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
));
565 /* update function of CTR DRBG as defined in 10.2.1.2 */
566 static int drbg_ctr_update(struct drbg_state
*drbg
, struct list_head
*seed
,
570 /* 10.2.1.2 step 1 */
571 unsigned char *temp
= drbg
->scratchpad
;
572 unsigned char *df_data
= drbg
->scratchpad
+ drbg_statelen(drbg
) +
574 unsigned char *temp_p
, *df_data_p
; /* pointer to iterate over buffers */
575 unsigned int len
= 0;
576 struct drbg_string cipherin
;
577 unsigned char prefix
= DRBG_PREFIX1
;
579 memset(temp
, 0, drbg_statelen(drbg
) + drbg_blocklen(drbg
));
580 memset(df_data
, 0, drbg_statelen(drbg
));
582 /* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */
584 ret
= drbg_ctr_df(drbg
, df_data
, drbg_statelen(drbg
), seed
);
589 drbg_string_fill(&cipherin
, drbg
->V
, drbg_blocklen(drbg
));
591 * 10.2.1.3.2 steps 2 and 3 are already covered as the allocation
592 * zeroizes all memory during initialization
594 while (len
< (drbg_statelen(drbg
))) {
595 /* 10.2.1.2 step 2.1 */
596 drbg_add_buf(drbg
->V
, drbg_blocklen(drbg
), &prefix
, 1);
598 * 10.2.1.2 step 2.2 */
599 ret
= drbg_kcapi_sym(drbg
, drbg
->C
, temp
+ len
, &cipherin
);
602 /* 10.2.1.2 step 2.3 and 3 */
603 len
+= drbg_blocklen(drbg
);
606 /* 10.2.1.2 step 4 */
609 for (len
= 0; len
< drbg_statelen(drbg
); len
++) {
610 *temp_p
^= *df_data_p
;
611 df_data_p
++; temp_p
++;
614 /* 10.2.1.2 step 5 */
615 memcpy(drbg
->C
, temp
, drbg_keylen(drbg
));
616 /* 10.2.1.2 step 6 */
617 memcpy(drbg
->V
, temp
+ drbg_keylen(drbg
), drbg_blocklen(drbg
));
621 memset(temp
, 0, drbg_statelen(drbg
) + drbg_blocklen(drbg
));
622 memset(df_data
, 0, drbg_statelen(drbg
));
627 * scratchpad use: drbg_ctr_update is called independently from
628 * drbg_ctr_extract_bytes. Therefore, the scratchpad is reused
630 /* Generate function of CTR DRBG as defined in 10.2.1.5.2 */
631 static int drbg_ctr_generate(struct drbg_state
*drbg
,
632 unsigned char *buf
, unsigned int buflen
,
633 struct drbg_string
*addtl
)
637 struct drbg_string data
;
638 unsigned char prefix
= DRBG_PREFIX1
;
640 memset(drbg
->scratchpad
, 0, drbg_blocklen(drbg
));
642 /* 10.2.1.5.2 step 2 */
643 if (addtl
&& 0 < addtl
->len
) {
644 LIST_HEAD(addtllist
);
646 list_add_tail(&addtl
->list
, &addtllist
);
647 ret
= drbg_ctr_update(drbg
, &addtllist
, 1);
652 /* 10.2.1.5.2 step 4.1 */
653 drbg_add_buf(drbg
->V
, drbg_blocklen(drbg
), &prefix
, 1);
654 drbg_string_fill(&data
, drbg
->V
, drbg_blocklen(drbg
));
655 while (len
< buflen
) {
657 /* 10.2.1.5.2 step 4.2 */
658 ret
= drbg_kcapi_sym(drbg
, drbg
->C
, drbg
->scratchpad
, &data
);
663 outlen
= (drbg_blocklen(drbg
) < (buflen
- len
)) ?
664 drbg_blocklen(drbg
) : (buflen
- len
);
665 if (!drbg_fips_continuous_test(drbg
, drbg
->scratchpad
)) {
666 /* 10.2.1.5.2 step 6 */
667 drbg_add_buf(drbg
->V
, drbg_blocklen(drbg
), &prefix
, 1);
670 /* 10.2.1.5.2 step 4.3 */
671 memcpy(buf
+ len
, drbg
->scratchpad
, outlen
);
673 /* 10.2.1.5.2 step 6 */
675 drbg_add_buf(drbg
->V
, drbg_blocklen(drbg
), &prefix
, 1);
680 * The following call invokes the DF function again which could be
681 * optimized. In step 2, the "additional_input" after step 2 is the
682 * output of the DF function. If this result would be saved, the DF
683 * function would not need to be invoked again at this point.
