
= drbg_hash_generate
,
1081 .crypto_init
= drbg_init_hash_kernel
,
1082 .crypto_fini
= drbg_fini_hash_kernel
,
1084 #endif /* CONFIG_CRYPTO_DRBG_HASH */
1086 /******************************************************************
1087 * Functions common for DRBG implementations
1088 ******************************************************************/
1091 * Seeding or reseeding of the DRBG
1093 * @drbg: DRBG state struct
1094 * @pers: personalization / additional information buffer
1095 * @reseed: 0 for initial seed process, 1 for reseeding
1099 * error value otherwise
1101 static int drbg_seed(struct drbg_state
*drbg
, struct drbg_string
*pers
,
1105 unsigned char *entropy
= NULL
;
1106 size_t entropylen
= 0;
1107 struct drbg_string data1
;
1108 LIST_HEAD(seedlist
);
1110 /* 9.1 / 9.2 / 9.3.1 step 3 */
1111 if (pers
&& pers
->len
> (drbg_max_addtl(drbg
))) {
1112 pr_devel("DRBG: personalization string too long %zu\n",
1117 if (drbg
->test_data
&& drbg
->test_data
->testentropy
) {
1118 drbg_string_fill(&data1
, drbg
->test_data
->testentropy
->buf
,
1119 drbg
->test_data
->testentropy
->len
);
1120 pr_devel("DRBG: using test entropy\n");
1123 * Gather entropy equal to the security strength of the DRBG.
1124 * With a derivation function, a nonce is required in addition
1125 * to the entropy. A nonce must be at least 1/2 of the security
1126 * strength of the DRBG in size. Thus, entropy * nonce is 3/2
1127 * of the strength. The consideration of a nonce is only
1128 * applicable during initial seeding.
1130 entropylen
= drbg_sec_strength(drbg
->core
->flags
);
1134 entropylen
= ((entropylen
+ 1) / 2) * 3;
1135 pr_devel("DRBG: (re)seeding with %zu bytes of entropy\n",
1137 entropy
= kzalloc(entropylen
, GFP_KERNEL
);
1140 get_random_bytes(entropy
, entropylen
);
1141 drbg_string_fill(&data1
, entropy
, entropylen
);
1143 list_add_tail(&data1
.list
, &seedlist
);
1146 * concatenation of entropy with personalization str / addtl input)
1147 * the variable pers is directly handed in by the caller, so check its
1148 * contents whether it is appropriate
1150 if (pers
&& pers
->buf
&& 0 < pers
->len
) {
1151 list_add_tail(&pers
->list
, &seedlist
);
1152 pr_devel("DRBG: using personalization string\n");
1155 ret
= drbg
->d_ops
->update(drbg
, &seedlist
, reseed
);
1159 drbg
->seeded
= true;
1160 /* 10.1.1.2 / 10.1.1.3 step 5 */
1161 drbg
->reseed_ctr
= 1;
1169 /* Free all substructures in a DRBG state without the DRBG state structure */
1170 static inline void drbg_dealloc_state(struct drbg_state
*drbg
)
1180 if (drbg
->scratchpad
)
1181 kzfree(drbg
->scratchpad
);
1182 drbg
->scratchpad
= NULL
;
1183 drbg
->reseed_ctr
= 0;
1184 #ifdef CONFIG_CRYPTO_FIPS
1188 drbg
->fips_primed
= false;
1193 * Allocate all sub-structures for a DRBG state.
1194 * The DRBG state structure must already be allocated.
