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 static int drbg_kcapi_sym(struct drbg_state
*drbg
, const unsigned char *key
,
360 unsigned char *outval
, const struct drbg_string
*in
);
361 static int drbg_init_sym_kernel(struct drbg_state
*drbg
);
362 static int drbg_fini_sym_kernel(struct drbg_state
*drbg
);
364 /* BCC function for CTR DRBG as defined in 10.4.3 */
365 static int drbg_ctr_bcc(struct drbg_state
*drbg
,
366 unsigned char *out
, const unsigned char *key
,
367 struct list_head
*in
)
370 struct drbg_string
*curr
= NULL
;
371 struct drbg_string data
;
374 drbg_string_fill(&data
, out
, drbg_blocklen(drbg
));
377 memset(out
, 0, drbg_blocklen(drbg
));
379 /* 10.4.3 step 2 / 4 */
380 list_for_each_entry(curr
, in
, list
) {
381 const unsigned char *pos
= curr
->buf
;
382 size_t len
= curr
->len
;
383 /* 10.4.3 step 4.1 */
385 /* 10.4.3 step 4.2 */
386 if (drbg_blocklen(drbg
) == cnt
) {
388 ret
= drbg_kcapi_sym(drbg
, key
, out
, &data
);
398 /* 10.4.3 step 4.2 for last block */
400 ret
= drbg_kcapi_sym(drbg
, key
, out
, &data
);
406 * scratchpad usage: drbg_ctr_update is interlinked with drbg_ctr_df
407 * (and drbg_ctr_bcc, but this function does not need any temporary buffers),
408 * the scratchpad is used as follows:
411 * start: drbg->scratchpad
412 * length: drbg_statelen(drbg) + drbg_blocklen(drbg)
413 * note: the cipher writing into this variable works
414 * blocklen-wise. Now, when the statelen is not a multiple
415 * of blocklen, the generateion loop below "spills over"
416 * by at most blocklen. Thus, we need to give sufficient
419 * start: drbg->scratchpad +
420 * drbg_statelen(drbg) + drbg_blocklen(drbg)
421 * length: drbg_statelen(drbg)
425 * start: df_data + drbg_statelen(drbg)
426 * length: drbg_blocklen(drbg)
428 * start: pad + drbg_blocklen(drbg)
429 * length: drbg_blocklen(drbg)
431 * start: iv + drbg_blocklen(drbg)
432 * length: drbg_satelen(drbg) + drbg_blocklen(drbg)
433 * note: temp is the buffer that the BCC function operates
434 * on. BCC operates blockwise. drbg_statelen(drbg)
435 * is sufficient when the DRBG state length is a multiple
436 * of the block size. For AES192 (and maybe other ciphers)
437 * this is not correct and the length for temp is
438 * insufficient (yes, that also means for such ciphers,
439 * the final output of all BCC rounds are truncated).
440 * Therefore, add drbg_blocklen(drbg) to cover all
444 /* Derivation Function for CTR DRBG as defined in 10.4.2 */
445 static int drbg_ctr_df(struct drbg_state
*drbg
,
446 unsigned char *df_data
, size_t bytes_to_return
,
447 struct list_head
*seedlist
)
450 unsigned char L_N
[8];
452 struct drbg_string S1
, S2
, S4
, cipherin
;
454 unsigned char *pad
= df_data
+ drbg_statelen(drbg
);
455 unsigned char *iv
= pad
+ drbg_blocklen(drbg
);
456 unsigned char *temp
= iv
+ drbg_blocklen(drbg
);
458 unsigned int templen
= 0;
462 const unsigned char *K
= (unsigned char *)
463 "\x00\x01\x02\x03\x04\x05\x06\x07"
464 "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
465 "\x10\x11\x12\x13\x14\x15\x16\x17"
466 "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f";
468 size_t generated_len
= 0;
470 struct drbg_string
*seed
= NULL
;
472 memset(pad
, 0, drbg_blocklen(drbg
));
473 memset(iv
, 0, drbg_blocklen(drbg
));
474 memset(temp
, 0, drbg_statelen(drbg
));
476 /* 10.4.2 step 1 is implicit as we work byte-wise */
479 if ((512/8) < bytes_to_return
)
482 /* 10.4.2 step 2 -- calculate the entire length of all input data */
483 list_for_each_entry(seed
, seedlist
, list
)
484 inputlen
+= seed
->len
;
485 drbg_int2byte(&L_N
[0], inputlen
, 4);
488 drbg_int2byte(&L_N
[4], bytes_to_return
, 4);
490 /* 10.4.2 step 5: length is L_N, input_string, one byte, padding */
491 padlen
= (inputlen
+ sizeof(L_N
) + 1) % (drbg_blocklen(drbg
));
492 /* wrap the padlen appropriately */
494 padlen
= drbg_blocklen(drbg
) - padlen
;
496 * pad / padlen contains the 0x80 byte and the following zero bytes.
497 * As the calculated padlen value only covers the number of zero
498 * bytes, this value has to be incremented by one for the 0x80 byte.
503 /* 10.4.2 step 4 -- first fill the linked list and then order it */
504 drbg_string_fill(&S1
, iv
, drbg_blocklen(drbg
));
505 list_add_tail(&S1
.list
, &bcc_list
);
506 drbg_string_fill(&S2
, L_N
, sizeof(L_N
));
507 list_add_tail(&S2
.list
, &bcc_list
);
508 list_splice_tail(seedlist
, &bcc_list
);
509 drbg_string_fill(&S4
, pad
, padlen
);
510 list_add_tail(&S4
.list
, &bcc_list
);
513 while (templen
< (drbg_keylen(drbg
) + (drbg_blocklen(drbg
)))) {
515 * 10.4.2 step 9.1 - the padding is implicit as the buffer
516 * holds zeros after allocation -- even the increment of i
517 * is irrelevant as the increment remains within length of i
519 drbg_int2byte(iv
, i
, 4);
520 /* 10.4.2 step 9.2 -- BCC and concatenation with temp */
521 ret
= drbg_ctr_bcc(drbg
, temp
+ templen
, K
, &bcc_list
);
524 /* 10.4.2 step 9.3 */
526 templen
+= drbg_blocklen(drbg
);
530 X
= temp
+ (drbg_keylen(drbg
));
531 drbg_string_fill(&cipherin
, X
, drbg_blocklen(drbg
));
533 /* 10.4.2 step 12: overwriting of outval is implemented in next step */
536 while (generated_len
< bytes_to_return
) {
539 * 10.4.2 step 13.1: the truncation of the key length is
540 * implicit as the key is only drbg_blocklen in size based on
541 * the implementation of the cipher function callback
543 ret
= drbg_kcapi_sym(drbg
, temp
, X
, &cipherin
);
546 blocklen
= (drbg_blocklen(drbg
) <
547 (bytes_to_return
- generated_len
)) ?