685 if (addtl
&& 0 < addtl
->len
) {
686 LIST_HEAD(addtllist
);
688 list_add_tail(&addtl
->list
, &addtllist
);
689 ret
= drbg_ctr_update(drbg
, &addtllist
, 1);
691 ret
= drbg_ctr_update(drbg
, NULL
, 1);
697 memset(drbg
->scratchpad
, 0, drbg_blocklen(drbg
));
701 static struct drbg_state_ops drbg_ctr_ops
= {
702 .update
= drbg_ctr_update
,
703 .generate
= drbg_ctr_generate
,
704 .crypto_init
= drbg_init_sym_kernel
,
705 .crypto_fini
= drbg_fini_sym_kernel
,
707 #endif /* CONFIG_CRYPTO_DRBG_CTR */
709 /******************************************************************
710 * HMAC DRBG callback functions
711 ******************************************************************/
713 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
714 static int drbg_kcapi_hash(struct drbg_state
*drbg
, const unsigned char *key
,
715 unsigned char *outval
, const struct list_head
*in
);
716 static int drbg_init_hash_kernel(struct drbg_state
*drbg
);
717 static int drbg_fini_hash_kernel(struct drbg_state
*drbg
);
718 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
720 #ifdef CONFIG_CRYPTO_DRBG_HMAC
721 #define CRYPTO_DRBG_HMAC_STRING "HMAC "
722 /* update function of HMAC DRBG as defined in 10.1.2.2 */
723 static int drbg_hmac_update(struct drbg_state
*drbg
, struct list_head
*seed
,
728 struct drbg_string seed1
, seed2
, vdata
;
730 LIST_HEAD(vdatalist
);
733 /* 10.1.2.3 step 2 */
734 memset(drbg
->C
, 0, drbg_statelen(drbg
));
735 memset(drbg
->V
, 1, drbg_statelen(drbg
));
738 drbg_string_fill(&seed1
, drbg
->V
, drbg_statelen(drbg
));
739 list_add_tail(&seed1
.list
, &seedlist
);
740 /* buffer of seed2 will be filled in for loop below with one byte */
741 drbg_string_fill(&seed2
, NULL
, 1);
742 list_add_tail(&seed2
.list
, &seedlist
);
743 /* input data of seed is allowed to be NULL at this point */
745 list_splice_tail(seed
, &seedlist
);
747 drbg_string_fill(&vdata
, drbg
->V
, drbg_statelen(drbg
));
748 list_add_tail(&vdata
.list
, &vdatalist
);
749 for (i
= 2; 0 < i
; i
--) {
750 /* first round uses 0x0, second 0x1 */
751 unsigned char prefix
= DRBG_PREFIX0
;
753 prefix
= DRBG_PREFIX1
;
754 /* 10.1.2.2 step 1 and 4 -- concatenation and HMAC for key */
756 ret
= drbg_kcapi_hash(drbg
, drbg
->C
, drbg
->C
, &seedlist
);
760 /* 10.1.2.2 step 2 and 5 -- HMAC for V */
761 ret
= drbg_kcapi_hash(drbg
, drbg
->C
, drbg
->V
, &vdatalist
);
765 /* 10.1.2.2 step 3 */
773 /* generate function of HMAC DRBG as defined in 10.1.2.5 */
774 static int drbg_hmac_generate(struct drbg_state
*drbg
,
777 struct drbg_string
*addtl
)
781 struct drbg_string data
;
784 /* 10.1.2.5 step 2 */
785 if (addtl
&& 0 < addtl
->len
) {
786 LIST_HEAD(addtllist
);
788 list_add_tail(&addtl
->list
, &addtllist
);
789 ret
= drbg_hmac_update(drbg
, &addtllist
, 1);
794 drbg_string_fill(&data
, drbg
->V
, drbg_statelen(drbg
));
795 list_add_tail(&data
.list
, &datalist
);
796 while (len
< buflen
) {
797 unsigned int outlen
= 0;
798 /* 10.1.2.5 step 4.1 */
799 ret
= drbg_kcapi_hash(drbg
, drbg
->C
, drbg
->V
, &datalist
);
802 outlen
= (drbg_blocklen(drbg
) < (buflen
- len
)) ?
803 drbg_blocklen(drbg
) : (buflen
- len
);
804 if (!drbg_fips_continuous_test(drbg
, drbg
->V
))
807 /* 10.1.2.5 step 4.2 */
808 memcpy(buf
+ len
, drbg
->V
, outlen
);
812 /* 10.1.2.5 step 6 */
813 if (addtl
&& 0 < addtl
->len
) {
814 LIST_HEAD(addtllist
);
816 list_add_tail(&addtl
->list
, &addtllist
);
817 ret
= drbg_hmac_update(drbg
, &addtllist
, 1);
819 ret
= drbg_hmac_update(drbg
, NULL
, 1);
827 static struct drbg_state_ops drbg_hmac_ops
= {
828 .update
= drbg_hmac_update
,
829 .generate
= drbg_hmac_generate
,
830 .crypto_init
= drbg_init_hash_kernel
,
831 .crypto_fini
= drbg_fini_hash_kernel
,
834 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
836 /******************************************************************
837 * Hash DRBG callback functions
838 ******************************************************************/
840 #ifdef CONFIG_CRYPTO_DRBG_HASH
841 #define CRYPTO_DRBG_HASH_STRING "HASH "
843 * scratchpad usage: as drbg_hash_update and drbg_hash_df are used
844 * interlinked, the scratchpad is used as follows:
846 * start: drbg->scratchpad
847 * length: drbg_statelen(drbg)
849 * start: drbg->scratchpad + drbg_statelen(drbg)
850 * length: drbg_blocklen(drbg)
852 * drbg_hash_process_addtl uses the scratchpad, but fully completes
853 * before either of the functions mentioned before are invoked. Therefore,
854 * drbg_hash_process_addtl does not need to be specifically considered.
857 /* Derivation Function for Hash DRBG as defined in 10.4.1 */
858 static int drbg_hash_df(struct drbg_state
*drbg
,
859 unsigned char *outval
, size_t outlen
,
860 struct list_head
*entropylist
)
864 unsigned char input
[5];
865 unsigned char *tmp
= drbg
->scratchpad
+ drbg_statelen(drbg
);
866 struct drbg_string data
;
868 memset(tmp
, 0, drbg_blocklen(drbg
));
872 drbg_int2byte(&input
[1], (outlen
* 8), 4);
874 /* 10.4.1 step 4.1 -- concatenation of data for input into hash */
875 drbg_string_fill(&data
, input
, 5);
876 list_add(&data
.list
, entropylist
);
879 while (len
< outlen
) {
881 /* 10.4.1 step 4.1 */
882 ret
= drbg_kcapi_hash(drbg
, NULL
, tmp
, entropylist
);
885 /* 10.4.1 step 4.2 */
887 blocklen
= (drbg_blocklen(drbg
) < (outlen
- len
)) ?