1196 static inline int drbg_alloc_state(struct drbg_state
*drbg
)
1199 unsigned int sb_size
= 0;
1204 drbg
->V
= kzalloc(drbg_statelen(drbg
), GFP_KERNEL
);
1207 drbg
->C
= kzalloc(drbg_statelen(drbg
), GFP_KERNEL
);
1210 #ifdef CONFIG_CRYPTO_FIPS
1211 drbg
->prev
= kzalloc(drbg_blocklen(drbg
), GFP_KERNEL
);
1214 drbg
->fips_primed
= false;
1216 /* scratchpad is only generated for CTR and Hash */
1217 if (drbg
->core
->flags
& DRBG_HMAC
)
1219 else if (drbg
->core
->flags
& DRBG_CTR
)
1220 sb_size
= drbg_statelen(drbg
) + drbg_blocklen(drbg
) + /* temp */
1221 drbg_statelen(drbg
) + /* df_data */
1222 drbg_blocklen(drbg
) + /* pad */
1223 drbg_blocklen(drbg
) + /* iv */
1224 drbg_statelen(drbg
) + drbg_blocklen(drbg
); /* temp */
1226 sb_size
= drbg_statelen(drbg
) + drbg_blocklen(drbg
);
1229 drbg
->scratchpad
= kzalloc(sb_size
, GFP_KERNEL
);
1230 if (!drbg
->scratchpad
)
1233 spin_lock_init(&drbg
->drbg_lock
);
1237 drbg_dealloc_state(drbg
);
1242 * Strategy to avoid holding long term locks: generate a shadow copy of DRBG
1243 * and perform all operations on this shadow copy. After finishing, restore
1244 * the updated state of the shadow copy into original drbg state. This way,
1245 * only the read and write operations of the original drbg state must be
1248 static inline void drbg_copy_drbg(struct drbg_state
*src
,
1249 struct drbg_state
*dst
)
1253 memcpy(dst
->V
, src
->V
, drbg_statelen(src
));
1254 memcpy(dst
->C
, src
->C
, drbg_statelen(src
));
1255 dst
->reseed_ctr
= src
->reseed_ctr
;
1256 dst
->seeded
= src
->seeded
;
1258 #ifdef CONFIG_CRYPTO_FIPS
1259 dst
->fips_primed
= src
->fips_primed
;
1260 memcpy(dst
->prev
, src
->prev
, drbg_blocklen(src
));
1264 * scratchpad is initialized drbg_alloc_state;
1265 * priv_data is initialized with call to crypto_init;
1266 * d_ops and core are set outside, as these parameters are const;
1267 * test_data is set outside to prevent it being copied back.
1271 static int drbg_make_shadow(struct drbg_state
*drbg
, struct drbg_state
**shadow
)
1274 struct drbg_state
*tmp
= NULL
;
1276 if (!drbg
|| !drbg
->core
|| !drbg
->V
|| !drbg
->C
) {
1277 pr_devel("DRBG: attempt to generate shadow copy for "
1278 "uninitialized DRBG state rejected\n");
1281 /* HMAC does not have a scratchpad */
1282 if (!(drbg
->core
->flags
& DRBG_HMAC
) && NULL
== drbg
->scratchpad
)
1285 tmp
= kzalloc(sizeof(struct drbg_state
), GFP_KERNEL
);
1289 /* read-only data as they are defined as const, no lock needed */
1290 tmp
->core
= drbg
->core
;
1291 tmp
->d_ops
= drbg
->d_ops
;
1293 ret
= drbg_alloc_state(tmp
);
1297 spin_lock_bh(&drbg
->drbg_lock
);
1298 drbg_copy_drbg(drbg
, tmp
);
1299 /* only make a link to the test buffer, as we only read that data */
1300 tmp
->test_data
= drbg
->test_data
;
1301 spin_unlock_bh(&drbg
->drbg_lock
);
1311 static void drbg_restore_shadow(struct drbg_state
*drbg
,
1312 struct drbg_state
**shadow
)
1314 struct drbg_state
*tmp
= *shadow
;
1316 spin_lock_bh(&drbg
->drbg_lock
);
1317 drbg_copy_drbg(tmp
, drbg
);
1318 spin_unlock_bh(&drbg
->drbg_lock
);
1319 drbg_dealloc_state(tmp
);
1324 /*************************************************************************
1325 * DRBG interface functions
1326 *************************************************************************/
1329 * DRBG generate function as required by SP800-90A - this function
1330 * generates random numbers
1332 * @drbg DRBG state handle
1333 * @buf Buffer where to store the random numbers -- the buffer must already
1334 * be pre-allocated by caller
1335 * @buflen Length of output buffer - this value defines the number of random
1336 * bytes pulled from DRBG
1337 * @addtl Additional input that is mixed into state, may be NULL -- note
1338 * the entropy is pulled by the DRBG internally unconditionally
1339 * as defined in SP800-90A. The additional input is mixed into
1340 * the state in addition to the pulled entropy.
