crypto/rand/rand_lib.c

   1 /*
   2  * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <stdio.h>
  11 #include <time.h>
  12 #include "internal/cryptlib.h"
  13 #include <openssl/opensslconf.h>
  14 #include "internal/rand_int.h"
  15 #include <openssl/engine.h>
  16 #include "internal/thread_once.h"
  17 #include "rand_lcl.h"
  18
  19 #ifndef OPENSSL_NO_ENGINE
  20 /* non-NULL if default_RAND_meth is ENGINE-provided */
  21 static ENGINE *funct_ref;
  22 static CRYPTO_RWLOCK *rand_engine_lock;
  23 #endif
  24 static CRYPTO_RWLOCK *rand_meth_lock;
  25 static const RAND_METHOD *default_RAND_meth;
  26 static CRYPTO_ONCE rand_init = CRYPTO_ONCE_STATIC_INIT;
  27 RAND_BYTES_BUFFER rand_bytes;
  28 int rand_fork_count;
  29
  30 #ifdef OPENSSL_RAND_SEED_RDTSC
  31 /*
  32  * IMPORTANT NOTE:  It is not currently possible to use this code
  33  * because we are not sure about the amount of randomness it provides.
  34  * Some SP900 tests have been run, but there is internal skepticism.
  35  * So for now this code is not used.
  36  */
  37 # error "RDTSC enabled?  Should not be possible!"
  38
  39 /*
  40  * Since we get some randomness from the low-order bits of the
  41  * high-speec clock, it can help.  But don't return a status since
  42  * it's not sufficient to indicate whether or not the seeding was
  43  * done.
  44  */
  45 void rand_read_tsc(RAND_poll_fn cb, void *arg)
  46 {
  47     unsigned char c;
  48     int i;
  49
  50     if ((OPENSSL_ia32cap_P[0] & (1 << 4)) != 0) {
  51         for (i = 0; i < TSC_READ_COUNT; i++) {
  52             c = (unsigned char)(OPENSSL_rdtsc() & 0xFF);
  53             cb(arg, &c, 1, 0.5);
  54         }
  55     }
  56 }
  57 #endif
  58
  59 #ifdef OPENSSL_RAND_SEED_RDCPU
  60 size_t OPENSSL_ia32_rdseed_bytes(char *buf, size_t len);
  61 size_t OPENSSL_ia32_rdrand_bytes(char *buf, size_t len);
  62
  63 extern unsigned int OPENSSL_ia32cap_P[];
  64
  65 int rand_read_cpu(RAND_poll_fn cb, void *arg)
  66 {
  67     char buff[RANDOMNESS_NEEDED];
  68
  69     /* If RDSEED is available, use that. */
  70     if ((OPENSSL_ia32cap_P[2] & (1 << 18)) != 0) {
  71         if (OPENSSL_ia32_rdseed_bytes(buff, sizeof(buff)) == sizeof(buff)) {
  72             cb(arg, buff, (int)sizeof(buff), sizeof(buff));
  73             return 1;
  74         }
  75     }
  76
  77     /* Second choice is RDRAND. */
  78     if ((OPENSSL_ia32cap_P[1] & (1 << (62 - 32))) != 0) {
  79         if (OPENSSL_ia32_rdrand_bytes(buff, sizeof(buff)) == sizeof(buff)) {
  80             cb(arg, buff, (int)sizeof(buff), sizeof(buff));
  81             return 1;
  82         }
  83     }
  84
  85     return 0;
  86 }
  87 #endif
  88
  89
  90 /*
  91  * DRBG has two sets of callbacks; we only discuss the "entropy" one
  92  * here.  When the DRBG needs additional randomness bits (called entropy
  93  * in the NIST document), it calls the get_entropy callback which fills in
  94  * a pointer and returns the number of bytes. When the DRBG is finished with
  95  * the buffer, it calls the cleanup_entropy callback, with the value of
  96  * the buffer that the get_entropy callback filled in.