888 drbg_blocklen(drbg
) : (outlen
- len
);
889 memcpy(outval
+ len
, tmp
, blocklen
);
894 memset(tmp
, 0, drbg_blocklen(drbg
));
898 /* update function for Hash DRBG as defined in 10.1.1.2 / 10.1.1.3 */
899 static int drbg_hash_update(struct drbg_state
*drbg
, struct list_head
*seed
,
903 struct drbg_string data1
, data2
;
905 LIST_HEAD(datalist2
);
906 unsigned char *V
= drbg
->scratchpad
;
907 unsigned char prefix
= DRBG_PREFIX1
;
909 memset(drbg
->scratchpad
, 0, drbg_statelen(drbg
));
914 /* 10.1.1.3 step 1 */
915 memcpy(V
, drbg
->V
, drbg_statelen(drbg
));
916 drbg_string_fill(&data1
, &prefix
, 1);
917 list_add_tail(&data1
.list
, &datalist
);
918 drbg_string_fill(&data2
, V
, drbg_statelen(drbg
));
919 list_add_tail(&data2
.list
, &datalist
);
921 list_splice_tail(seed
, &datalist
);
923 /* 10.1.1.2 / 10.1.1.3 step 2 and 3 */
924 ret
= drbg_hash_df(drbg
, drbg
->V
, drbg_statelen(drbg
), &datalist
);
928 /* 10.1.1.2 / 10.1.1.3 step 4 */
929 prefix
= DRBG_PREFIX0
;
930 drbg_string_fill(&data1
, &prefix
, 1);
931 list_add_tail(&data1
.list
, &datalist2
);
932 drbg_string_fill(&data2
, drbg
->V
, drbg_statelen(drbg
));
933 list_add_tail(&data2
.list
, &datalist2
);
934 /* 10.1.1.2 / 10.1.1.3 step 4 */
935 ret
= drbg_hash_df(drbg
, drbg
->C
, drbg_statelen(drbg
), &datalist2
);
938 memset(drbg
->scratchpad
, 0, drbg_statelen(drbg
));
942 /* processing of additional information string for Hash DRBG */
943 static int drbg_hash_process_addtl(struct drbg_state
*drbg
,
944 struct drbg_string
*addtl
)
947 struct drbg_string data1
, data2
;
949 unsigned char prefix
= DRBG_PREFIX2
;
951 /* this is value w as per documentation */
952 memset(drbg
->scratchpad
, 0, drbg_blocklen(drbg
));
954 /* 10.1.1.4 step 2 */
955 if (!addtl
|| 0 == addtl
->len
)
958 /* 10.1.1.4 step 2a */
959 drbg_string_fill(&data1
, &prefix
, 1);
960 drbg_string_fill(&data2
, drbg
->V
, drbg_statelen(drbg
));
961 list_add_tail(&data1
.list
, &datalist
);
962 list_add_tail(&data2
.list
, &datalist
);
963 list_add_tail(&addtl
->list
, &datalist
);
964 ret
= drbg_kcapi_hash(drbg
, NULL
, drbg
->scratchpad
, &datalist
);
968 /* 10.1.1.4 step 2b */
969 drbg_add_buf(drbg
->V
, drbg_statelen(drbg
),
970 drbg
->scratchpad
, drbg_blocklen(drbg
));
973 memset(drbg
->scratchpad
, 0, drbg_blocklen(drbg
));
977 /* Hashgen defined in 10.1.1.4 */
978 static int drbg_hash_hashgen(struct drbg_state
*drbg
,
984 unsigned char *src
= drbg
->scratchpad
;
985 unsigned char *dst
= drbg
->scratchpad
+ drbg_statelen(drbg
);
986 struct drbg_string data
;
988 unsigned char prefix
= DRBG_PREFIX1
;
990 memset(src
, 0, drbg_statelen(drbg
));
991 memset(dst
, 0, drbg_blocklen(drbg
));
993 /* 10.1.1.4 step hashgen 2 */
994 memcpy(src
, drbg
->V
, drbg_statelen(drbg
));
996 drbg_string_fill(&data
, src
, drbg_statelen(drbg
));
997 list_add_tail(&data
.list
, &datalist
);
998 while (len
< buflen
) {
999 unsigned int outlen
= 0;
1000 /* 10.1.1.4 step hashgen 4.1 */
1001 ret
= drbg_kcapi_hash(drbg
, NULL
, dst
, &datalist
);
1006 outlen
= (drbg_blocklen(drbg
) < (buflen
- len
)) ?
1007 drbg_blocklen(drbg
) : (buflen
- len
);
1008 if (!drbg_fips_continuous_test(drbg
, dst
)) {
1009 drbg_add_buf(src
, drbg_statelen(drbg
), &prefix
, 1);
1012 /* 10.1.1.4 step hashgen 4.2 */
1013 memcpy(buf
+ len
, dst
, outlen
);
1015 /* 10.1.1.4 hashgen step 4.3 */
1017 drbg_add_buf(src
, drbg_statelen(drbg
), &prefix
, 1);
1021 memset(drbg
->scratchpad
, 0,
1022 (drbg_statelen(drbg
) + drbg_blocklen(drbg
)));
1026 /* generate function for Hash DRBG as defined in 10.1.1.4 */
1027 static int drbg_hash_generate(struct drbg_state
*drbg
,
1028 unsigned char *buf
, unsigned int buflen
,
1029 struct drbg_string
*addtl
)
1033 unsigned char req
[8];
1034 unsigned char prefix
= DRBG_PREFIX3
;
1035 struct drbg_string data1
, data2
;
1036 LIST_HEAD(datalist
);
1038 /* 10.1.1.4 step 2 */
1039 ret
= drbg_hash_process_addtl(drbg
, addtl
);
1042 /* 10.1.1.4 step 3 */
1043 len
= drbg_hash_hashgen(drbg
, buf
, buflen
);
1045 /* this is the value H as documented in 10.1.1.4 */
1046 memset(drbg
->scratchpad
, 0, drbg_blocklen(drbg
));
1047 /* 10.1.1.4 step 4 */
1048 drbg_string_fill(&data1
, &prefix
, 1);
1049 list_add_tail(&data1
.list
, &datalist
);
1050 drbg_string_fill(&data2
, drbg
->V
, drbg_statelen(drbg
));
1051 list_add_tail(&data2
.list
, &datalist
);
1052 ret
= drbg_kcapi_hash(drbg
, NULL
, drbg
->scratchpad
, &datalist
);
1058 /* 10.1.1.4 step 5 */
1059 drbg_add_buf(drbg
->V
, drbg_statelen(drbg
),
1060 drbg
->scratchpad
, drbg_blocklen(drbg
));
1061 drbg_add_buf(drbg
->V
, drbg_statelen(drbg
),
1062 drbg
->C
, drbg_statelen(drbg
));
1063 drbg_int2byte(req
, drbg
->reseed_ctr
, sizeof(req
));
1064 drbg_add_buf(drbg
->V
, drbg_statelen(drbg
), req
, 8);
1067 memset(drbg
->scratchpad
, 0, drbg_blocklen(drbg
));
1072 * scratchpad usage: as update and generate are used isolated, both
1073 * can use the scratchpad
1075 static struct drbg_state_ops drbg_hash_ops
= {
1076 .update
= drbg_hash_update
,
1077 .generate
= drbg_hash_generate
,
1078 .crypto_init
= drbg_init_hash_kernel
,
1079 .crypto_fini
= drbg_fini_hash_kernel
,
1081 #endif /* CONFIG_CRYPTO_DRBG_HASH */
1083 /******************************************************************
1084 * Functions common for DRBG implementations
1085 ******************************************************************/
1088 * Seeding or reseeding of the DRBG
1090 * @drbg: DRBG state struct
1091 * @pers: personalization / additional information buffer
1092 * @reseed: 0 for initial seed process, 1 for reseeding
1096 * error value otherwise
1098 static int drbg_seed(struct drbg_state
*drbg
, struct drbg_string
*pers
,
1102 unsigned char *entropy
= NULL
;
1103 size_t entropylen
= 0;
1104 struct drbg_string data1
;
1105 LIST_HEAD(seedlist
);
1107 /* 9.1 / 9.2 / 9.3.1 step 3 */
1108 if (pers
&& pers
->len
> (drbg_max_addtl(drbg
))) {
1109 pr_devel("DRBG: personalization string too long %zu\n",
1114 if (drbg
->test_data
&& drbg
->test_data
->testentropy
) {
1115 drbg_string_fill(&data1
, drbg
->test_data
->testentropy
->buf
,
1116 drbg
->test_data
->testentropy
->len
);
1117 pr_devel("DRBG: using test entropy\n");
1120 * Gather entropy equal to the security strength of the DRBG.
