providers/implementations/rands/crngt.c

   1 /*
   2  * Copyright 2019-2020 The OpenSSL Project Authors. All Rights Reserved.
   3  * Copyright (c) 2019, Oracle and/or its affiliates.  All rights reserved.
   4  *
   5  * Licensed under the Apache License 2.0 (the "License").  You may not use
   6  * this file except in compliance with the License.  You can obtain a copy
   7  * in the file LICENSE in the source distribution or at
   8  * https://www.openssl.org/source/license.html
   9  */
  10
  11 /*
  12  * Implementation of the FIPS 140-2 section 4.9.2 Conditional Tests.
  13  */
  14
  15 #include <string.h>
  16 #include <openssl/evp.h>
  17 #include <openssl/core_dispatch.h>
  18 #include <openssl/params.h>
  19 #include <openssl/self_test.h>
  20 #include "prov/providercommon.h"
  21 #include "prov/provider_ctx.h"
  22 #include "internal/cryptlib.h"
  23 #include "prov/rand_pool.h"
  24 #include "drbg_local.h"
  25 #include "prov/seeding.h"
  26
  27 typedef struct crng_test_global_st {
  28     unsigned char crngt_prev[EVP_MAX_MD_SIZE];
  29     RAND_POOL *crngt_pool;
  30 } CRNG_TEST_GLOBAL;
  31
  32 static int crngt_get_entropy(OSSL_LIB_CTX *ctx, RAND_POOL *pool,
  33                              unsigned char *buf, unsigned char *md,
  34                              unsigned int *md_size)
  35 {
  36     int r;
  37     size_t n;
  38     unsigned char *p;
  39     EVP_MD *fmd;
  40
  41     if (pool == NULL)
  42         return 0;
  43
  44     n = prov_pool_acquire_entropy(pool);
  45     if (n >= CRNGT_BUFSIZ) {
  46         fmd = EVP_MD_fetch(ctx, "SHA256", "");
  47         if (fmd == NULL)
  48             return 0;
  49         p = rand_pool_detach(pool);
  50         r = EVP_Digest(p, CRNGT_BUFSIZ, md, md_size, fmd, NULL);
  51         if (r != 0)
  52             memcpy(buf, p, CRNGT_BUFSIZ);
  53         rand_pool_reattach(pool, p);
  54         EVP_MD_free(fmd);
  55         return r;
  56     }
  57     return 0;
  58 }
  59
  60 static void rand_crng_ossl_ctx_free(void *vcrngt_glob)
  61 {
  62     CRNG_TEST_GLOBAL *crngt_glob = vcrngt_glob;
  63
  64     rand_pool_free(crngt_glob->crngt_pool);
  65     OPENSSL_free(crngt_glob);
  66 }
  67
  68 static void *rand_crng_ossl_ctx_new(OSSL_LIB_CTX *ctx)
  69 {
  70     unsigned char buf[CRNGT_BUFSIZ];
  71     CRNG_TEST_GLOBAL *crngt_glob = OPENSSL_zalloc(sizeof(*crngt_glob));
  72
  73     if (crngt_glob == NULL)
  74         return NULL;
  75
  76     if ((crngt_glob->crngt_pool
  77          = rand_pool_new(0, 1, CRNGT_BUFSIZ, CRNGT_BUFSIZ)) == NULL) {
  78         OPENSSL_free(crngt_glob);
  79         return NULL;
  80     }
  81     if (crngt_get_entropy(ctx, crngt_glob->crngt_pool, buf,
  82                           crngt_glob->crngt_prev, NULL)) {
  83         OPENSSL_cleanse(buf, sizeof(buf));
  84         return crngt_glob;
  85     }
  86     rand_pool_free(crngt_glob->crngt_pool);
  87     OPENSSL_free(crngt_glob);
  88     return NULL;
  89 }
  90
  91 static const OSSL_LIB_CTX_METHOD rand_crng_ossl_ctx_method = {
  92     rand_crng_ossl_ctx_new,
  93     rand_crng_ossl_ctx_free,
  94 };
  95
  96 static int prov_crngt_compare_previous(const unsigned char *prev,
  97                                        const unsigned char *cur,
  98                                        size_t sz)
  99 {
 100     const int res = memcmp(prev, cur, sz) != 0;
 101
 102     if (!res)
 103         ossl_set_error_state(OSSL_SELF_TEST_TYPE_CRNG);
 104     return res;
 105 }
 106
 107 size_t prov_crngt_get_entropy(PROV_DRBG *drbg,
 108                               unsigned char **pout,
 109                               int entropy, size_t min_len, size_t max_len,
 110                               int prediction_resistance)
 111 {
 112     unsigned char buf[CRNGT_BUFSIZ], md[EVP_MAX_MD_SIZE];
 113     unsigned int sz;
 114     RAND_POOL *pool;
 115     size_t q, r = 0, s, t = 0;
 116     int attempts = 3, crng_test_pass = 1;
 117     OSSL_LIB_CTX *libctx = PROV_LIBRARY_CONTEXT_OF(drbg->provctx);
 118     CRNG_TEST_GLOBAL *crngt_glob
 119         = ossl_lib_ctx_get_data(libctx, OSSL_LIB_CTX_RAND_CRNGT_INDEX,
 120                                 &rand_crng_ossl_ctx_method);
 121     OSSL_CALLBACK *stcb = NULL;
 122     void *stcbarg = NULL;
 123     OSSL_SELF_TEST *st = NULL;
 124
 125     if (crngt_glob == NULL)
 126         return 0;
 127
 128     if ((pool = rand_pool_new(entropy, 1, min_len, max_len)) == NULL)
 129         return 0;
 130
 131     OSSL_SELF_TEST_get_callback(libctx, &stcb, &stcbarg);
 132     if (stcb != NULL) {
 133         st = OSSL_SELF_TEST_new(stcb, stcbarg);
 134         if (st == NULL)
 135             goto err;
 136         OSSL_SELF_TEST_onbegin(st, OSSL_SELF_TEST_TYPE_CRNG,
 137                                OSSL_SELF_TEST_DESC_RNG);
 138     }
 139
 140     while ((q = rand_pool_bytes_needed(pool, 1)) > 0 && attempts-- > 0) {
 141         s = q > sizeof(buf) ? sizeof(buf) : q;
 142         if (!crngt_get_entropy(libctx, crngt_glob->crngt_pool, buf, md, &sz))
 143             goto err;
 144         /* Force a failure here if the callback returns 1 */
 145         if (OSSL_SELF_TEST_oncorrupt_byte(st, md))
 146             memcpy(md, crngt_glob->crngt_prev, sz);
 147         if (!prov_crngt_compare_previous(crngt_glob->crngt_prev, md, sz)) {
 148             crng_test_pass = 0;
 149             goto err;
 150         }
 151         if (!rand_pool_add(pool, buf, s, s * 8))
 152             goto err;
 153         memcpy(crngt_glob->crngt_prev, md, sz);
 154         t += s;
 155         attempts++;
 156     }
 157     r = t;
 158     *pout = rand_pool_detach(pool);
 159 err:
 160     OSSL_SELF_TEST_onend(st, crng_test_pass);
 161     OSSL_SELF_TEST_free(st);
 162     OPENSSL_cleanse(buf, sizeof(buf));
 163     rand_pool_free(pool);
 164     return r;
 165 }
 166
 167 void prov_crngt_cleanup_entropy(PROV_DRBG *drbg,
 168                                 unsigned char *out, size_t outlen)
 169 {
 170     OPENSSL_secure_clear_free(out, outlen);
 171 }