1*e7be843bSPierre Pronchery /*
2*e7be843bSPierre Pronchery * Copyright 2021 The OpenSSL Project Authors. All Rights Reserved.
3*e7be843bSPierre Pronchery *
4*e7be843bSPierre Pronchery * Licensed under the Apache License 2.0 (the "License"). You may not use
5*e7be843bSPierre Pronchery * this file except in compliance with the License. You can obtain a copy
6*e7be843bSPierre Pronchery * in the file LICENSE in the source distribution or at
7*e7be843bSPierre Pronchery * https://www.openssl.org/source/license.html
8*e7be843bSPierre Pronchery */
9*e7be843bSPierre Pronchery
10*e7be843bSPierre Pronchery #include "internal/cryptlib.h"
11*e7be843bSPierre Pronchery #include <openssl/opensslconf.h>
12*e7be843bSPierre Pronchery #include "crypto/rand_pool.h"
13*e7be843bSPierre Pronchery #include "prov/seeding.h"
14*e7be843bSPierre Pronchery
15*e7be843bSPierre Pronchery
16*e7be843bSPierre Pronchery #ifdef OPENSSL_RAND_SEED_RDCPU
17*e7be843bSPierre Pronchery #include "crypto/arm_arch.h"
18*e7be843bSPierre Pronchery
19*e7be843bSPierre Pronchery size_t OPENSSL_rndrrs_bytes(unsigned char *buf, size_t len);
20*e7be843bSPierre Pronchery
21*e7be843bSPierre Pronchery static size_t get_hardware_random_value(unsigned char *buf, size_t len);
22*e7be843bSPierre Pronchery
23*e7be843bSPierre Pronchery /*
24*e7be843bSPierre Pronchery * Acquire entropy using Arm-specific cpu instructions
25*e7be843bSPierre Pronchery *
26*e7be843bSPierre Pronchery * Uses the RNDRRS instruction. RNDR is never needed since
27*e7be843bSPierre Pronchery * RNDRRS will always be available if RNDR is an available
28*e7be843bSPierre Pronchery * instruction.
29*e7be843bSPierre Pronchery *
30*e7be843bSPierre Pronchery * Returns the total entropy count, if it exceeds the requested
31*e7be843bSPierre Pronchery * entropy count. Otherwise, returns an entropy count of 0.
32*e7be843bSPierre Pronchery */
ossl_prov_acquire_entropy_from_cpu(RAND_POOL * pool)33*e7be843bSPierre Pronchery size_t ossl_prov_acquire_entropy_from_cpu(RAND_POOL *pool)
34*e7be843bSPierre Pronchery {
35*e7be843bSPierre Pronchery size_t bytes_needed;
36*e7be843bSPierre Pronchery unsigned char *buffer;
37*e7be843bSPierre Pronchery
38*e7be843bSPierre Pronchery bytes_needed = ossl_rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
39*e7be843bSPierre Pronchery if (bytes_needed > 0) {
40*e7be843bSPierre Pronchery buffer = ossl_rand_pool_add_begin(pool, bytes_needed);
41*e7be843bSPierre Pronchery
42*e7be843bSPierre Pronchery if (buffer != NULL) {
43*e7be843bSPierre Pronchery if (get_hardware_random_value(buffer, bytes_needed) == bytes_needed)
44*e7be843bSPierre Pronchery ossl_rand_pool_add_end(pool, bytes_needed, 8 * bytes_needed);
45*e7be843bSPierre Pronchery else
46*e7be843bSPierre Pronchery ossl_rand_pool_add_end(pool, 0, 0);
47*e7be843bSPierre Pronchery }
48*e7be843bSPierre Pronchery }
49*e7be843bSPierre Pronchery
50*e7be843bSPierre Pronchery return ossl_rand_pool_entropy_available(pool);
51*e7be843bSPierre Pronchery }
52*e7be843bSPierre Pronchery
get_hardware_random_value(unsigned char * buf,size_t len)53*e7be843bSPierre Pronchery static size_t get_hardware_random_value(unsigned char *buf, size_t len)
54*e7be843bSPierre Pronchery {
55*e7be843bSPierre Pronchery /* Always use RNDRRS or nothing */
56*e7be843bSPierre Pronchery if (OPENSSL_armcap_P & ARMV8_RNG) {
57*e7be843bSPierre Pronchery if (OPENSSL_rndrrs_bytes(buf, len) != len)
58*e7be843bSPierre Pronchery return 0;
59*e7be843bSPierre Pronchery } else {
60*e7be843bSPierre Pronchery return 0;
61*e7be843bSPierre Pronchery }
62*e7be843bSPierre Pronchery return len;
63*e7be843bSPierre Pronchery }
64*e7be843bSPierre Pronchery
65*e7be843bSPierre Pronchery #else
66*e7be843bSPierre Pronchery NON_EMPTY_TRANSLATION_UNIT
67*e7be843bSPierre Pronchery #endif /* OPENSSL_RAND_SEED_RDCPU */
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