1121 * With a derivation function, a nonce is required in addition
1122 * to the entropy. A nonce must be at least 1/2 of the security
1123 * strength of the DRBG in size. Thus, entropy * nonce is 3/2
1124 * of the strength. The consideration of a nonce is only
1125 * applicable during initial seeding.
1127 entropylen
= drbg_sec_strength(drbg
->core
->flags
);
1131 entropylen
= ((entropylen
+ 1) / 2) * 3;
1132 pr_devel("DRBG: (re)seeding with %zu bytes of entropy\n",
1134 entropy
= kzalloc(entropylen
, GFP_KERNEL
);
1137 get_random_bytes(entropy
, entropylen
);
1138 drbg_string_fill(&data1
, entropy
, entropylen
);
1140 list_add_tail(&data1
.list
, &seedlist
);
1143 * concatenation of entropy with personalization str / addtl input)
1144 * the variable pers is directly handed in by the caller, so check its
1145 * contents whether it is appropriate
1147 if (pers
&& pers
->buf
&& 0 < pers
->len
) {
1148 list_add_tail(&pers
->list
, &seedlist
);
1149 pr_devel("DRBG: using personalization string\n");
1152 ret
= drbg
->d_ops
->update(drbg
, &seedlist
, reseed
);
1156 drbg
->seeded
= true;
1157 /* 10.1.1.2 / 10.1.1.3 step 5 */
1158 drbg
->reseed_ctr
= 1;
1166 /* Free all substructures in a DRBG state without the DRBG state structure */
1167 static inline void drbg_dealloc_state(struct drbg_state
*drbg
)
1177 if (drbg
->scratchpad
)
1178 kzfree(drbg
->scratchpad
);
1179 drbg
->scratchpad
= NULL
;
1180 drbg
->reseed_ctr
= 0;
1181 #ifdef CONFIG_CRYPTO_FIPS
1185 drbg
->fips_primed
= false;
1190 * Allocate all sub-structures for a DRBG state.
1191 * The DRBG state structure must already be allocated.
1193 static inline int drbg_alloc_state(struct drbg_state
*drbg
)
1196 unsigned int sb_size
= 0;
1201 drbg
->V
= kzalloc(drbg_statelen(drbg
), GFP_KERNEL
);
1204 drbg
->C
= kzalloc(drbg_statelen(drbg
), GFP_KERNEL
);
1207 #ifdef CONFIG_CRYPTO_FIPS
1208 drbg
->prev
= kzalloc(drbg_blocklen(drbg
), GFP_KERNEL
);
1211 drbg
->fips_primed
= false;
1213 /* scratchpad is only generated for CTR and Hash */
1214 if (drbg
->core
->flags
& DRBG_HMAC
)
1216 else if (drbg
->core
->flags
& DRBG_CTR
)
1217 sb_size
= drbg_statelen(drbg
) + drbg_blocklen(drbg
) + /* temp */
1218 drbg_statelen(drbg
) + /* df_data */
1219 drbg_blocklen(drbg
) + /* pad */
1220 drbg_blocklen(drbg
) + /* iv */
1221 drbg_statelen(drbg
) + drbg_blocklen(drbg
); /* temp */
1223 sb_size
= drbg_statelen(drbg
) + drbg_blocklen(drbg
);
1226 drbg
->scratchpad
= kzalloc(sb_size
, GFP_KERNEL
);
1227 if (!drbg
->scratchpad
)
1230 spin_lock_init(&drbg
->drbg_lock
);
1234 drbg_dealloc_state(drbg
);
1239 * Strategy to avoid holding long term locks: generate a shadow copy of DRBG
1240 * and perform all operations on this shadow copy. After finishing, restore
1241 * the updated state of the shadow copy into original drbg state. This way,
1242 * only the read and write operations of the original drbg state must be
1245 static inline void drbg_copy_drbg(struct drbg_state
*src
,
1246 struct drbg_state
*dst
)
1250 memcpy(dst
->V
, src
->V
, drbg_statelen(src
));
1251 memcpy(dst
->C
, src
->C
, drbg_statelen(src
));
1252 dst
->reseed_ctr
= src
->reseed_ctr
;
1253 dst
->seeded
= src
->seeded
;
1255 #ifdef CONFIG_CRYPTO_FIPS
1256 dst
->fips_primed
= src
->fips_primed
;
1257 memcpy(dst
->prev
, src
->prev
, drbg_blocklen(src
));
1261 * scratchpad is initialized drbg_alloc_state;
1262 * priv_data is initialized with call to crypto_init;
1263 * d_ops and core are set outside, as these parameters are const;
1264 * test_data is set outside to prevent it being copied back.