1342 * return: generated number of bytes
1344 static int drbg_generate(struct drbg_state
*drbg
,
1345 unsigned char *buf
, unsigned int buflen
,
1346 struct drbg_string
*addtl
)
1349 struct drbg_state
*shadow
= NULL
;
1351 if (0 == buflen
|| !buf
) {
1352 pr_devel("DRBG: no output buffer provided\n");
1355 if (addtl
&& NULL
== addtl
->buf
&& 0 < addtl
->len
) {
1356 pr_devel("DRBG: wrong format of additional information\n");
1360 len
= drbg_make_shadow(drbg
, &shadow
);
1362 pr_devel("DRBG: shadow copy cannot be generated\n");
1368 if (buflen
> (drbg_max_request_bytes(shadow
))) {
1369 pr_devel("DRBG: requested random numbers too large %u\n",
1374 /* 9.3.1 step 3 is implicit with the chosen DRBG */
1377 if (addtl
&& addtl
->len
> (drbg_max_addtl(shadow
))) {
1378 pr_devel("DRBG: additional information string too long %zu\n",
1382 /* 9.3.1 step 5 is implicit with the chosen DRBG */
1385 * 9.3.1 step 6 and 9 supplemented by 9.3.2 step c is implemented
1386 * here. The spec is a bit convoluted here, we make it simpler.
1388 if ((drbg_max_requests(shadow
)) < shadow
->reseed_ctr
)
1389 shadow
->seeded
= false;
1391 /* allocate cipher handle */
1392 if (shadow
->d_ops
->crypto_init
) {
1393 len
= shadow
->d_ops
->crypto_init(shadow
);
1398 if (shadow
->pr
|| !shadow
->seeded
) {
1399 pr_devel("DRBG: reseeding before generation (prediction "
1400 "resistance: %s, state %s)\n",
1401 drbg
->pr
? "true" : "false",
1402 drbg
->seeded
? "seeded" : "unseeded");
1403 /* 9.3.1 steps 7.1 through 7.3 */
1404 len
= drbg_seed(shadow
, addtl
, true);
1407 /* 9.3.1 step 7.4 */
1410 /* 9.3.1 step 8 and 10 */
1411 len
= shadow
->d_ops
->generate(shadow
, buf
, buflen
, addtl
);
1413 /* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */
1414 shadow
->reseed_ctr
++;
1419 * Section 11.3.3 requires to re-perform self tests after some
1420 * generated random numbers. The chosen value after which self
1421 * test is performed is arbitrary, but it should be reasonable.
1422 * However, we do not perform the self tests because of the following
1423 * reasons: it is mathematically impossible that the initial self tests
1424 * were successfully and the following are not. If the initial would
1425 * pass and the following would not, the kernel integrity is violated.
1426 * In this case, the entire kernel operation is questionable and it
1427 * is unlikely that the integrity violation only affects the
1428 * correct operation of the DRBG.
1430 * Albeit the following code is commented out, it is provided in
1431 * case somebody has a need to implement the test of 11.3.3.