548 drbg_blocklen(drbg
) :
549 (bytes_to_return
- generated_len
);
550 /* 10.4.2 step 13.2 and 14 */
551 memcpy(df_data
+ generated_len
, X
, blocklen
);
552 generated_len
+= blocklen
;
558 memset(iv
, 0, drbg_blocklen(drbg
));
559 memset(temp
, 0, drbg_statelen(drbg
));
560 memset(pad
, 0, drbg_blocklen(drbg
));
564 /* update function of CTR DRBG as defined in 10.2.1.2 */
565 static int drbg_ctr_update(struct drbg_state
*drbg
, struct list_head
*seed
,
569 /* 10.2.1.2 step 1 */
570 unsigned char *temp
= drbg
->scratchpad
;
571 unsigned char *df_data
= drbg
->scratchpad
+ drbg_statelen(drbg
) +
573 unsigned char *temp_p
, *df_data_p
; /* pointer to iterate over buffers */
574 unsigned int len
= 0;
575 struct drbg_string cipherin
;
576 unsigned char prefix
= DRBG_PREFIX1
;
578 memset(temp
, 0, drbg_statelen(drbg
) + drbg_blocklen(drbg
));
579 memset(df_data
, 0, drbg_statelen(drbg
));
581 /* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */
583 ret
= drbg_ctr_df(drbg
, df_data
, drbg_statelen(drbg
), seed
);
588 drbg_string_fill(&cipherin
, drbg
->V
, drbg_blocklen(drbg
));
590 * 10.2.1.3.2 steps 2 and 3 are already covered as the allocation
591 * zeroizes all memory during initialization
593 while (len
< (drbg_statelen(drbg
))) {
594 /* 10.2.1.2 step 2.1 */
595 drbg_add_buf(drbg
->V
, drbg_blocklen(drbg
), &prefix
, 1);
597 * 10.2.1.2 step 2.2 */
598 ret
= drbg_kcapi_sym(drbg
, drbg
->C
, temp
+ len
, &cipherin
);
601 /* 10.2.1.2 step 2.3 and 3 */
602 len
+= drbg_blocklen(drbg
);
605 /* 10.2.1.2 step 4 */
608 for (len
= 0; len
< drbg_statelen(drbg
); len
++) {
609 *temp_p
^= *df_data_p
;
610 df_data_p
++; temp_p
++;
613 /* 10.2.1.2 step 5 */
614 memcpy(drbg
->C
, temp
, drbg_keylen(drbg
));
615 /* 10.2.1.2 step 6 */
616 memcpy(drbg
->V
, temp
+ drbg_keylen(drbg
), drbg_blocklen(drbg
));
620 memset(temp
, 0, drbg_statelen(drbg
) + drbg_blocklen(drbg
));
621 memset(df_data
, 0, drbg_statelen(drbg
));
626 * scratchpad use: drbg_ctr_update is called independently from
627 * drbg_ctr_extract_bytes. Therefore, the scratchpad is reused
629 /* Generate function of CTR DRBG as defined in 10.2.1.5.2 */
630 static int drbg_ctr_generate(struct drbg_state
*drbg
,
631 unsigned char *buf
, unsigned int buflen
,
632 struct drbg_string
*addtl
)
636 struct drbg_string data
;
637 unsigned char prefix
= DRBG_PREFIX1
;
639 memset(drbg
->scratchpad
, 0, drbg_blocklen(drbg
));
641 /* 10.2.1.5.2 step 2 */
642 if (addtl
&& 0 < addtl
->len
) {
643 LIST_HEAD(addtllist
);
645 list_add_tail(&addtl
->list
, &addtllist
);
646 ret
= drbg_ctr_update(drbg
, &addtllist
, 1);
651 /* 10.2.1.5.2 step 4.1 */
652 drbg_add_buf(drbg
->V
, drbg_blocklen(drbg
), &prefix
, 1);
653 drbg_string_fill(&data
, drbg
->V
, drbg_blocklen(drbg
));
654 while (len
< buflen
) {
656 /* 10.2.1.5.2 step 4.2 */
657 ret
= drbg_kcapi_sym(drbg
, drbg
->C
, drbg
->scratchpad
, &data
);
662 outlen
= (drbg_blocklen(drbg
) < (buflen
- len
)) ?
663 drbg_blocklen(drbg
) : (buflen
- len
);
664 if (!drbg_fips_continuous_test(drbg
, drbg
->scratchpad
)) {
665 /* 10.2.1.5.2 step 6 */
666 drbg_add_buf(drbg
->V
, drbg_blocklen(drbg
), &prefix
, 1);
669 /* 10.2.1.5.2 step 4.3 */
670 memcpy(buf
+ len
, drbg
->scratchpad
, outlen
);
672 /* 10.2.1.5.2 step 6 */
674 drbg_add_buf(drbg
->V
, drbg_blocklen(drbg
), &prefix
, 1);
679 * The following call invokes the DF function again which could be
680 * optimized. In step 2, the "additional_input" after step 2 is the
681 * output of the DF function. If this result would be saved, the DF
682 * function would not need to be invoked again at this point.
684 if (addtl
&& 0 < addtl
->len
) {
685 LIST_HEAD(addtllist
);
687 list_add_tail(&addtl
->list
, &addtllist
);
688 ret
= drbg_ctr_update(drbg
, &addtllist
, 1);
690 ret
= drbg_ctr_update(drbg
, NULL
, 1);
696 memset(drbg
->scratchpad
, 0, drbg_blocklen(drbg
));
700 static struct drbg_state_ops drbg_ctr_ops
= {
701 .update
= drbg_ctr_update
,
702 .generate
= drbg_ctr_generate
,
703 .crypto_init
= drbg_init_sym_kernel
,
704 .crypto_fini
= drbg_fini_sym_kernel
,
706 #endif /* CONFIG_CRYPTO_DRBG_CTR */
708 /******************************************************************
709 * HMAC DRBG callback functions
710 ******************************************************************/
712 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
713 static int drbg_kcapi_hash(struct drbg_state
*drbg
, const unsigned char *key
,
714 unsigned char *outval
, const struct list_head
*in
);
715 static int drbg_init_hash_kernel(struct drbg_state
*drbg
);
716 static int drbg_fini_hash_kernel(struct drbg_state
*drbg
);
717 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
719 #ifdef CONFIG_CRYPTO_DRBG_HMAC
720 /* update function of HMAC DRBG as defined in 10.1.2.2 */
721 static int drbg_hmac_update(struct drbg_state
*drbg
, struct list_head
*seed
,
726 struct drbg_string seed1
, seed2
, vdata
;
728 LIST_HEAD(vdatalist
);
731 /* 10.1.2.3 step 2 */
732 memset(drbg
->C
, 0, drbg_statelen(drbg
));
733 memset(drbg
->V
, 1, drbg_statelen(drbg
));
736 drbg_string_fill(&seed1
, drbg
->V
, drbg_statelen(drbg
));
737 list_add_tail(&seed1
.list
, &seedlist
);
738 /* buffer of seed2 will be filled in for loop below with one byte */
739 drbg_string_fill(&seed2
, NULL
, 1);
740 list_add_tail(&seed2
.list
, &seedlist
);
741 /* input data of seed is allowed to be NULL at this point */
743 list_splice_tail(seed
, &seedlist
);
745 drbg_string_fill(&vdata
, drbg
->V
, drbg_statelen(drbg
));
746 list_add_tail(&vdata
.list
, &vdatalist
);
747 for (i
= 2; 0 < i
; i
--) {
748 /* first round uses 0x0, second 0x1 */
749 unsigned char prefix
= DRBG_PREFIX0
;
751 prefix
= DRBG_PREFIX1
;
752 /* 10.1.2.2 step 1 and 4 -- concatenation and HMAC for key */
754 ret
= drbg_kcapi_hash(drbg
, drbg
->C
, drbg
->C
, &seedlist
);
758 /* 10.1.2.2 step 2 and 5 -- HMAC for V */
759 ret
= drbg_kcapi_hash(drbg
, drbg
->C
, drbg
->V
, &vdatalist
);
763 /* 10.1.2.2 step 3 */
771 /* generate function of HMAC DRBG as defined in 10.1.2.5 */
772 static int drbg_hmac_generate(struct drbg_state
*drbg
,
775 struct drbg_string
*addtl
)
779 struct drbg_string data
;
782 /* 10.1.2.5 step 2 */
783 if (addtl
&& 0 < addtl
->len
) {
784 LIST_HEAD(addtllist
);
786 list_add_tail(&addtl
->list
, &addtllist
);
787 ret
= drbg_hmac_update(drbg
, &addtllist
, 1);
792 drbg_string_fill(&data
, drbg
->V
, drbg_statelen(drbg
));
793 list_add_tail(&data
.list
, &datalist
);
794 while (len
< buflen
) {
795 unsigned int outlen
= 0;
796 /* 10.1.2.5 step 4.1 */
797 ret
= drbg_kcapi_hash(drbg
, drbg
->C
, drbg
->V
, &datalist
);
800 outlen
= (drbg_blocklen(drbg
) < (buflen
- len
)) ?
