crypto/rand/rand_lib.c

   1 /*
   2  * Copyright 1995-2017 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_cb rand_add, 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             rand_add(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_cb rand_add, 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             rand_add(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             rand_add(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     unsigned char *randomness;
 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     randomness = drbg->secure ? OPENSSL_secure_malloc(drbg->size)
 116                                     : OPENSSL_malloc(drbg->size);
 117
 118     /* If we don't have enough, try to get more. */
 119     CRYPTO_THREAD_write_lock(rand_bytes.lock);
 120     for (i = RAND_POLL_RETRIES; rand_bytes.curr < min_len && --i >= 0; ) {
 121         CRYPTO_THREAD_unlock(rand_bytes.lock);
 122         RAND_poll();
 123         CRYPTO_THREAD_write_lock(rand_bytes.lock);
 124     }
 125
 126     /* Get desired amount, but no more than we have. */
 127     if (min_len > rand_bytes.curr)
 128         min_len = rand_bytes.curr;
 129     if (min_len != 0) {
 130         memcpy(randomness, rand_bytes.buff, min_len);
 131         /* Update amount left and shift it down. */
 132         rand_bytes.curr -= min_len;
 133         if (rand_bytes.curr != 0)
 134             memmove(rand_bytes.buff, &rand_bytes.buff[min_len], rand_bytes.curr);
 135     }
 136     CRYPTO_THREAD_unlock(rand_bytes.lock);
 137     *pout = randomness;
 138     return min_len;
 139 }
 140
 141 size_t drbg_entropy_from_parent(RAND_DRBG *drbg,
 142                                 unsigned char **pout,
 143                                 int entropy, size_t min_len, size_t max_len)
 144 {
 145     int st;
 146     unsigned char *randomness;
 147
 148     if (min_len > (size_t)drbg->size) {
 149         /* Should not happen.  See comment near RANDOMNESS_NEEDED. */
 150         min_len = drbg->size;
 151     }
 152
 153     randomness = drbg->secure ? OPENSSL_secure_malloc(drbg->size)
 154                                     : OPENSSL_malloc(drbg->size);
 155
 156     /* Get random from parent, include our state as additional input. */
 157     st = RAND_DRBG_generate(drbg->parent, randomness, min_len, 0,
 158                             (unsigned char *)drbg, sizeof(*drbg));
 159     if (st == 0) {
 160         drbg_release_entropy(drbg, randomness, min_len);
 161         return 0;
 162     }
 163     *pout = randomness;
 164     return min_len;
 165 }
 166
 167 void drbg_release_entropy(RAND_DRBG *drbg, unsigned char *out, size_t outlen)
 168 {
 169     if (drbg->secure)
 170         OPENSSL_secure_clear_free(out, outlen);
 171     else
 172         OPENSSL_clear_free(out, outlen);
 173 }
 174
 175
 176 /*
 177  * Set up a global DRBG.
 178  */
 179 static int setup_drbg(RAND_DRBG *drbg)
 180 {
 181     int ret = 1;
 182
 183     drbg->lock = CRYPTO_THREAD_lock_new();
 184     ret &= drbg->lock != NULL;
 185     drbg->size = RANDOMNESS_NEEDED;
 186     drbg->secure = CRYPTO_secure_malloc_initialized();
 187     /* If you change these parameters, see RANDOMNESS_NEEDED */
 188     ret &= RAND_DRBG_set(drbg,
 189                          NID_aes_128_ctr, RAND_DRBG_FLAG_CTR_USE_DF) == 1;
 190     ret &= RAND_DRBG_set_callbacks(drbg, drbg_entropy_from_system,
 191                                    drbg_release_entropy, NULL, NULL) == 1;
 192     return ret;
 193 }
 194
 195 static void free_drbg(RAND_DRBG *drbg)
 196 {
 197     CRYPTO_THREAD_lock_free(drbg->lock);
 198     RAND_DRBG_uninstantiate(drbg);
 199 }
 200
 201 void rand_fork()
 202 {
 203     rand_fork_count++;
 204 }
 205
 206 DEFINE_RUN_ONCE_STATIC(do_rand_init)
 207 {
 208     int ret = 1;
 209
 210 #ifndef OPENSSL_NO_ENGINE
 211     rand_engine_lock = CRYPTO_THREAD_lock_new();
 212     ret &= rand_engine_lock != NULL;
 213 #endif
 214     rand_meth_lock = CRYPTO_THREAD_lock_new();
 215     ret &= rand_meth_lock != NULL;
 216
 217     rand_bytes.lock = CRYPTO_THREAD_lock_new();
 218     ret &= rand_bytes.lock != NULL;
 219     rand_bytes.curr = 0;
 220     rand_bytes.size = MAX_RANDOMNESS_HELD;
 221     rand_bytes.secure = CRYPTO_secure_malloc_initialized();
 222     rand_bytes.buff = rand_bytes.secure
 223         ? OPENSSL_secure_malloc(rand_bytes.size)
 224         : OPENSSL_malloc(rand_bytes.size);
 225     ret &= rand_bytes.buff != NULL;
 226     ret &= setup_drbg(&rand_drbg);
 227     ret &= setup_drbg(&priv_drbg);
 228     return ret;
 229 }
 230
 231 void rand_cleanup_int(void)
 232 {
 233     const RAND_METHOD *meth = default_RAND_meth;
 234
 235     if (meth != NULL && meth->cleanup != NULL)
 236         meth->cleanup();
 237     RAND_set_rand_method(NULL);
 238 #ifndef OPENSSL_NO_ENGINE
 239     CRYPTO_THREAD_lock_free(rand_engine_lock);
 240 #endif
 241     CRYPTO_THREAD_lock_free(rand_meth_lock);
 242     CRYPTO_THREAD_lock_free(rand_bytes.lock);
 243     if (rand_bytes.secure)
 244         OPENSSL_secure_clear_free(rand_bytes.buff, rand_bytes.size);
 245     else
 246         OPENSSL_clear_free(rand_bytes.buff, rand_bytes.size);
 247     free_drbg(&rand_drbg);
 248     free_drbg(&priv_drbg);
 249 }
 250
 251 /*
 252  * RAND_poll_ex() gets a function pointer to call when it has random bytes.