  97  *
  98  * Get entropy from the system, via RAND_poll if needed.  The |entropy|
  99  * is the bits of randomness required, and is expected to fit into a buffer
 100  * of |min_len|..|max__len| size.  We assume we're getting high-quality
 101  * randomness from the system, and that |min_len| bytes will do.
 102  */
 103 size_t drbg_entropy_from_system(RAND_DRBG *drbg,
 104                                 unsigned char **pout,
 105                                 int entropy, size_t min_len, size_t max_len)
 106 {
 107     int i;
 108
 109
 110     if (min_len > (size_t)drbg->size) {
 111         /* Should not happen.  See comment near RANDOMNESS_NEEDED. */
 112         min_len = drbg->size;
 113     }
 114
 115     if (drbg->filled) {
 116         /* Re-use what we have. */
 117         *pout = drbg->randomness;
 118         return drbg->size;
 119     }
 120
 121     /* If we don't have enough, try to get more. */
 122     CRYPTO_THREAD_write_lock(rand_bytes.lock);
 123     for (i = RAND_POLL_RETRIES; rand_bytes.curr < min_len && --i >= 0; ) {
 124         CRYPTO_THREAD_unlock(rand_bytes.lock);
 125         RAND_poll();
 126         CRYPTO_THREAD_write_lock(rand_bytes.lock);
 127     }
 128
 129     /* Get desired amount, but no more than we have. */
 130     if (min_len > rand_bytes.curr)
 131         min_len = rand_bytes.curr;
 132     if (min_len != 0) {
 133         memcpy(drbg->randomness, rand_bytes.buff, min_len);
 134         drbg->filled = 1;
 135         /* Update amount left and shift it down. */
 136         rand_bytes.curr -= min_len;
 137         if (rand_bytes.curr != 0)
 138             memmove(rand_bytes.buff, &rand_bytes.buff[min_len], rand_bytes.curr);
 139     }
 140     CRYPTO_THREAD_unlock(rand_bytes.lock);
 141     *pout = drbg->randomness;
 142     return min_len;
 143 }
 144
 145 size_t drbg_entropy_from_parent(RAND_DRBG *drbg,
 146                                 unsigned char **pout,
 147                                 int entropy, size_t min_len, size_t max_len)
 148 {
 149     int st;
 150
 151     if (min_len > (size_t)drbg->size) {
 152         /* Should not happen.  See comment near RANDOMNESS_NEEDED. */
 153         min_len = drbg->size;
 154     }
 155
 156     /* Get random from parent, include our state as additional input. */
 157     st = RAND_DRBG_generate(drbg->parent, drbg->randomness, min_len, 0,
 158                             (unsigned char *)drbg, sizeof(*drbg));
 159     if (st == 0)
 160         return 0;
 161     drbg->filled = 1;
 162     *pout = drbg->randomness;
 163     return min_len;
 164 }
 165
 166 void drbg_release_entropy(RAND_DRBG *drbg, unsigned char *out)
 167 {
 168     drbg->filled = 0;
 169     OPENSSL_cleanse(drbg->randomness, drbg->size);
 170 }
 171
 172
 173 /*
 174  * Set up a global DRBG.