1434 if (shadow
->reseed_ctr
&& !(shadow
->reseed_ctr
% 4096)) {
1436 pr_devel("DRBG: start to perform self test\n");
1437 if (drbg
->core
->flags
& DRBG_HMAC
)
1438 err
= alg_test("drbg_pr_hmac_sha256",
1439 "drbg_pr_hmac_sha256", 0, 0);
1440 else if (drbg
->core
->flags
& DRBG_CTR
)
1441 err
= alg_test("drbg_pr_ctr_aes128",
1442 "drbg_pr_ctr_aes128", 0, 0);
1444 err
= alg_test("drbg_pr_sha256",
1445 "drbg_pr_sha256", 0, 0);
1447 pr_err("DRBG: periodical self test failed\n");
1449 * uninstantiate implies that from now on, only errors
1450 * are returned when reusing this DRBG cipher handle
1452 drbg_uninstantiate(drbg
);
1453 drbg_dealloc_state(shadow
);
1457 pr_devel("DRBG: self test successful\n");
1463 if (shadow
->d_ops
->crypto_fini
)
1464 shadow
->d_ops
->crypto_fini(shadow
);
1465 drbg_restore_shadow(drbg
, &shadow
);
1470 * Wrapper around drbg_generate which can pull arbitrary long strings
1471 * from the DRBG without hitting the maximum request limitation.
1473 * Parameters: see drbg_generate
1474 * Return codes: see drbg_generate -- if one drbg_generate request fails,
1475 * the entire drbg_generate_long request fails
1477 static int drbg_generate_long(struct drbg_state
*drbg
,
1478 unsigned char *buf
, unsigned int buflen
,
1479 struct drbg_string
*addtl
)
1482 unsigned int slice
= 0;
1485 unsigned int chunk
= 0;
1486 slice
= ((buflen
- len
) / drbg_max_request_bytes(drbg
));
1487 chunk
= slice
? drbg_max_request_bytes(drbg
) : (buflen
- len
);
1488 tmplen
= drbg_generate(drbg
, buf
+ len
, chunk
, addtl
);
1492 } while (slice
> 0);
1497 * DRBG instantiation function as required by SP800-90A - this function
1498 * sets up the DRBG handle, performs the initial seeding and all sanity
1499 * checks required by SP800-90A
1501 * @drbg memory of state -- if NULL, new memory is allocated
1502 * @pers Personalization string that is mixed into state, may be NULL -- note
1503 * the entropy is pulled by the DRBG internally unconditionally
1504 * as defined in SP800-90A. The additional input is mixed into
1505 * the state in addition to the pulled entropy.
1506 * @coreref reference to core
1507 * @pr prediction resistance enabled
1511 * error value otherwise
1513 static int drbg_instantiate(struct drbg_state
*drbg
, struct drbg_string
*pers
,
1514 int coreref
, bool pr
)
1518 pr_devel("DRBG: Initializing DRBG core %d with prediction resistance "
1519 "%s\n", coreref
, pr
? "enabled" : "disabled");
1520 drbg
->core
= &drbg_cores
[coreref
];
1522 drbg
->seeded
= false;
1523 switch (drbg
->core
->flags
& DRBG_TYPE_MASK
) {
1524 #ifdef CONFIG_CRYPTO_DRBG_HMAC
1526 drbg
->d_ops
= &drbg_hmac_ops
;
1528 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
1529 #ifdef CONFIG_CRYPTO_DRBG_HASH
1531 drbg
->d_ops
= &drbg_hash_ops
;
1533 #endif /* CONFIG_CRYPTO_DRBG_HASH */
1534 #ifdef CONFIG_CRYPTO_DRBG_CTR
1536 drbg
->d_ops
= &drbg_ctr_ops
;
1538 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1543 /* 9.1 step 1 is implicit with the selected DRBG type */
1546 * 9.1 step 2 is implicit as caller can select prediction resistance
1547 * and the flag is copied into drbg->flags --
1548 * all DRBG types support prediction resistance
1551 /* 9.1 step 4 is implicit in drbg_sec_strength */
1553 ret
= drbg_alloc_state(drbg
);
1558 if (drbg
->d_ops
->crypto_init
&& drbg
->d_ops
->crypto_init(drbg
))
1560 ret
= drbg_seed(drbg
, pers
, false);
1561 if (drbg
->d_ops
->crypto_fini
)
1562 drbg
->d_ops
->crypto_fini(drbg
);
1569 drbg_dealloc_state(drbg
);
1574 * DRBG uninstantiate function as required by SP800-90A - this function
1575 * frees all buffers and the DRBG handle
1577 * @drbg DRBG state handle
1582 static int drbg_uninstantiate(struct drbg_state
*drbg
)
1584 spin_lock_bh(&drbg