801 drbg_blocklen(drbg
) : (buflen
- len
);
802 if (!drbg_fips_continuous_test(drbg
, drbg
->V
))
805 /* 10.1.2.5 step 4.2 */
806 memcpy(buf
+ len
, drbg
->V
, outlen
);
810 /* 10.1.2.5 step 6 */
811 if (addtl
&& 0 < addtl
->len
) {
812 LIST_HEAD(addtllist
);
814 list_add_tail(&addtl
->list
, &addtllist
);
815 ret
= drbg_hmac_update(drbg
, &addtllist
, 1);
817 ret
= drbg_hmac_update(drbg
, NULL
, 1);
825 static struct drbg_state_ops drbg_hmac_ops
= {
826 .update
= drbg_hmac_update
,
827 .generate
= drbg_hmac_generate
,
828 .crypto_init
= drbg_init_hash_kernel
,
829 .crypto_fini
= drbg_fini_hash_kernel
,
832 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
834 /******************************************************************
835 * Hash DRBG callback functions
836 ******************************************************************/
838 #ifdef CONFIG_CRYPTO_DRBG_HASH
840 * scratchpad usage: as drbg_hash_update and drbg_hash_df are used
841 * interlinked, the scratchpad is used as follows:
843 * start: drbg->scratchpad
844 * length: drbg_statelen(drbg)
846 * start: drbg->scratchpad + drbg_statelen(drbg)
847 * length: drbg_blocklen(drbg)
849 * drbg_hash_process_addtl uses the scratchpad, but fully completes
850 * before either of the functions mentioned before are invoked. Therefore,
851 * drbg_hash_process_addtl does not need to be specifically considered.
854 /* Derivation Function for Hash DRBG as defined in 10.4.1 */
855 static int drbg_hash_df(struct drbg_state
*drbg
,
856 unsigned char *outval
, size_t outlen
,
857 struct list_head
*entropylist
)
861 unsigned char input
[5];
862 unsigned char *tmp
= drbg
->scratchpad
+ drbg_statelen(drbg
);
863 struct drbg_string data
;
865 memset(tmp
, 0, drbg_blocklen(drbg
));
869 drbg_int2byte(&input
[1], (outlen
* 8), 4);
871 /* 10.4.1 step 4.1 -- concatenation of data for input into hash */
872 drbg_string_fill(&data
, input
, 5);
873 list_add(&data
.list
, entropylist
);
876 while (len
< outlen
) {
878 /* 10.4.1 step 4.1 */
879 ret
= drbg_kcapi_hash(drbg
, NULL
, tmp
, entropylist
);
882 /* 10.4.1 step 4.2 */
884 blocklen
= (drbg_blocklen(drbg
) < (outlen
- len
)) ?
885 drbg_blocklen(drbg
) : (outlen
- len
);
886 memcpy(outval
+ len
, tmp
, blocklen
);
891 memset(tmp
, 0, drbg_blocklen(drbg
));
895 /* update function for Hash DRBG as defined in 10.1.1.2 / 10.1.1.3 */
896 static int drbg_hash_update(struct drbg_state
*drbg
, struct list_head
*seed
,
900 struct drbg_string data1
, data2
;
902 LIST_HEAD(datalist2
);
903 unsigned char *V
= drbg
->scratchpad
;
904 unsigned char prefix
= DRBG_PREFIX1
;
906 memset(drbg
->scratchpad
, 0, drbg_statelen(drbg
));
911 /* 10.1.1.3 step 1 */
912 memcpy(V
, drbg
->V
, drbg_statelen(drbg
));
913 drbg_string_fill(&data1
, &prefix
, 1);
914 list_add_tail(&data1
.list
, &datalist
);
915 drbg_string_fill(&data2
, V
, drbg_statelen(drbg
));
916 list_add_tail(&data2
.list
, &datalist
);
918 list_splice_tail(seed
, &datalist
);
920 /* 10.1.1.2 / 10.1.1.3 step 2 and 3 */
921 ret
= drbg_hash_df(drbg
, drbg
->V
, drbg_statelen(drbg
), &datalist
);
925 /* 10.1.1.2 / 10.1.1.3 step 4 */
926 prefix
= DRBG_PREFIX0
;
927 drbg_string_fill(&data1
, &prefix
, 1);
928 list_add_tail(&data1
.list
, &datalist2
);
929 drbg_string_fill(&data2
, drbg
->V
, drbg_statelen(drbg
));
930 list_add_tail(&data2
.list
, &datalist2
);
931 /* 10.1.1.2 / 10.1.1.3 step 4 */
932 ret
= drbg_hash_df(drbg
, drbg
->C
, drbg_statelen(drbg
), &datalist2
);
935 memset(drbg
->scratchpad
, 0, drbg_statelen(drbg
));
939 /* processing of additional information string for Hash DRBG */
940 static int drbg_hash_process_addtl(struct drbg_state
*drbg
,
941 struct drbg_string
*addtl
)
944 struct drbg_string data1
, data2
;
946 unsigned char prefix
= DRBG_PREFIX2
;
948 /* this is value w as per documentation */
949 memset(drbg
->scratchpad
, 0, drbg_blocklen(drbg
));
951 /* 10.1.1.4 step 2 */
952 if (!addtl
|| 0 == addtl
->len
)
955 /* 10.1.1.4 step 2a */
956 drbg_string_fill(&data1
, &prefix
, 1);
957 drbg_string_fill(&data2
, drbg
->V
, drbg_statelen(drbg
));
958 list_add_tail(&data1
.list
, &datalist
);
959 list_add_tail(&data2
.list
, &datalist
);
960 list_add_tail(&addtl
->list
, &datalist
);
961 ret
= drbg_kcapi_hash(drbg
, NULL
, drbg
->scratchpad
, &datalist
);
965 /* 10.1.1.4 step 2b */
966 drbg_add_buf(drbg
->V
, drbg_statelen(drbg
),
967 drbg
->scratchpad
, drbg_blocklen(drbg
));
970 memset(drbg
->scratchpad
, 0, drbg_blocklen(drbg
));
974 /* Hashgen defined in 10.1.1.4 */
975 static int drbg_hash_hashgen(struct drbg_state
*drbg
,
981 unsigned char *src
= drbg
->scratchpad
;
982 unsigned char *dst
= drbg
->scratchpad
+ drbg_statelen(drbg
);
983 struct drbg_string data
;
985 unsigned char prefix
= DRBG_PREFIX1
;
987 memset(src
, 0, drbg_statelen(drbg
));
988 memset(dst
, 0, drbg_blocklen(drbg
));
990 /* 10.1.1.4 step hashgen 2 */
991 memcpy(src
, drbg
->V
, drbg_statelen(drbg
));
993 drbg_string_fill(&data
, src
, drbg_statelen(drbg
));
994 list_add_tail(&data
.list
, &datalist
);
995 while (len
< buflen
) {
996 unsigned int outlen
= 0;
997 /* 10.1.1.4 step hashgen 4.1 */
998 ret
= drbg_kcapi_hash(drbg
, NULL
, dst
, &datalist
);
1003 outlen
= (drbg_blocklen(drbg
) < (buflen
- len
)) ?