 175  */
 176 static int setup_drbg(RAND_DRBG *drbg)
 177 {
 178     int ret = 1;
 179
 180     drbg->lock = CRYPTO_THREAD_lock_new();
 181     ret &= drbg->lock != NULL;
 182     drbg->size = RANDOMNESS_NEEDED;
 183     drbg->secure = CRYPTO_secure_malloc_initialized();
 184     drbg->randomness = drbg->secure
 185         ? OPENSSL_secure_malloc(drbg->size)
 186         : OPENSSL_malloc(drbg->size);
 187     ret &= drbg->randomness != NULL;
 188     /* If you change these parameters, see RANDOMNESS_NEEDED */
 189     ret &= RAND_DRBG_set(drbg,
 190                          NID_aes_128_ctr, RAND_DRBG_FLAG_CTR_USE_DF) == 1;
 191     ret &= RAND_DRBG_set_callbacks(drbg, drbg_entropy_from_system,
 192                                    drbg_release_entropy, NULL, NULL) == 1;
 193     return ret;
 194 }
 195
 196 static void free_drbg(RAND_DRBG *drbg)
 197 {
 198     CRYPTO_THREAD_lock_free(drbg->lock);
 199     if (drbg->secure)
 200         OPENSSL_secure_clear_free(drbg->randomness, drbg->size);
 201     else
 202         OPENSSL_clear_free(drbg->randomness, drbg->size);
 203     RAND_DRBG_uninstantiate(drbg);
 204 }
 205
 206 void rand_fork()
 207 {
 208     rand_fork_count++;
 209 }
 210
 211 DEFINE_RUN_ONCE_STATIC(do_rand_init)
 212 {
 213     int ret = 1;
 214
 215 #ifndef OPENSSL_NO_ENGINE
 216     rand_engine_lock = CRYPTO_THREAD_lock_new();
 217     ret &= rand_engine_lock != NULL;
 218 #endif
 219     rand_meth_lock = CRYPTO_THREAD_lock_new();
 220     ret &= rand_meth_lock != NULL;
 221
 222     rand_bytes.lock = CRYPTO_THREAD_lock_new();
 223     ret &= rand_bytes.lock != NULL;
 224     rand_bytes.curr = 0;
 225     rand_bytes.size = MAX_RANDOMNESS_HELD;
 226     rand_bytes.secure = CRYPTO_secure_malloc_initialized();
 227     rand_bytes.buff = rand_bytes.secure
 228         ? OPENSSL_secure_malloc(rand_bytes.size)
 229         : OPENSSL_malloc(rand_bytes.size);
 230     ret &= rand_bytes.buff != NULL;
 231     ret &= setup_drbg(&rand_drbg);
 232     ret &= setup_drbg(&priv_drbg);
 233     return ret;
 234 }
 235
 236 void rand_cleanup_int(void)
 237 {
 238     const RAND_METHOD *meth = default_RAND_meth;
 239
 240     if (meth != NULL && meth->cleanup != NULL)
 241         meth->cleanup();
 242     RAND_set_rand_method(NULL);
 243 #ifndef OPENSSL_NO_ENGINE
 244     CRYPTO_THREAD_lock_free(rand_engine_lock);
 245 #endif
 246     CRYPTO_THREAD_lock_free(rand_meth_lock);
 247     CRYPTO_THREAD_lock_free(rand_bytes.lock);
 248     if (rand_bytes.secure)
 249         OPENSSL_secure_clear_free(rand_bytes.buff, rand_bytes.size);
 250     else
 251         OPENSSL_clear_free(rand_bytes.buff, rand_bytes.size);
 252     free_drbg(&rand_drbg);
 253     free_drbg(&priv_drbg);
 254 }
 255
 256 /*
 257  * RAND_poll_ex() gets a function pointer to call when it has random bytes.
 258  * RAND_poll() sets the function pointer to be a wrapper that calls RAND_add().
 259  */
 260 static void call_rand_add(void* arg, const void *buf, int num, double r)
 261 {
 262     RAND_add(buf, num, r);
 263 }
 264
 265 int RAND_poll(void)
 266 {
 267     return RAND_poll_ex(call_rand_add, NULL);
 268 }
 269
 270 int RAND_set_rand_method(const RAND_METHOD *meth)
 271 {
 272     if (!RUN_ONCE(&rand_init, do_rand_init))
 273         return 0;
 274
 275     CRYPTO_THREAD_write_lock(rand_meth_lock);
 276 #ifndef OPENSSL_NO_ENGINE
 277     ENGINE_finish(funct_ref);
 278     funct_ref = NULL;
 279 #endif
 280     default_RAND_meth = meth;
 281     CRYPTO_THREAD_unlock(rand_meth_lock);
 282     return 1;
 283 }
 284