->drbg_lock
);
1585 drbg_dealloc_state(drbg
);
1586 /* no scrubbing of test_data -- this shall survive an uninstantiate */
1587 spin_unlock_bh(&drbg
->drbg_lock
);
1592 * Helper function for setting the test data in the DRBG
1594 * @drbg DRBG state handle
1595 * @test_data test data to sets
1597 static inline void drbg_set_testdata(struct drbg_state
*drbg
,
1598 struct drbg_test_data
*test_data
)
1600 if (!test_data
|| !test_data
->testentropy
)
1602 spin_lock_bh(&drbg
->drbg_lock
);
1603 drbg
->test_data
= test_data
;
1604 spin_unlock_bh(&drbg
->drbg_lock
);
1607 /***************************************************************
1608 * Kernel crypto API cipher invocations requested by DRBG
1609 ***************************************************************/
1611 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
1613 struct shash_desc shash
;
1617 static int drbg_init_hash_kernel(struct drbg_state
*drbg
)
1619 struct sdesc
*sdesc
;
1620 struct crypto_shash
*tfm
;
1622 tfm
= crypto_alloc_shash(drbg
->core
->backend_cra_name
, 0, 0);
1624 pr_info("DRBG: could not allocate digest TFM handle\n");
1625 return PTR_ERR(tfm
);
1627 BUG_ON(drbg_blocklen(drbg
) != crypto_shash_digestsize(tfm
));
1628 sdesc
= kzalloc(sizeof(struct shash_desc
) + crypto_shash_descsize(tfm
),
1631 crypto_free_shash(tfm
);
1635 sdesc
->shash
.tfm
= tfm
;
1636 sdesc
->shash
.flags
= 0;
1637 drbg
->priv_data
= sdesc
;
1641 static int drbg_fini_hash_kernel(struct drbg_state
*drbg
)
1643 struct sdesc
*sdesc
= (struct sdesc
*)drbg
->priv_data
;
1645 crypto_free_shash(sdesc
->shash
.tfm
);
1648 drbg
->priv_data
= NULL
;
1652 static int drbg_kcapi_hash(struct drbg_state
*drbg
, const unsigned char *key
,
1653 unsigned char *outval
, const struct list_head
*in
)
1655 struct sdesc
*sdesc
= (struct sdesc
*)drbg
->priv_data
;
1656 struct drbg_string
*input
= NULL
;
1659 crypto_shash_setkey(sdesc
->shash
.tfm
, key
, drbg_statelen(drbg
));
1660 crypto_shash_init(&sdesc
->shash
);
1661 list_for_each_entry(input
, in
, list
)
1662 crypto_shash_update(&sdesc
->shash
, input
->buf
, input
->len
);
1663 return crypto_shash_final(&sdesc
->shash
, outval
);
1665 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
1667 #ifdef CONFIG_CRYPTO_DRBG_CTR
1668 static int drbg_init_sym_kernel(struct drbg_state
*drbg
)
1671 struct crypto_blkcipher
*tfm
;
1673 tfm
= crypto_alloc_blkcipher(drbg
->core
->backend_cra_name
, 0, 0);
1675 pr_info("DRBG: could not allocate cipher TFM handle\n");
1676 return PTR_ERR(tfm
);
1678 BUG_ON(drbg_blocklen(drbg
) != crypto_blkcipher_blocksize(tfm
));
1679 drbg
->priv_data
= tfm
;
1683 static int drbg_fini_sym_kernel(struct drbg_state
*drbg
)
1685 struct crypto_blkcipher
*tfm
=
1686 (struct crypto_blkcipher
*)drbg
->priv_data
;
1688 crypto_free_blkcipher(tfm
);
1689 drbg
->priv_data
= NULL
;
1693 static int drbg_kcapi_sym(struct drbg_state
*drbg
, const unsigned char *key
,
1694 unsigned char *outval
, const struct drbg_string
*in
)
1697 struct scatterlist sg_in
, sg_out
;
1698 struct blkcipher_desc desc
;
1699 struct crypto_blkcipher
*tfm
=
1700 (struct crypto_blkcipher
*)drbg
->priv_data
;
1704 crypto_blkcipher_setkey(tfm
, key
, (drbg_keylen(drbg
)));
1705 /* there is only component in *in */
1706 sg_init_one(&sg_in
, in
->buf
, in
->len
);
1707 sg_init_one(&sg_out
, outval
, drbg_blocklen(drbg
));
1708 ret
= crypto_blkcipher_encrypt(&desc
, &sg_out
, &sg_in
, in
->len
);
1712 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1714 /***************************************************************
1715 * Kernel crypto API interface to register DRBG
1716 ***************************************************************/
1719 * Look up the DRBG flags by given kernel crypto API cra_name