1004 drbg_blocklen(drbg
) : (buflen
- len
);
1005 if (!drbg_fips_continuous_test(drbg
, dst
)) {
1006 drbg_add_buf(src
, drbg_statelen(drbg
), &prefix
, 1);
1009 /* 10.1.1.4 step hashgen 4.2 */
1010 memcpy(buf
+ len
, dst
, outlen
);
1012 /* 10.1.1.4 hashgen step 4.3 */
1014 drbg_add_buf(src
, drbg_statelen(drbg
), &prefix
, 1);
1018 memset(drbg
->scratchpad
, 0,
1019 (drbg_statelen(drbg
) + drbg_blocklen(drbg
)));
1023 /* generate function for Hash DRBG as defined in 10.1.1.4 */
1024 static int drbg_hash_generate(struct drbg_state
*drbg
,
1025 unsigned char *buf
, unsigned int buflen
,
1026 struct drbg_string
*addtl
)
1030 unsigned char req
[8];
1031 unsigned char prefix
= DRBG_PREFIX3
;
1032 struct drbg_string data1
, data2
;
1033 LIST_HEAD(datalist
);
1035 /* 10.1.1.4 step 2 */
1036 ret
= drbg_hash_process_addtl(drbg
, addtl
);
1039 /* 10.1.1.4 step 3 */
1040 len
= drbg_hash_hashgen(drbg
, buf
, buflen
);
1042 /* this is the value H as documented in 10.1.1.4 */
1043 memset(drbg
->scratchpad
, 0, drbg_blocklen(drbg
));
1044 /* 10.1.1.4 step 4 */
1045 drbg_string_fill(&data1
, &prefix
, 1);
1046 list_add_tail(&data1
.list
, &datalist
);
1047 drbg_string_fill(&data2
, drbg
->V
, drbg_statelen(drbg
));
1048 list_add_tail(&data2
.list
, &datalist
);
1049 ret
= drbg_kcapi_hash(drbg
, NULL
, drbg
->scratchpad
, &datalist
);
1055 /* 10.1.1.4 step 5 */
1056 drbg_add_buf(drbg
->V
, drbg_statelen(drbg
),
1057 drbg
->scratchpad
, drbg_blocklen(drbg
));
1058 drbg_add_buf(drbg
->V
, drbg_statelen(drbg
),
1059 drbg
->C
, drbg_statelen(drbg
));
1060 drbg_int2byte(req
, drbg
->reseed_ctr
, sizeof(req
));
1061 drbg_add_buf(drbg
->V
, drbg_statelen(drbg
), req
, 8);
1064 memset(drbg
->scratchpad
, 0, drbg_blocklen(drbg
));
1069 * scratchpad usage: as update and generate are used isolated, both
1070 * can use the scratchpad
1072 static struct drbg_state_ops drbg_hash_ops
= {
1073 .update
= drbg_hash_update
,
1074 .generate
= drbg_hash_generate
,
1075 .crypto_init
= drbg_init_hash_kernel
,
1076 .crypto_fini
= drbg_fini_hash_kernel
,
1078 #endif /* CONFIG_CRYPTO_DRBG_HASH */
1080 /******************************************************************
1081 * Functions common for DRBG implementations
1082 ******************************************************************/
1085 * Seeding or reseeding of the DRBG
1087 * @drbg: DRBG state struct
1088 * @pers: personalization / additional information buffer
1089 * @reseed: 0 for initial seed process, 1 for reseeding
1093 * error value otherwise
1095 static int drbg_seed(struct drbg_state
*drbg
, struct drbg_string
*pers
,
1099 unsigned char *entropy
= NULL
;
1100 size_t entropylen
= 0;
1101 struct drbg_string data1
;
1102 LIST_HEAD(seedlist
);
1104 /* 9.1 / 9.2 / 9.3.1 step 3 */
1105 if (pers
&& pers
->len
> (drbg_max_addtl(drbg
))) {
1106 pr_devel("DRBG: personalization string too long %lu\n",
1111 if (drbg
->test_data
&& drbg
->test_data
->testentropy
) {
1112 drbg_string_fill(&data1
, drbg
->test_data
->testentropy
->buf
,
1113 drbg
->test_data
->testentropy
->len
);
1114 pr_devel("DRBG: using test entropy\n");
1117 * Gather entropy equal to the security strength of the DRBG.
1118 * With a derivation function, a nonce is required in addition
1119 * to the entropy. A nonce must be at least 1/2 of the security
1120 * strength of the DRBG in size. Thus, entropy * nonce is 3/2
1121 * of the strength. The consideration of a nonce is only
1122 * applicable during initial seeding.
1124 entropylen
= drbg_sec_strength(drbg
->core
->flags
);
1128 entropylen
= ((entropylen
+ 1) / 2) * 3;
1129 pr_devel("DRBG: (re)seeding with %zu bytes of entropy\n",
1131 entropy
= kzalloc(entropylen
, GFP_KERNEL
);
1134 get_random_bytes(entropy
, entropylen
);
1135 drbg_string_fill(&data1
, entropy
, entropylen
);
1137 list_add_tail(&data1
.list
, &seedlist
);
1140 * concatenation of entropy with personalization str / addtl input)
1141 * the variable pers is directly handed in by the caller, so check its
1142 * contents whether it is appropriate
1144 if (pers
&& pers
->buf
&& 0 < pers
->len
) {
1145 list_add_tail(&pers
->list
, &seedlist
);
1146 pr_devel("DRBG: using personalization string\n");
1149 ret
= drbg
->d_ops
->update(drbg
, &seedlist
, reseed
);
1153 drbg
->seeded
= true;
1154 /* 10.1.1.2 / 10.1.1.3 step 5 */
1155 drbg
->reseed_ctr
= 1;
1163 /* Free all substructures in a DRBG state without the DRBG state structure */
1164 static inline void drbg_dealloc_state(struct drbg_state
*drbg
)
1174 if (drbg
->scratchpad
)
1175 kzfree(drbg
->scratchpad
);
1176 drbg
->scratchpad
= NULL
;
1177 drbg
->reseed_ctr
= 0;
1178 #ifdef CONFIG_CRYPTO_FIPS
1182 drbg
->fips_primed
= false;
1187 * Allocate all sub-structures for a DRBG state.