1268 static int drbg_make_shadow(struct drbg_state
*drbg
, struct drbg_state
**shadow
)
1271 struct drbg_state
*tmp
= NULL
;
1273 if (!drbg
|| !drbg
->core
|| !drbg
->V
|| !drbg
->C
) {
1274 pr_devel("DRBG: attempt to generate shadow copy for "
1275 "uninitialized DRBG state rejected\n");
1278 /* HMAC does not have a scratchpad */
1279 if (!(drbg
->core
->flags
& DRBG_HMAC
) && NULL
== drbg
->scratchpad
)
1282 tmp
= kzalloc(sizeof(struct drbg_state
), GFP_KERNEL
);
1286 /* read-only data as they are defined as const, no lock needed */
1287 tmp
->core
= drbg
->core
;
1288 tmp
->d_ops
= drbg
->d_ops
;
1290 ret
= drbg_alloc_state(tmp
);
1294 spin_lock_bh(&drbg
->drbg_lock
);
1295 drbg_copy_drbg(drbg
, tmp
);
1296 /* only make a link to the test buffer, as we only read that data */
1297 tmp
->test_data
= drbg
->test_data
;
1298 spin_unlock_bh(&drbg
->drbg_lock
);
1308 static void drbg_restore_shadow(struct drbg_state
*drbg
,
1309 struct drbg_state
**shadow
)
1311 struct drbg_state
*tmp
= *shadow
;
1313 spin_lock_bh(&drbg
->drbg_lock
);
1314 drbg_copy_drbg(tmp
, drbg
);
1315 spin_unlock_bh(&drbg
->drbg_lock
);
1316 drbg_dealloc_state(tmp
);
1321 /*************************************************************************
1322 * DRBG interface functions
1323 *************************************************************************/
1326 * DRBG generate function as required by SP800-90A - this function
1327 * generates random numbers
1329 * @drbg DRBG state handle
1330 * @buf Buffer where to store the random numbers -- the buffer must already
1331 * be pre-allocated by caller
1332 * @buflen Length of output buffer - this value defines the number of random
1333 * bytes pulled from DRBG
1334 * @addtl Additional input that is mixed into state, may be NULL -- note
1335 * the entropy is pulled by the DRBG internally unconditionally
1336 * as defined in SP800-90A. The additional input is mixed into
1337 * the state in addition to the pulled entropy.
1339 * return: generated number of bytes
1341 static int drbg_generate(struct drbg_state
*drbg
,
1342 unsigned char *buf
, unsigned int buflen
,
1343 struct drbg_string
*addtl
)
1346 struct drbg_state
*shadow
= NULL
;
1348 if (0 == buflen
|| !buf
) {
1349 pr_devel("DRBG: no output buffer provided\n");
1352 if (addtl
&& NULL
== addtl
->buf
&& 0 < addtl
->len
) {
1353 pr_devel("DRBG: wrong format of additional information\n");
1357 len
= drbg_make_shadow(drbg
, &shadow
);
1359 pr_devel("DRBG: shadow copy cannot be generated\n");
1365 if (buflen
> (drbg_max_request_bytes(shadow
))) {
1366 pr_devel("DRBG: requested random numbers too large %u\n",
1371 /* 9.3.1 step 3 is implicit with the chosen DRBG */
1374 if (addtl
&& addtl
->len
> (drbg_max_addtl(shadow
))) {
1375 pr_devel("DRBG: additional information string too long %zu\n",
1379 /* 9.3.1 step 5 is implicit with the chosen DRBG */
1382 * 9.3.1 step 6 and 9 supplemented by 9.3.2 step c is implemented
1383 * here. The spec is a bit convoluted here, we make it simpler.
1385 if ((drbg_max_requests(shadow
)) < shadow
->reseed_ctr
)
1386 shadow
->seeded
= false;
1388 /* allocate cipher handle */
1389 if (shadow
->d_ops
->crypto_init
) {
1390 len
= shadow
->d_ops
->crypto_init(shadow
);
1395 if (shadow
->pr
|| !shadow
->seeded
) {
1396 pr_devel("DRBG: reseeding before generation (prediction "
1397 "resistance: %s, state %s)\n",
1398 drbg
->pr
? "true" : "false",
1399 drbg
->seeded
? "seeded" : "unseeded");
1400 /* 9.3.1 steps 7.1 through 7.3 */
1401 len
= drbg_seed(shadow
, addtl
, true);
1404 /* 9.3.1 step 7.4 */
1407 /* 9.3.1 step 8 and 10 */
1408 len
= shadow
->d_ops
->generate(shadow
, buf
, buflen
, addtl
);
1410 /* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */
1411 shadow
->reseed_ctr
++;
1416 * Section 11.3.3 requires to re-perform self tests after some
1417 * generated random numbers. The chosen value after which self
1418 * test is performed is arbitrary, but it should be reasonable.
1419 * However, we do not perform the self tests because of the following
1420 * reasons: it is mathematically impossible that the initial self tests
1421 * were successfully and the following are not. If the initial would
1422 * pass and the following would not, the kernel integrity is violated.
1423 * In this case, the entire kernel operation is questionable and it
1424 * is unlikely that the integrity violation only affects the
1425 * correct operation of the DRBG.
1427 * Albeit the following code is commented out, it is provided in
1428 * case somebody has a need to implement the test of 11.3.3.
1431 if (shadow
->reseed_ctr
&& !(shadow
->reseed_ctr
% 4096)) {
1433 pr_devel("DRBG: start to perform self test\n");
1434 if (drbg
->core
->flags
& DRBG_HMAC
)
1435 err
= alg_test("drbg_pr_hmac_sha256",
1436 "drbg_pr_hmac_sha256", 0, 0);
1437 else if (drbg
->core
->flags
& DRBG_CTR
)
1438 err
= alg_test("drbg_pr_ctr_aes128",
1439 "drbg_pr_ctr_aes128", 0, 0);
1441 err
= alg_test("drbg_pr_sha256",
1442 "drbg_pr_sha256", 0, 0);
1444 pr_err("DRBG: periodical self test failed\n");
1446 * uninstantiate implies that from now on, only errors
1447 * are returned when reusing this DRBG cipher handle
1449 drbg_uninstantiate(drbg
);
1450 drbg_dealloc_state(shadow
);
1454 pr_devel("DRBG: self test successful\n");
1460 if (shadow
->d_ops
->crypto_fini
)
1461 shadow
->d_ops
->crypto_fini(shadow
);
1462 drbg_restore_shadow(drbg
, &shadow
);
1467 * Wrapper around drbg_generate which can pull arbitrary long strings
1468 * from the DRBG without hitting the maximum request limitation.