1720 * The code uses the drbg_cores definition to do this
1722 * @cra_name kernel crypto API cra_name
1723 * @coreref reference to integer which is filled with the pointer to
1724 * the applicable core
1725 * @pr reference for setting prediction resistance
1729 static inline void drbg_convert_tfm_core(const char *cra_driver_name
,
1730 int *coreref
, bool *pr
)
1737 /* disassemble the names */
1738 if (!memcmp(cra_driver_name
, "drbg_nopr_", 10)) {
1741 } else if (!memcmp(cra_driver_name
, "drbg_pr_", 8)) {
1747 /* remove the first part */
1748 len
= strlen(cra_driver_name
) - start
;
1749 for (i
= 0; ARRAY_SIZE(drbg_cores
) > i
; i
++) {
1750 if (!memcmp(cra_driver_name
+ start
, drbg_cores
[i
].cra_name
,
1758 static int drbg_kcapi_init(struct crypto_tfm
*tfm
)
1760 struct drbg_state
*drbg
= crypto_tfm_ctx(tfm
);
1764 drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm
), &coreref
, &pr
);
1766 * when personalization string is needed, the caller must call reset
1767 * and provide the personalization string as seed information
1769 return drbg_instantiate(drbg
, NULL
, coreref
, pr
);
1772 static void drbg_kcapi_cleanup(struct crypto_tfm
*tfm
)
1774 drbg_uninstantiate(crypto_tfm_ctx(tfm
));
1778 * Generate random numbers invoked by the kernel crypto API:
1779 * The API of the kernel crypto API is extended as follows:
1781 * If dlen is larger than zero, rdata is interpreted as the output buffer
1782 * where random data is to be stored.
1784 * If dlen is zero, rdata is interpreted as a pointer to a struct drbg_gen
1785 * which holds the additional information string that is used for the
1786 * DRBG generation process. The output buffer that is to be used to store
1787 * data is also pointed to by struct drbg_gen.
1789 static int drbg_kcapi_random(struct crypto_rng
*tfm
, u8
*rdata
,
1792 struct drbg_state
*drbg
= crypto_rng_ctx(tfm
);
1794 return drbg_generate_long(drbg
, rdata
, dlen
, NULL
);
1796 struct drbg_gen
*data
= (struct drbg_gen
*)rdata
;
1797 struct drbg_string addtl
;
1798 /* catch NULL pointer */
1801 drbg_set_testdata(drbg
, data
->test_data
);
1802 /* linked list variable is now local to allow modification */
1803 drbg_string_fill(&addtl
, data
->addtl
->buf
, data
->addtl
->len
);
1804 return drbg_generate_long(drbg
, data
->outbuf
, data
->outlen
,
1810 * Reset the DRBG invoked by the kernel crypto API
1811 * The reset implies a full re-initialization of the DRBG. Similar to the
1812 * generate function of drbg_kcapi_random, this function extends the
1813 * kernel crypto API interface with struct drbg_gen
1815 static int drbg_kcapi_reset(struct crypto_rng
*tfm
, u8
*seed
, unsigned int slen
)
1817 struct drbg_state
*drbg
= crypto_rng_ctx(tfm
);
1818 struct crypto_tfm
*tfm_base
= crypto_rng_tfm(tfm
);
1820 struct drbg_string seed_string
;
1823 drbg_uninstantiate(drbg
);
1824 drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base
), &coreref
,
1827 drbg_string_fill(&seed_string
, seed
, slen
);
1828 return drbg_instantiate(drbg
, &seed_string
, coreref
, pr
);
1830 struct drbg_gen
*data
= (struct drbg_gen
*)seed
;
1831 /* allow invocation of API call with NULL, 0 */
1833 return drbg_instantiate(drbg
, NULL
, coreref
, pr
);
1834 drbg_set_testdata(drbg
, data
->test_data
);
1835 /* linked list variable is now local to allow modification */
1836 drbg_string_fill(&seed_string
, data
->addtl
->buf
,
1838 return drbg_instantiate(drbg
, &seed_string
, coreref
, pr
);
1842 /***************************************************************
1843 * Kernel module: code to load the module
1844 ***************************************************************/
1847 * Tests as defined in 11.3.2 in addition to the cipher tests: testing
1848 * of the error handling.