1188 * The DRBG state structure must already be allocated.
1190 static inline int drbg_alloc_state(struct drbg_state
*drbg
)
1193 unsigned int sb_size
= 0;
1198 drbg
->V
= kzalloc(drbg_statelen(drbg
), GFP_KERNEL
);
1201 drbg
->C
= kzalloc(drbg_statelen(drbg
), GFP_KERNEL
);
1204 #ifdef CONFIG_CRYPTO_FIPS
1205 drbg
->prev
= kzalloc(drbg_blocklen(drbg
), GFP_KERNEL
);
1208 drbg
->fips_primed
= false;
1210 /* scratchpad is only generated for CTR and Hash */
1211 if (drbg
->core
->flags
& DRBG_HMAC
)
1213 else if (drbg
->core
->flags
& DRBG_CTR
)
1214 sb_size
= drbg_statelen(drbg
) + drbg_blocklen(drbg
) + /* temp */
1215 drbg_statelen(drbg
) + /* df_data */
1216 drbg_blocklen(drbg
) + /* pad */
1217 drbg_blocklen(drbg
) + /* iv */
1218 drbg_statelen(drbg
) + drbg_blocklen(drbg
); /* temp */
1220 sb_size
= drbg_statelen(drbg
) + drbg_blocklen(drbg
);
1223 drbg
->scratchpad
= kzalloc(sb_size
, GFP_KERNEL
);
1224 if (!drbg
->scratchpad
)
1227 spin_lock_init(&drbg
->drbg_lock
);
1231 drbg_dealloc_state(drbg
);
1236 * Strategy to avoid holding long term locks: generate a shadow copy of DRBG
1237 * and perform all operations on this shadow copy. After finishing, restore
1238 * the updated state of the shadow copy into original drbg state. This way,
1239 * only the read and write operations of the original drbg state must be
1242 static inline void drbg_copy_drbg(struct drbg_state
*src
,
1243 struct drbg_state
*dst
)
1247 memcpy(dst
->V
, src
->V
, drbg_statelen(src
));
1248 memcpy(dst
->C
, src
->C
, drbg_statelen(src
));
1249 dst
->reseed_ctr
= src
->reseed_ctr
;
1250 dst
->seeded
= src
->seeded
;
1252 #ifdef CONFIG_CRYPTO_FIPS
1253 dst
->fips_primed
= src
->fips_primed
;
1254 memcpy(dst
->prev
, src
->prev
, drbg_blocklen(src
));
1258 * scratchpad is initialized drbg_alloc_state;
1259 * priv_data is initialized with call to crypto_init;
1260 * d_ops and core are set outside, as these parameters are const;
1261 * test_data is set outside to prevent it being copied back.
1265 static int drbg_make_shadow(struct drbg_state
*drbg
, struct drbg_state
**shadow
)
1268 struct drbg_state
*tmp
= NULL
;
1270 if (!drbg
|| !drbg
->core
|| !drbg
->V
|| !drbg
->C
) {
1271 pr_devel("DRBG: attempt to generate shadow copy for "
1272 "uninitialized DRBG state rejected\n");
1275 /* HMAC does not have a scratchpad */
1276 if (!(drbg
->core
->flags
& DRBG_HMAC
) && NULL
== drbg
->scratchpad
)
1279 tmp
= kzalloc(sizeof(struct drbg_state
), GFP_KERNEL
);
1283 /* read-only data as they are defined as const, no lock needed */
1284 tmp
->core
= drbg
->core
;
1285 tmp
->d_ops
= drbg
->d_ops
;
1287 ret
= drbg_alloc_state(tmp
);
1291 spin_lock_bh(&drbg
->drbg_lock
);
1292 drbg_copy_drbg(drbg
, tmp
);
1293 /* only make a link to the test buffer, as we only read that data */
1294 tmp
->test_data
= drbg
->test_data
;
1295 spin_unlock_bh(&drbg
->drbg_lock
);
1305 static void drbg_restore_shadow(struct drbg_state
*drbg
,
1306 struct drbg_state
**shadow
)
1308 struct drbg_state
*tmp
= *shadow
;
1310 spin_lock_bh(&drbg
->drbg_lock
);
1311 drbg_copy_drbg(tmp
, drbg
);
1312 spin_unlock_bh(&drbg
->drbg_lock
);
1313 drbg_dealloc_state(tmp
);
1318 /*************************************************************************
1319 * DRBG interface functions
1320 *************************************************************************/
1323 * DRBG generate function as required by SP800-90A - this function
1324 * generates random numbers
1326 * @drbg DRBG state handle
1327 * @buf Buffer where to store the random numbers -- the buffer must already
1328 * be pre-allocated by caller
1329 * @buflen Length of output buffer - this value defines the number of random
1330 * bytes pulled from DRBG
1331 * @addtl Additional input that is mixed into state, may be NULL -- note
1332 * the entropy is pulled by the DRBG internally unconditionally
1333 * as defined in SP800-90A. The additional input is mixed into
1334 * the state in addition to the pulled entropy.
1336 * return: generated number of bytes
1338 static int drbg_generate(struct drbg_state
*drbg
,
1339 unsigned char *buf
, unsigned int buflen
,
1340 struct drbg_string
*addtl
)
1343 struct drbg_state
*shadow
= NULL
;
1345 if (0 == buflen
|| !buf
) {
1346 pr_devel("DRBG: no output buffer provided\n");
1349 if (addtl
&& NULL
== addtl
->buf
&& 0 < addtl
->len
) {
1350 pr_devel("DRBG: wrong format of additional information\n");
1354 len
= drbg_make_shadow(drbg
, &shadow
);
1356 pr_devel("DRBG: shadow copy cannot be generated\n");
1362 if (buflen
> (drbg_max_request_bytes(shadow
))) {
1363 pr_devel("DRBG: requested random numbers too large %u\n",
1368 /* 9.3.1 step 3 is implicit with the chosen DRBG */
1371 if (addtl
&& addtl
->len
> (drbg_max_addtl(shadow
))) {
1372 pr_devel("DRBG: additional information string too long %zu\n",
1376 /* 9.3.1 step 5 is implicit with the chosen DRBG */
1379 * 9.3.1 step 6 and 9 supplemented by 9.3.2 step c is implemented
1380 * here. The spec is a bit convoluted here, we make it simpler.