1470 * Parameters: see drbg_generate
1471 * Return codes: see drbg_generate -- if one drbg_generate request fails,
1472 * the entire drbg_generate_long request fails
1474 static int drbg_generate_long(struct drbg_state
*drbg
,
1475 unsigned char *buf
, unsigned int buflen
,
1476 struct drbg_string
*addtl
)
1479 unsigned int slice
= 0;
1482 unsigned int chunk
= 0;
1483 slice
= ((buflen
- len
) / drbg_max_request_bytes(drbg
));
1484 chunk
= slice
? drbg_max_request_bytes(drbg
) : (buflen
- len
);
1485 tmplen
= drbg_generate(drbg
, buf
+ len
, chunk
, addtl
);
1489 } while (slice
> 0);
1494 * DRBG instantiation function as required by SP800-90A - this function
1495 * sets up the DRBG handle, performs the initial seeding and all sanity
1496 * checks required by SP800-90A
1498 * @drbg memory of state -- if NULL, new memory is allocated
1499 * @pers Personalization string that is mixed into state, may be NULL -- note
1500 * the entropy is pulled by the DRBG internally unconditionally
1501 * as defined in SP800-90A. The additional input is mixed into
1502 * the state in addition to the pulled entropy.
1503 * @coreref reference to core
1504 * @pr prediction resistance enabled
1508 * error value otherwise
1510 static int drbg_instantiate(struct drbg_state
*drbg
, struct drbg_string
*pers
,
1511 int coreref
, bool pr
)
1515 pr_devel("DRBG: Initializing DRBG core %d with prediction resistance "
1516 "%s\n", coreref
, pr
? "enabled" : "disabled");
1517 drbg
->core
= &drbg_cores
[coreref
];
1519 drbg
->seeded
= false;
1520 switch (drbg
->core
->flags
& DRBG_TYPE_MASK
) {
1521 #ifdef CONFIG_CRYPTO_DRBG_HMAC
1523 drbg
->d_ops
= &drbg_hmac_ops
;
1525 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
1526 #ifdef CONFIG_CRYPTO_DRBG_HASH
1528 drbg
->d_ops
= &drbg_hash_ops
;
1530 #endif /* CONFIG_CRYPTO_DRBG_HASH */
1531 #ifdef CONFIG_CRYPTO_DRBG_CTR
1533 drbg
->d_ops
= &drbg_ctr_ops
;
1535 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1540 /* 9.1 step 1 is implicit with the selected DRBG type */
1543 * 9.1 step 2 is implicit as caller can select prediction resistance
1544 * and the flag is copied into drbg->flags --
1545 * all DRBG types support prediction resistance
1548 /* 9.1 step 4 is implicit in drbg_sec_strength */
1550 ret
= drbg_alloc_state(drbg
);
1555 if (drbg
->d_ops
->crypto_init
&& drbg
->d_ops
->crypto_init(drbg
))
1557 ret
= drbg_seed(drbg
, pers
, false);
1558 if (drbg
->d_ops
->crypto_fini
)
1559 drbg
->d_ops
->crypto_fini(drbg
);
1566 drbg_dealloc_state(drbg
);
1571 * DRBG uninstantiate function as required by SP800-90A - this function
1572 * frees all buffers and the DRBG handle
1574 * @drbg DRBG state handle
1579 static int drbg_uninstantiate(struct drbg_state
*drbg
)
1581 spin_lock_bh(&drbg
->drbg_lock
);
1582 drbg_dealloc_state(drbg
);
1583 /* no scrubbing of test_data -- this shall survive an uninstantiate */
1584 spin_unlock_bh(&drbg
->drbg_lock
);
1589 * Helper function for setting the test data in the DRBG
1591 * @drbg DRBG state handle
1592 * @test_data test data to sets
1594 static inline void drbg_set_testdata(struct drbg_state
*drbg
,
1595 struct drbg_test_data
*test_data
)
1597 if (!test_data
|| !test_data
->testentropy
)
1599 spin_lock_bh(&drbg
->drbg_lock
);
1600 drbg
->test_data
= test_data
;
1601 spin_unlock_bh(&drbg
->drbg_lock
);
1604 /***************************************************************
1605 * Kernel crypto API cipher invocations requested by DRBG
1606 ***************************************************************/
1608 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
1610 struct shash_desc shash
;
1614 static int drbg_init_hash_kernel(struct drbg_state
*drbg
)
1616 struct sdesc
*sdesc
;
1617 struct crypto_shash
*tfm
;
1619 tfm
= crypto_alloc_shash(drbg
->core
->backend_cra_name
, 0, 0);
1621 pr_info("DRBG: could not allocate digest TFM handle\n");
1622 return PTR_ERR(tfm
);
1624 BUG_ON(drbg_blocklen(drbg
) != crypto_shash_digestsize(tfm
));
1625 sdesc
= kzalloc(sizeof(struct shash_desc
) + crypto_shash_descsize(tfm
),
1628 crypto_free_shash(tfm
);
1632 sdesc
->shash
.tfm
= tfm
;
1633 sdesc
->shash
.flags
= 0;
1634 drbg
->priv_data
= sdesc
;
1638 static int drbg_fini_hash_kernel(struct drbg_state
*drbg
)
1640 struct sdesc
*sdesc
= (struct sdesc
*)drbg
->priv_data
;
1642 crypto_free_shash(sdesc
->shash
.tfm
);
1645 drbg
->priv_data
= NULL
;
1649 static int drbg_kcapi_hash(struct drbg_state
*drbg
, const unsigned char *key
,
1650 unsigned char *outval
, const struct list_head
*in
)
1652 struct sdesc
*sdesc
= (struct sdesc
*)drbg
->priv_data
;
1653 struct drbg_string
*input
= NULL
;
1656 crypto_shash_setkey(sdesc
->shash
.tfm
, key
, drbg_statelen(drbg
));
1657 crypto_shash_init(&sdesc
->shash
);
1658 list_for_each_entry(input
, in
, list
)
1659 crypto_shash_update(&sdesc
->shash
, input
->buf
, input
->len
);
1660 return crypto_shash_final(&sdesc
->shash
, outval
);
1662 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
1664 #ifdef CONFIG_CRYPTO_DRBG_CTR
1665 static int drbg_init_sym_kernel(struct drbg_state
*drbg
)
1668 struct crypto_blkcipher
*tfm
;
1670 tfm
= crypto_alloc_blkcipher(drbg
->core
->backend_cra_name
, 0, 0);
1672 pr_info("DRBG: could not allocate cipher TFM handle\n");