1850 * Note: testing of failing seed source as defined in 11.3.2 is not applicable
1851 * as seed source of get_random_bytes does not fail.
1853 * Note 2: There is no sensible way of testing the reseed counter
1854 * enforcement, so skip it.
1856 static inline int __init
drbg_healthcheck_sanity(void)
1858 #ifdef CONFIG_CRYPTO_FIPS
1860 #define OUTBUFLEN 16
1861 unsigned char buf
[OUTBUFLEN
];
1862 struct drbg_state
*drbg
= NULL
;
1867 struct drbg_string addtl
;
1868 size_t max_addtllen
, max_request_bytes
;
1870 /* only perform test in FIPS mode */
1874 #ifdef CONFIG_CRYPTO_DRBG_CTR
1875 drbg_convert_tfm_core("drbg_nopr_ctr_aes128", &coreref
, &pr
);
1876 #elif defined CONFIG_CRYPTO_DRBG_HASH
1877 drbg_convert_tfm_core("drbg_nopr_sha256", &coreref
, &pr
);
1879 drbg_convert_tfm_core("drbg_nopr_hmac_sha256", &coreref
, &pr
);
1882 drbg
= kzalloc(sizeof(struct drbg_state
), GFP_KERNEL
);
1887 * if the following tests fail, it is likely that there is a buffer
1888 * overflow as buf is much smaller than the requested or provided
1889 * string lengths -- in case the error handling does not succeed
1890 * we may get an OOPS. And we want to get an OOPS as this is a
1894 /* get a valid instance of DRBG for following tests */
1895 ret
= drbg_instantiate(drbg
, NULL
, coreref
, pr
);
1900 max_addtllen
= drbg_max_addtl(drbg
);
1901 max_request_bytes
= drbg_max_request_bytes(drbg
);
1902 drbg_string_fill(&addtl
, buf
, max_addtllen
+ 1);
1903 /* overflow addtllen with additonal info string */
1904 len
= drbg_generate(drbg
, buf
, OUTBUFLEN
, &addtl
);
1906 /* overflow max_bits */
1907 len
= drbg_generate(drbg
, buf
, (max_request_bytes
+ 1), NULL
);
1909 drbg_uninstantiate(drbg
);
1911 /* overflow max addtllen with personalization string */
1912 ret
= drbg_instantiate(drbg
, &addtl
, coreref
, pr
);
1914 /* test uninstantated DRBG */
1915 len
= drbg_generate(drbg
, buf
, (max_request_bytes
+ 1), NULL
);
1917 /* all tests passed */
1920 pr_devel("DRBG: Sanity tests for failure code paths successfully "
1923 drbg_uninstantiate(drbg
);
1927 #else /* CONFIG_CRYPTO_FIPS */
1929 #endif /* CONFIG_CRYPTO_FIPS */
1932 static struct crypto_alg drbg_algs
[22];
1935 * Fill the array drbg_algs used to register the different DRBGs
1936 * with the kernel crypto API. To fill the array, the information
1937 * from drbg_cores[] is used.