1382 if ((drbg_max_requests(shadow
)) < shadow
->reseed_ctr
)
1383 shadow
->seeded
= false;
1385 /* allocate cipher handle */
1386 if (shadow
->d_ops
->crypto_init
) {
1387 len
= shadow
->d_ops
->crypto_init(shadow
);
1392 if (shadow
->pr
|| !shadow
->seeded
) {
1393 pr_devel("DRBG: reseeding before generation (prediction "
1394 "resistance: %s, state %s)\n",
1395 drbg
->pr
? "true" : "false",
1396 drbg
->seeded
? "seeded" : "unseeded");
1397 /* 9.3.1 steps 7.1 through 7.3 */
1398 len
= drbg_seed(shadow
, addtl
, true);
1401 /* 9.3.1 step 7.4 */
1404 /* 9.3.1 step 8 and 10 */
1405 len
= shadow
->d_ops
->generate(shadow
, buf
, buflen
, addtl
);
1407 /* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */
1408 shadow
->reseed_ctr
++;
1413 * Section 11.3.3 requires to re-perform self tests after some
1414 * generated random numbers. The chosen value after which self
1415 * test is performed is arbitrary, but it should be reasonable.
1416 * However, we do not perform the self tests because of the following
1417 * reasons: it is mathematically impossible that the initial self tests
1418 * were successfully and the following are not. If the initial would
1419 * pass and the following would not, the kernel integrity is violated.
1420 * In this case, the entire kernel operation is questionable and it
1421 * is unlikely that the integrity violation only affects the
1422 * correct operation of the DRBG.
1424 * Albeit the following code is commented out, it is provided in
1425 * case somebody has a need to implement the test of 11.3.3.
1428 if (shadow
->reseed_ctr
&& !(shadow
->reseed_ctr
% 4096)) {
1430 pr_devel("DRBG: start to perform self test\n");
1431 if (drbg
->core
->flags
& DRBG_HMAC
)
1432 err
= alg_test("drbg_pr_hmac_sha256",
1433 "drbg_pr_hmac_sha256", 0, 0);
1434 else if (drbg
->core
->flags
& DRBG_CTR
)
1435 err
= alg_test("drbg_pr_ctr_aes128",
1436 "drbg_pr_ctr_aes128", 0, 0);
1438 err
= alg_test("drbg_pr_sha256",
1439 "drbg_pr_sha256", 0, 0);
1441 pr_err("DRBG: periodical self test failed\n");
1443 * uninstantiate implies that from now on, only errors
1444 * are returned when reusing this DRBG cipher handle
1446 drbg_uninstantiate(drbg
);
1447 drbg_dealloc_state(shadow
);
1451 pr_devel("DRBG: self test successful\n");
1457 if (shadow
->d_ops
->crypto_fini
)
1458 shadow
->d_ops
->crypto_fini(shadow
);
1459 drbg_restore_shadow(drbg
, &shadow
);
1464 * Wrapper around drbg_generate which can pull arbitrary long strings
1465 * from the DRBG without hitting the maximum request limitation.
1467 * Parameters: see drbg_generate
1468 * Return codes: see drbg_generate -- if one drbg_generate request fails,
1469 * the entire drbg_generate_long request fails
1471 static int drbg_generate_long(struct drbg_state
*drbg
,
1472 unsigned char *buf
, unsigned int buflen
,
1473 struct drbg_string
*addtl
)
1476 unsigned int slice
= 0;
1479 unsigned int chunk
= 0;
1480 slice
= ((buflen
- len
) / drbg_max_request_bytes(drbg
));
1481 chunk
= slice
? drbg_max_request_bytes(drbg
) : (buflen
- len
);
1482 tmplen
= drbg_generate(drbg
, buf
+ len
, chunk
, addtl
);
1486 } while (slice
> 0);
1491 * DRBG instantiation function as required by SP800-90A - this function
1492 * sets up the DRBG handle, performs the initial seeding and all sanity
1493 * checks required by SP800-90A
1495 * @drbg memory of state -- if NULL, new memory is allocated
1496 * @pers Personalization string that is mixed into state, may be NULL -- note
1497 * the entropy is pulled by the DRBG internally unconditionally
1498 * as defined in SP800-90A. The additional input is mixed into
1499 * the state in addition to the pulled entropy.
1500 * @coreref reference to core
1501 * @pr prediction resistance enabled
1505 * error value otherwise
1507 static int drbg_instantiate(struct drbg_state
*drbg
, struct drbg_string
*pers
,
1508 int coreref
, bool pr
)
1512 pr_devel("DRBG: Initializing DRBG core %d with prediction resistance "
1513 "%s\n", coreref
, pr
? "enabled" : "disabled");
1514 drbg
->core
= &drbg_cores
[coreref
];
1516 drbg
->seeded
= false;
1517 switch (drbg
->core
->flags
& DRBG_TYPE_MASK
) {
1518 #ifdef CONFIG_CRYPTO_DRBG_HMAC
1520 drbg
->d_ops
= &drbg_hmac_ops
;
1522 #endif /* CONFIG_CRYPTO_DRBG_HMAC */
1523 #ifdef CONFIG_CRYPTO_DRBG_HASH
1525 drbg
->d_ops
= &drbg_hash_ops
;
1527 #endif /* CONFIG_CRYPTO_DRBG_HASH */
1528 #ifdef CONFIG_CRYPTO_DRBG_CTR
1530 drbg
->d_ops
= &drbg_ctr_ops
;
1532 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1537 /* 9.1 step 1 is implicit with the selected DRBG type */
1540 * 9.1 step 2 is implicit as caller can select prediction resistance
1541 * and the flag is copied into drbg->flags --
1542 * all DRBG types support prediction resistance
1545 /* 9.1 step 4 is implicit in drbg_sec_strength */
1547 ret
= drbg_alloc_state(drbg
);
1552 if (drbg
->d_ops
->crypto_init
&& drbg
->d_ops
->crypto_init(drbg
))
1554 ret
= drbg_seed(drbg
, pers
, false);
1555 if (drbg
->d_ops
->crypto_fini
)
1556 drbg
->d_ops
->crypto_fini(drbg
);
1563 drbg_dealloc_state(drbg
);
1568 * DRBG uninstantiate function as required by SP800-90A - this function
1569 * frees all buffers and the DRBG handle
1571 * @drbg DRBG state handle
1576 static int drbg_uninstantiate(struct drbg_state
*drbg
)
1578 spin_lock_bh(&drbg
->drbg_lock
);
1579 drbg_dealloc_state(drbg
);
1580 /* no scrubbing of test_data -- this shall survive an uninstantiate */
1581 spin_unlock_bh(&drbg
->drbg_lock
);
1586 * Helper function for setting the test data in the DRBG
1588 * @drbg DRBG state handle
1589 * @test_data test data to sets
1591 static inline void drbg_set_testdata(struct drbg_state
*drbg
,
1592 struct drbg_test_data
*test_data
)
1594 if (!test_data
|| !test_data
->testentropy
)
1596 spin_lock_bh(&drbg
->drbg_lock
);
1597 drbg
->test_data
= test_data
;
1598 spin_unlock_bh(&drbg
->drbg_lock
);
1601 /***************************************************************
1602 * Kernel crypto API cipher invocations requested by DRBG
1603 ***************************************************************/
1605 #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
1607 struct shash_desc shash
;
1611 static int drbg_init_hash_kernel(struct drbg_state
*drbg
)
1613 struct sdesc
*sdesc
;
1614 struct crypto_shash
*tfm
;
1616 tfm
= crypto_alloc_shash(drbg
->core
->backend_cra_name
, 0, 0);
1618 pr_info("DRBG: could not allocate digest TFM handle\n");