 285 const RAND_METHOD *RAND_get_rand_method(void)
 286 {
 287     const RAND_METHOD *tmp_meth = NULL;
 288
 289     if (!RUN_ONCE(&rand_init, do_rand_init))
 290         return NULL;
 291
 292     CRYPTO_THREAD_write_lock(rand_meth_lock);
 293     if (default_RAND_meth == NULL) {
 294 #ifndef OPENSSL_NO_ENGINE
 295         ENGINE *e;
 296
 297         /* If we have an engine that can do RAND, use it. */
 298         if ((e = ENGINE_get_default_RAND()) != NULL
 299                 && (tmp_meth = ENGINE_get_RAND(e)) != NULL) {
 300             funct_ref = e;
 301             default_RAND_meth = tmp_meth;
 302         } else {
 303             ENGINE_finish(e);
 304             default_RAND_meth = &rand_meth;
 305         }
 306 #else
 307         default_RAND_meth = &rand_meth;
 308 #endif
 309     }
 310     tmp_meth = default_RAND_meth;
 311     CRYPTO_THREAD_unlock(rand_meth_lock);
 312     return tmp_meth;
 313 }
 314
 315 #ifndef OPENSSL_NO_ENGINE
 316 int RAND_set_rand_engine(ENGINE *engine)
 317 {
 318     const RAND_METHOD *tmp_meth = NULL;
 319
 320     if (!RUN_ONCE(&rand_init, do_rand_init))
 321         return 0;
 322
 323     if (engine != NULL) {
 324         if (!ENGINE_init(engine))
 325             return 0;
 326         tmp_meth = ENGINE_get_RAND(engine);
 327         if (tmp_meth == NULL) {
 328             ENGINE_finish(engine);
 329             return 0;
 330         }
 331     }
 332     CRYPTO_THREAD_write_lock(rand_engine_lock);
 333     /* This function releases any prior ENGINE so call it first */
 334     RAND_set_rand_method(tmp_meth);
 335     funct_ref = engine;
 336     CRYPTO_THREAD_unlock(rand_engine_lock);
 337     return 1;
 338 }
 339 #endif
 340
 341 void RAND_seed(const void *buf, int num)
 342 {
 343     const RAND_METHOD *meth = RAND_get_rand_method();
 344
 345     if (meth->seed != NULL)
 346         meth->seed(buf, num);
 347 }
 348
 349 void RAND_add(const void *buf, int num, double randomness)
 350 {
 351     const RAND_METHOD *meth = RAND_get_rand_method();
 352
 353     if (meth->add != NULL)
 354         meth->add(buf, num, randomness);
 355 }
 356
 357 /*
 358  * This function is not part of RAND_METHOD, so if we're not using
 359  * the default method, then just call RAND_bytes().  Otherwise make
 360  * sure we're instantiated and use the private DRBG.
 361  */
 362 int RAND_priv_bytes(unsigned char *buf, int num)
 363 {
 364     const RAND_METHOD *meth = RAND_get_rand_method();
 365
 366     if (meth != RAND_OpenSSL())
 367         return RAND_bytes(buf, num);
 368
 369     if (priv_drbg.state == DRBG_UNINITIALISED
 370             && RAND_DRBG_instantiate(&priv_drbg, NULL, 0) == 0)
 371         return 0;
 372     return RAND_DRBG_generate(&priv_drbg, buf, num, 0, NULL, 0);
 373
 374 }
 375
 376 int RAND_bytes(unsigned char *buf, int num)
 377 {
 378     const RAND_METHOD *meth = RAND_get_rand_method();
 379
 380     if (meth->bytes != NULL)
 381         return meth->bytes(buf, num);
 382     RANDerr(RAND_F_RAND_BYTES, RAND_R_FUNC_NOT_IMPLEMENTED);
 383     return -1;
 384 }
 385
 386 #if OPENSSL_API_COMPAT < 0x10100000L
 387 int RAND_pseudo_bytes(unsigned char *buf, int num)
 388 {
 389     const RAND_METHOD *meth = RAND_get_rand_method();
 390
 391     if (meth->pseudorand != NULL)
 392         return meth->pseudorand(buf, num);
 393     return -1;
 394 }
 395 #endif
 396
 397 int RAND_status(void)
 398 {
 399     const RAND_METHOD *meth = RAND_get_rand_method();
 400
 401     if (meth->status != NULL)
 402         return meth->status();
 403     return 0;
 404 }