1673 return PTR_ERR(tfm
);
1675 BUG_ON(drbg_blocklen(drbg
) != crypto_blkcipher_blocksize(tfm
));
1676 drbg
->priv_data
= tfm
;
1680 static int drbg_fini_sym_kernel(struct drbg_state
*drbg
)
1682 struct crypto_blkcipher
*tfm
=
1683 (struct crypto_blkcipher
*)drbg
->priv_data
;
1685 crypto_free_blkcipher(tfm
);
1686 drbg
->priv_data
= NULL
;
1690 static int drbg_kcapi_sym(struct drbg_state
*drbg
, const unsigned char *key
,
1691 unsigned char *outval
, const struct drbg_string
*in
)
1694 struct scatterlist sg_in
, sg_out
;
1695 struct blkcipher_desc desc
;
1696 struct crypto_blkcipher
*tfm
=
1697 (struct crypto_blkcipher
*)drbg
->priv_data
;
1701 crypto_blkcipher_setkey(tfm
, key
, (drbg_keylen(drbg
)));
1702 /* there is only component in *in */
1703 sg_init_one(&sg_in
, in
->buf
, in
->len
);
1704 sg_init_one(&sg_out
, outval
, drbg_blocklen(drbg
));
1705 ret
= crypto_blkcipher_encrypt(&desc
, &sg_out
, &sg_in
, in
->len
);
1709 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1711 /***************************************************************
1712 * Kernel crypto API interface to register DRBG
1713 ***************************************************************/
1716 * Look up the DRBG flags by given kernel crypto API cra_name
1717 * The code uses the drbg_cores definition to do this
1719 * @cra_name kernel crypto API cra_name
1720 * @coreref reference to integer which is filled with the pointer to
1721 * the applicable core
1722 * @pr reference for setting prediction resistance
1726 static inline void drbg_convert_tfm_core(const char *cra_driver_name
,
1727 int *coreref
, bool *pr
)
1734 /* disassemble the names */
1735 if (!memcmp(cra_driver_name
, "drbg_nopr_", 10)) {
1738 } else if (!memcmp(cra_driver_name
, "drbg_pr_", 8)) {
1744 /* remove the first part */
1745 len
= strlen(cra_driver_name
) - start
;
1746 for (i
= 0; ARRAY_SIZE(drbg_cores
) > i
; i
++) {
1747 if (!memcmp(cra_driver_name
+ start
, drbg_cores
[i
].cra_name
,
1755 static int drbg_kcapi_init(struct crypto_tfm
*tfm
)
1757 struct drbg_state
*drbg
= crypto_tfm_ctx(tfm
);
1761 drbg_convert_tfm_core(crypto_tfm_alg_name(tfm
), &coreref
, &pr
);
1763 * when personalization string is needed, the caller must call reset
1764 * and provide the personalization string as seed information
1766 return drbg_instantiate(drbg
, NULL
, coreref
, pr
);
1769 static void drbg_kcapi_cleanup(struct crypto_tfm
*tfm
)
1771 drbg_uninstantiate(crypto_tfm_ctx(tfm
));
1775 * Generate random numbers invoked by the kernel crypto API:
1776 * The API of the kernel crypto API is extended as follows:
1778 * If dlen is larger than zero, rdata is interpreted as the output buffer
1779 * where random data is to be stored.
1781 * If dlen is zero, rdata is interpreted as a pointer to a struct drbg_gen
1782 * which holds the additional information string that is used for the
1783 * DRBG generation process. The output buffer that is to be used to store
1784 * data is also pointed to by struct drbg_gen.
1786 static int drbg_kcapi_random(struct crypto_rng
*tfm
, u8
*rdata
,
1789 struct drbg_state
*drbg
= crypto_rng_ctx(tfm
);
1791 return drbg_generate_long(drbg
, rdata
, dlen
, NULL
);
1793 struct drbg_gen
*data
= (struct drbg_gen
*)rdata
;
1794 struct drbg_string addtl
;
1795 /* catch NULL pointer */
1798 drbg_set_testdata(drbg
, data
->test_data
);
1799 /* linked list variable is now local to allow modification */
1800 drbg_string_fill(&addtl
, data
->addtl
->buf
, data
->addtl
->len
);
1801 return drbg_generate_long(drbg
, data
->outbuf
, data
->outlen
,
1807 * Reset the DRBG invoked by the kernel crypto API
1808 * The reset implies a full re-initialization of the DRBG. Similar to the
1809 * generate function of drbg_kcapi_random, this function extends the
1810 * kernel crypto API interface with struct drbg_gen
1812 static int drbg_kcapi_reset(struct crypto_rng
*tfm
, u8
*seed
, unsigned int slen
)
1814 struct drbg_state
*drbg
= crypto_rng_ctx(tfm
);
1815 struct crypto_tfm
*tfm_base
= crypto_rng_tfm(tfm
);
1817 struct drbg_string seed_string
;
1820 drbg_uninstantiate(drbg
);
1821 drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base
), &coreref
,
1824 drbg_string_fill(&seed_string
, seed
, slen
);
1825 return drbg_instantiate(drbg
, &seed_string
, coreref
, pr
);
1827 struct drbg_gen
*data
= (struct drbg_gen
*)seed
;
1828 /* allow invocation of API call with NULL, 0 */
1830 return drbg_instantiate(drbg
, NULL
, coreref
, pr
);
1831 drbg_set_testdata(drbg
, data
->test_data
);
1832 /* linked list variable is now local to allow modification */
1833 drbg_string_fill(&seed_string
, data
->addtl
->buf
,
1835 return drbg_instantiate(drbg
, &seed_string
, coreref
, pr
);
1839 /***************************************************************
1840 * Kernel module: code to load the module
1841 ***************************************************************/
1844 * Tests as defined in 11.3.2 in addition to the cipher tests: testing
1845 * of the error handling.
1847 * Note: testing of failing seed source as defined in 11.3.2 is not applicable
1848 * as seed source of get_random_bytes does not fail.
1850 * Note 2: There is no sensible way of testing the reseed counter
1851 * enforcement, so skip it.