1619 return PTR_ERR(tfm
);
1621 BUG_ON(drbg_blocklen(drbg
) != crypto_shash_digestsize(tfm
));
1622 sdesc
= kzalloc(sizeof(struct shash_desc
) + crypto_shash_descsize(tfm
),
1625 crypto_free_shash(tfm
);
1629 sdesc
->shash
.tfm
= tfm
;
1630 sdesc
->shash
.flags
= 0;
1631 drbg
->priv_data
= sdesc
;
1635 static int drbg_fini_hash_kernel(struct drbg_state
*drbg
)
1637 struct sdesc
*sdesc
= (struct sdesc
*)drbg
->priv_data
;
1639 crypto_free_shash(sdesc
->shash
.tfm
);
1642 drbg
->priv_data
= NULL
;
1646 static int drbg_kcapi_hash(struct drbg_state
*drbg
, const unsigned char *key
,
1647 unsigned char *outval
, const struct list_head
*in
)
1649 struct sdesc
*sdesc
= (struct sdesc
*)drbg
->priv_data
;
1650 struct drbg_string
*input
= NULL
;
1653 crypto_shash_setkey(sdesc
->shash
.tfm
, key
, drbg_statelen(drbg
));
1654 crypto_shash_init(&sdesc
->shash
);
1655 list_for_each_entry(input
, in
, list
)
1656 crypto_shash_update(&sdesc
->shash
, input
->buf
, input
->len
);
1657 return crypto_shash_final(&sdesc
->shash
, outval
);
1659 #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
1661 #ifdef CONFIG_CRYPTO_DRBG_CTR
1662 static int drbg_init_sym_kernel(struct drbg_state
*drbg
)
1665 struct crypto_blkcipher
*tfm
;
1667 tfm
= crypto_alloc_blkcipher(drbg
->core
->backend_cra_name
, 0, 0);
1669 pr_info("DRBG: could not allocate cipher TFM handle\n");
1670 return PTR_ERR(tfm
);
1672 BUG_ON(drbg_blocklen(drbg
) != crypto_blkcipher_blocksize(tfm
));
1673 drbg
->priv_data
= tfm
;
1677 static int drbg_fini_sym_kernel(struct drbg_state
*drbg
)
1679 struct crypto_blkcipher
*tfm
=
1680 (struct crypto_blkcipher
*)drbg
->priv_data
;
1682 crypto_free_blkcipher(tfm
);
1683 drbg
->priv_data
= NULL
;
1687 static int drbg_kcapi_sym(struct drbg_state
*drbg
, const unsigned char *key
,
1688 unsigned char *outval
, const struct drbg_string
*in
)
1691 struct scatterlist sg_in
, sg_out
;
1692 struct blkcipher_desc desc
;
1693 struct crypto_blkcipher
*tfm
=
1694 (struct crypto_blkcipher
*)drbg
->priv_data
;
1698 crypto_blkcipher_setkey(tfm
, key
, (drbg_keylen(drbg
)));
1699 /* there is only component in *in */
1700 sg_init_one(&sg_in
, in
->buf
, in
->len
);
1701 sg_init_one(&sg_out
, outval
, drbg_blocklen(drbg
));
1702 ret
= crypto_blkcipher_encrypt(&desc
, &sg_out
, &sg_in
, in
->len
);
1706 #endif /* CONFIG_CRYPTO_DRBG_CTR */
1708 /***************************************************************
1709 * Kernel crypto API interface to register DRBG
1710 ***************************************************************/
1713 * Look up the DRBG flags by given kernel crypto API cra_name
1714 * The code uses the drbg_cores definition to do this
1716 * @cra_name kernel crypto API cra_name
1717 * @coreref reference to integer which is filled with the pointer to
1718 * the applicable core
1719 * @pr reference for setting prediction resistance
1723 static inline void drbg_convert_tfm_core(const char *cra_driver_name
,
1724 int *coreref
, bool *pr
)
1731 /* disassemble the names */
1732 if (!memcmp(cra_driver_name
, "drbg_nopr_", 10)) {
1735 } else if (!memcmp(cra_driver_name
, "drbg_pr_", 8)) {
1741 /* remove the first part */
1742 len
= strlen(cra_driver_name
) - start
;
1743 for (i
= 0; ARRAY_SIZE(drbg_cores
) > i
; i
++) {
1744 if (!memcmp(cra_driver_name
+ start
, drbg_cores
[i
].cra_name
,
1752 static int drbg_kcapi_init(struct crypto_tfm
*tfm
)
1754 struct drbg_state
*drbg
= crypto_tfm_ctx(tfm
);
1758 drbg_convert_tfm_core(crypto_tfm_alg_name(tfm
), &coreref
, &pr
);
1760 * when personalization string is needed, the caller must call reset
1761 * and provide the personalization string as seed information
1763 return drbg_instantiate(drbg
, NULL
, coreref
, pr
);
1766 static void drbg_kcapi_cleanup(struct crypto_tfm
*tfm
)
1768 drbg_uninstantiate(crypto_tfm_ctx(tfm
));
1772 * Generate random numbers invoked by the kernel crypto API:
1773 * The API of the kernel crypto API is extended as follows:
1775 * If dlen is larger than zero, rdata is interpreted as the output buffer
1776 * where random data is to be stored.
1778 * If dlen is zero, rdata is interpreted as a pointer to a struct drbg_gen
1779 * which holds the additional information string that is used for the
1780 * DRBG generation process. The output buffer that is to be used to store
1781 * data is also pointed to by struct drbg_gen.
1783 static int drbg_kcapi_random(struct crypto_rng
*tfm
, u8
*rdata
,
1786 struct drbg_state
*drbg
= crypto_rng_ctx(tfm
);
1788 return drbg_generate_long(drbg
, rdata
, dlen
, NULL
);
1790 struct drbg_gen
*data
= (struct drbg_gen
*)rdata
;
1791 struct drbg_string addtl
;
1792 /* catch NULL pointer */
1795 drbg_set_testdata(drbg
, data
->test_data
);
1796 /* linked list variable is now local to allow modification */
1797 drbg_string_fill(&addtl
, data
->addtl
->buf
, data
->addtl
->len
);
1798 return drbg_generate_long(drbg
, data
->outbuf
, data
->outlen
,
1804 * Reset the DRBG invoked by the kernel crypto API
1805 * The reset implies a full re-initialization of the DRBG. Similar to the
1806 * generate function of drbg_kcapi_random, this function extends the
1807 * kernel crypto API interface with struct drbg_gen
1809 static int drbg_kcapi_reset(struct crypto_rng
*tfm
, u8
*seed
, unsigned int slen
)
1811 struct drbg_state
*drbg
= crypto_rng_ctx(tfm
);
1812 struct crypto_tfm
*tfm_base
= crypto_rng_tfm(tfm
);
1814 struct drbg_string seed_string
;
1817 drbg_uninstantiate(drbg
);
1818 drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base
), &coreref
,
1821 drbg_string_fill(&seed_string
, seed
, slen
);
1822 return drbg_instantiate(drbg
, &seed_string
, coreref
, pr
);
1824 struct drbg_gen
*data
= (struct drbg_gen
*)seed
;
1825 /* allow invocation of API call with NULL, 0 */
1827 return drbg_instantiate(drbg
, NULL
, coreref
, pr
);
1828 drbg_set_testdata(drbg
, data
->test_data
);
1829 /* linked list variable is now local to allow modification */
1830 drbg_string_fill(&seed_string
, data
->addtl
->buf
,
1832 return drbg_instantiate(drbg
, &seed_string
, coreref
, pr
);
1836 /***************************************************************
1837 * Kernel module: code to load the module
1838 ***************************************************************/
1841 * Tests as defined in 11.3.2 in addition to the cipher tests: testing
1842 * of the error handling.