1939 static inline void __init
drbg_fill_array(struct crypto_alg
*alg
,
1940 const struct drbg_core
*core
, int pr
)
1943 static int priority
= 100;
1945 memset(alg
, 0, sizeof(struct crypto_alg
));
1946 memcpy(alg
->cra_name
, "stdrng", 6);
1948 memcpy(alg
->cra_driver_name
, "drbg_pr_", 8);
1951 memcpy(alg
->cra_driver_name
, "drbg_nopr_", 10);
1954 memcpy(alg
->cra_driver_name
+ pos
, core
->cra_name
,
1955 strlen(core
->cra_name
));
1957 alg
->cra_priority
= priority
;
1960 * If FIPS mode enabled, the selected DRBG shall have the
1961 * highest cra_priority over other stdrng instances to ensure
1965 alg
->cra_priority
+= 200;
1967 alg
->cra_flags
= CRYPTO_ALG_TYPE_RNG
;
1968 alg
->cra_ctxsize
= sizeof(struct drbg_state
);
1969 alg
->cra_type
= &crypto_rng_type
;
1970 alg
->cra_module
= THIS_MODULE
;
1971 alg
->cra_init
= drbg_kcapi_init
;
1972 alg
->cra_exit
= drbg_kcapi_cleanup
;
1973 alg
->cra_u
.rng
.rng_make_random
= drbg_kcapi_random
;
1974 alg
->cra_u
.rng
.rng_reset
= drbg_kcapi_reset
;
1975 alg
->cra_u
.rng
.seedsize
= 0;
1978 static int __init
drbg_init(void)
1980 unsigned int i
= 0; /* pointer to drbg_algs */
1981 unsigned int j
= 0; /* pointer to drbg_cores */
1984 ret
= drbg_healthcheck_sanity();
1988 if (ARRAY_SIZE(drbg_cores
) * 2 > ARRAY_SIZE(drbg_algs
)) {
1989 pr_info("DRBG: Cannot register all DRBG types"
1990 "(slots needed: %zu, slots available: %zu)\n",
1991 ARRAY_SIZE(drbg_cores
) * 2, ARRAY_SIZE(drbg_algs
));
1996 * each DRBG definition can be used with PR and without PR, thus
1997 * we instantiate each DRBG in drbg_cores[] twice.
1999 * As the order of placing them into the drbg_algs array matters
2000 * (the later DRBGs receive a higher cra_priority) we register the
2001 * prediction resistance DRBGs first as the should not be too
2004 for (j
= 0; ARRAY_SIZE(drbg_cores
) > j
; j
++, i
++)
2005 drbg_fill_array(&drbg_algs
[i
], &drbg_cores
[j
], 1);
2006 for (j
= 0; ARRAY_SIZE(drbg_cores
) > j
; j
++, i
++)
2007 drbg_fill_array(&drbg_algs
[i
], &drbg_cores
[j
], 0);
2008 return crypto_register_algs(drbg_algs
, (ARRAY_SIZE(drbg_cores
) * 2));
2011 void __exit
drbg_exit(void)
2013 crypto_unregister_algs(drbg_algs
, (ARRAY_SIZE(drbg_cores
) * 2));
2016 module_init(drbg_init
);
2017 module_exit(drbg_exit
);
2018 #ifndef CRYPTO_DRBG_HASH_STRING
2019 #define CRYPTO_DRBG_HASH_STRING ""
2021 #ifndef CRYPTO_DRBG_HMAC_STRING
2022 #define CRYPTO_DRBG_HMAC_STRING ""
2024 #ifndef CRYPTO_DRBG_CTR_STRING
2025 #define CRYPTO_DRBG_CTR_STRING ""
2027 MODULE_LICENSE("GPL");
2028 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
2029 MODULE_DESCRIPTION("NIST SP800-90A Deterministic Random Bit Generator (DRBG) "
2030 "using following cores: "
2031 CRYPTO_DRBG_HASH_STRING
2032 CRYPTO_DRBG_HMAC_STRING
2033 CRYPTO_DRBG_CTR_STRING
);