1853 static inline int __init
drbg_healthcheck_sanity(void)
1855 #ifdef CONFIG_CRYPTO_FIPS
1857 #define OUTBUFLEN 16
1858 unsigned char buf
[OUTBUFLEN
];
1859 struct drbg_state
*drbg
= NULL
;
1864 struct drbg_string addtl
;
1865 size_t max_addtllen
, max_request_bytes
;
1867 /* only perform test in FIPS mode */
1871 #ifdef CONFIG_CRYPTO_DRBG_CTR
1872 drbg_convert_tfm_core("drbg_nopr_ctr_aes128", &coreref
, &pr
);
1873 #elif defined CONFIG_CRYPTO_DRBG_HASH
1874 drbg_convert_tfm_core("drbg_nopr_sha256", &coreref
, &pr
);
1876 drbg_convert_tfm_core("drbg_nopr_hmac_sha256", &coreref
, &pr
);
1879 drbg
= kzalloc(sizeof(struct drbg_state
), GFP_KERNEL
);
1884 * if the following tests fail, it is likely that there is a buffer
1885 * overflow as buf is much smaller than the requested or provided
1886 * string lengths -- in case the error handling does not succeed
1887 * we may get an OOPS. And we want to get an OOPS as this is a
1891 /* get a valid instance of DRBG for following tests */
1892 ret
= drbg_instantiate(drbg
, NULL
, coreref
, pr
);
1897 max_addtllen
= drbg_max_addtl(drbg
);
1898 max_request_bytes
= drbg_max_request_bytes(drbg
);
1899 drbg_string_fill(&addtl
, buf
, max_addtllen
+ 1);
1900 /* overflow addtllen with additonal info string */
1901 len
= drbg_generate(drbg
, buf
, OUTBUFLEN
, &addtl
);
1903 /* overflow max_bits */
1904 len
= drbg_generate(drbg
, buf
, (max_request_bytes
+ 1), NULL
);
1906 drbg_uninstantiate(drbg
);
1908 /* overflow max addtllen with personalization string */
1909 ret
= drbg_instantiate(drbg
, &addtl
, coreref
, pr
);
1911 /* test uninstantated DRBG */
1912 len
= drbg_generate(drbg
, buf
, (max_request_bytes
+ 1), NULL
);
1914 /* all tests passed */
1917 pr_devel("DRBG: Sanity tests for failure code paths successfully "
1920 drbg_uninstantiate(drbg
);
1924 #else /* CONFIG_CRYPTO_FIPS */
1926 #endif /* CONFIG_CRYPTO_FIPS */
1929 static struct crypto_alg drbg_algs
[22];
1932 * Fill the array drbg_algs used to register the different DRBGs
1933 * with the kernel crypto API. To fill the array, the information
1934 * from drbg_cores[] is used.
1936 static inline void __init
drbg_fill_array(struct crypto_alg
*alg
,
1937 const struct drbg_core
*core
, int pr
)
1940 static int priority
= 100;
1942 memset(alg
, 0, sizeof(struct crypto_alg
));
1943 memcpy(alg
->cra_name
, "stdrng", 6);
1945 memcpy(alg
->cra_driver_name
, "drbg_pr_", 8);
1948 memcpy(alg
->cra_driver_name
, "drbg_nopr_", 10);
1951 memcpy(alg
->cra_driver_name
+ pos
, core
->cra_name
,
1952 strlen(core
->cra_name
));
1954 alg
->cra_priority
= priority
;
1957 * If FIPS mode enabled, the selected DRBG shall have the
1958 * highest cra_priority over other stdrng instances to ensure
1962 alg
->cra_priority
+= 200;
1964 alg
->cra_flags
= CRYPTO_ALG_TYPE_RNG
;
1965 alg
->cra_ctxsize
= sizeof(struct drbg_state
);
1966 alg
->cra_type
= &crypto_rng_type
;
1967 alg
->cra_module
= THIS_MODULE
;
1968 alg
->cra_init
= drbg_kcapi_init
;
1969 alg
->cra_exit
= drbg_kcapi_cleanup
;
1970 alg
->cra_u
.rng
.rng_make_random
= drbg_kcapi_random
;
1971 alg
->cra_u
.rng
.rng_reset
= drbg_kcapi_reset
;
1972 alg
->cra_u
.rng
.seedsize
= 0;
1975 static int __init
drbg_init(void)
1977 unsigned int i
= 0; /* pointer to drbg_algs */
1978 unsigned int j
= 0; /* pointer to drbg_cores */
1981 ret
= drbg_healthcheck_sanity();
1985 if (ARRAY_SIZE(drbg_cores
) * 2 > ARRAY_SIZE(drbg_algs
)) {
1986 pr_info("DRBG: Cannot register all DRBG types"
1987 "(slots needed: %zu, slots available: %zu)\n",
1988 ARRAY_SIZE(drbg_cores
) * 2, ARRAY_SIZE(drbg_algs
));
1993 * each DRBG definition can be used with PR and without PR, thus
1994 * we instantiate each DRBG in drbg_cores[] twice.
1996 * As the order of placing them into the drbg_algs array matters
1997 * (the later DRBGs receive a higher cra_priority) we register the
1998 * prediction resistance DRBGs first as the should not be too
2001 for (j
= 0; ARRAY_SIZE(drbg_cores
) > j
; j
++, i
++)
2002 drbg_fill_array(&drbg_algs
[i
], &drbg_cores
[j
], 1);
2003 for (j
= 0; ARRAY_SIZE(drbg_cores
) > j
; j
++, i
++)
2004 drbg_fill_array(&drbg_algs
[i
], &drbg_cores
[j
], 0);
2005 return crypto_register_algs(drbg_algs
, (ARRAY_SIZE(drbg_cores
) * 2));
2008 void __exit
drbg_exit(void)
2010 crypto_unregister_algs(drbg_algs
, (ARRAY_SIZE(drbg_cores
) * 2));
2013 module_init(drbg_init
);
2014 module_exit(drbg_exit
);
2015 #ifndef CRYPTO_DRBG_HASH_STRING
2016 #define CRYPTO_DRBG_HASH_STRING ""
2018 #ifndef CRYPTO_DRBG_HMAC_STRING
2019 #define CRYPTO_DRBG_HMAC_STRING ""
2021 #ifndef CRYPTO_DRBG_CTR_STRING
2022 #define CRYPTO_DRBG_CTR_STRING ""
2024 MODULE_LICENSE("GPL");
2025 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
2026 MODULE_DESCRIPTION("NIST SP800-90A Deterministic Random Bit Generator (DRBG) "
2027 "using following cores: "
2028 CRYPTO_DRBG_HASH_STRING
2029 CRYPTO_DRBG_HMAC_STRING
2030 CRYPTO_DRBG_CTR_STRING
);