1844 * Note: testing of failing seed source as defined in 11.3.2 is not applicable
1845 * as seed source of get_random_bytes does not fail.
1847 * Note 2: There is no sensible way of testing the reseed counter
1848 * enforcement, so skip it.
1850 static inline int __init
drbg_healthcheck_sanity(void)
1852 #ifdef CONFIG_CRYPTO_FIPS
1854 #define OUTBUFLEN 16
1855 unsigned char buf
[OUTBUFLEN
];
1856 struct drbg_state
*drbg
= NULL
;
1861 struct drbg_string addtl
;
1862 size_t max_addtllen
, max_request_bytes
;
1864 /* only perform test in FIPS mode */
1868 #ifdef CONFIG_CRYPTO_DRBG_CTR
1869 drbg_convert_tfm_core("drbg_nopr_ctr_aes128", &coreref
, &pr
);
1870 #elif CONFIG_CRYPTO_DRBG_HASH
1871 drbg_convert_tfm_core("drbg_nopr_sha256", &coreref
, &pr
);
1873 drbg_convert_tfm_core("drbg_nopr_hmac_sha256", &coreref
, &pr
);
1876 drbg
= kzalloc(sizeof(struct drbg_state
), GFP_KERNEL
);
1881 * if the following tests fail, it is likely that there is a buffer
1882 * overflow as buf is much smaller than the requested or provided
1883 * string lengths -- in case the error handling does not succeed
1884 * we may get an OOPS. And we want to get an OOPS as this is a
1888 /* get a valid instance of DRBG for following tests */
1889 ret
= drbg_instantiate(drbg
, NULL
, coreref
, pr
);
1894 max_addtllen
= drbg_max_addtl(drbg
);
1895 max_request_bytes
= drbg_max_request_bytes(drbg
);
1896 drbg_string_fill(&addtl
, buf
, max_addtllen
+ 1);
1897 /* overflow addtllen with additonal info string */
1898 len
= drbg_generate(drbg
, buf
, OUTBUFLEN
, &addtl
);
1900 /* overflow max_bits */
1901 len
= drbg_generate(drbg
, buf
, (max_request_bytes
+ 1), NULL
);
1903 drbg_uninstantiate(drbg
);
1905 /* overflow max addtllen with personalization string */
1906 ret
= drbg_instantiate(drbg
, &addtl
, coreref
, pr
);
1908 /* test uninstantated DRBG */
1909 len
= drbg_generate(drbg
, buf
, (max_request_bytes
+ 1), NULL
);
1911 /* all tests passed */
1914 pr_devel("DRBG: Sanity tests for failure code paths successfully "
1917 drbg_uninstantiate(drbg
);
1921 #else /* CONFIG_CRYPTO_FIPS */
1923 #endif /* CONFIG_CRYPTO_FIPS */
1926 static struct crypto_alg drbg_algs
[22];
1929 * Fill the array drbg_algs used to register the different DRBGs
1930 * with the kernel crypto API. To fill the array, the information
1931 * from drbg_cores[] is used.
1933 static inline void __init
drbg_fill_array(struct crypto_alg
*alg
,
1934 const struct drbg_core
*core
, int pr
)
1937 static int priority
= 100;
1939 memset(alg
, 0, sizeof(struct crypto_alg
));
1940 memcpy(alg
->cra_name
, "stdrng", 6);
1942 memcpy(alg
->cra_driver_name
, "drbg_pr_", 8);
1945 memcpy(alg
->cra_driver_name
, "drbg_nopr_", 10);
1948 memcpy(alg
->cra_driver_name
+ pos
, core
->cra_name
,
1949 strlen(core
->cra_name
));
1951 alg
->cra_priority
= priority
;
1954 * If FIPS mode enabled, the selected DRBG shall have the
1955 * highest cra_priority over other stdrng instances to ensure
1959 alg
->cra_priority
+= 200;
1961 alg
->cra_flags
= CRYPTO_ALG_TYPE_RNG
;
1962 alg
->cra_ctxsize
= sizeof(struct drbg_state
);
1963 alg
->cra_type
= &crypto_rng_type
;
1964 alg
->cra_module
= THIS_MODULE
;
1965 alg
->cra_init
= drbg_kcapi_init
;
1966 alg
->cra_exit
= drbg_kcapi_cleanup
;
1967 alg
->cra_u
.rng
.rng_make_random
= drbg_kcapi_random
;
1968 alg
->cra_u
.rng
.rng_reset
= drbg_kcapi_reset
;
1969 alg
->cra_u
.rng
.seedsize
= 0;
1972 static int __init
drbg_init(void)
1974 unsigned int i
= 0; /* pointer to drbg_algs */
1975 unsigned int j
= 0; /* pointer to drbg_cores */
1978 ret
= drbg_healthcheck_sanity();
1982 if (ARRAY_SIZE(drbg_cores
) * 2 > ARRAY_SIZE(drbg_algs
)) {
1983 pr_info("DRBG: Cannot register all DRBG types"
1984 "(slots needed: %lu, slots available: %lu)\n",
1985 ARRAY_SIZE(drbg_cores
) * 2, ARRAY_SIZE(drbg_algs
));
1990 * each DRBG definition can be used with PR and without PR, thus
1991 * we instantiate each DRBG in drbg_cores[] twice.
1993 * As the order of placing them into the drbg_algs array matters
1994 * (the later DRBGs receive a higher cra_priority) we register the
1995 * prediction resistance DRBGs first as the should not be too
1998 for (j
= 0; ARRAY_SIZE(drbg_cores
) > j
; j
++, i
++)
1999 drbg_fill_array(&drbg_algs
[i
], &drbg_cores
[j
], 1);
2000 for (j
= 0; ARRAY_SIZE(drbg_cores
) > j
; j
++, i
++)
2001 drbg_fill_array(&drbg_algs
[i
], &drbg_cores
[j
], 0);
2002 return crypto_register_algs(drbg_algs
, (ARRAY_SIZE(drbg_cores
) * 2));
2005 void __exit
drbg_exit(void)
2007 crypto_unregister_algs(drbg_algs
, (ARRAY_SIZE(drbg_cores
) * 2));
2010 module_init(drbg_init
);
2011 module_exit(drbg_exit
);
2012 MODULE_LICENSE("GPL");
2013 MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
2014 MODULE_DESCRIPTION("NIST SP800-90A Deterministic Random Bit Generator (DRBG) using following cores:"
2015 #ifdef CONFIG_CRYPTO_DRBG_HMAC
2018 #ifdef CONFIG_CRYPTO_DRBG_HASH
2021 #ifdef CONFIG_CRYPTO_DRBG_CTR