 253  * RAND_poll() sets the function pointer to be a wrapper that calls RAND_add().
 254  */
 255 static void call_rand_add(void* arg, const void *buf, int num, double r)
 256 {
 257     RAND_add(buf, num, r);
 258 }
 259
 260 int RAND_poll(void)
 261 {
 262     return RAND_poll_ex(call_rand_add, NULL);
 263 }
 264
 265 int RAND_set_rand_method(const RAND_METHOD *meth)
 266 {
 267     if (!RUN_ONCE(&rand_init, do_rand_init))
 268         return 0;
 269
 270     CRYPTO_THREAD_write_lock(rand_meth_lock);
 271 #ifndef OPENSSL_NO_ENGINE
 272     ENGINE_finish(funct_ref);
 273     funct_ref = NULL;
 274 #endif
 275     default_RAND_meth = meth;
 276     CRYPTO_THREAD_unlock(rand_meth_lock);
 277     return 1;
 278 }
 279
 280 const RAND_METHOD *RAND_get_rand_method(void)
 281 {
 282     const RAND_METHOD *tmp_meth = NULL;
 283
 284     if (!RUN_ONCE(&rand_init, do_rand_init))
 285         return NULL;
 286
 287     CRYPTO_THREAD_write_lock(rand_meth_lock);
 288     if (default_RAND_meth == NULL) {
 289 #ifndef OPENSSL_NO_ENGINE
 290         ENGINE *e;
 291
 292         /* If we have an engine that can do RAND, use it. */
 293         if ((e = ENGINE_get_default_RAND()) != NULL
 294                 && (tmp_meth = ENGINE_get_RAND(e)) != NULL) {
 295             funct_ref = e;
 296             default_RAND_meth = tmp_meth;
 297         } else {
 298             ENGINE_finish(e);
 299             default_RAND_meth = &rand_meth;
 300         }
 301 #else
 302         default_RAND_meth = &rand_meth;
 303 #endif
 304     }
 305     tmp_meth = default_RAND_meth;
 306     CRYPTO_THREAD_unlock(rand_meth_lock);
 307     return tmp_meth;
 308 }
 309
 310 #ifndef OPENSSL_NO_ENGINE
 311 int RAND_set_rand_engine(ENGINE *engine)
 312 {
 313     const RAND_METHOD *tmp_meth = NULL;
 314
 315     if (!RUN_ONCE(&rand_init, do_rand_init))
 316         return 0;
 317
 318     if (engine != NULL) {
 319         if (!ENGINE_init(engine))
 320             return 0;
 321         tmp_meth = ENGINE_get_RAND(engine);
 322         if (tmp_meth == NULL) {
 323             ENGINE_finish(engine);
 324             return 0;
 325         }
 326     }
 327     CRYPTO_THREAD_write_lock(rand_engine_lock);
 328     /* This function releases any prior ENGINE so call it first */
 329     RAND_set_rand_method(tmp_meth);
 330     funct_ref = engine;
 331     CRYPTO_THREAD_unlock(rand_engine_lock);
 332     return 1;
 333 }
 334 #endif
 335
 336 void RAND_seed(const void *buf, int num)
 337 {
 338     const RAND_METHOD *meth = RAND_get_rand_method();
 339
 340     if (meth->seed != NULL)
 341         meth->seed(buf, num);
 342 }
 343
 344 void RAND_add(const void *buf, int num, double randomness)
 345 {
 346     const RAND_METHOD *meth = RAND_get_rand_method();
 347
 348     if (meth->add != NULL)
 349         meth->add(buf, num, randomness);
 350 }
 351
 352 /*
 353  * This function is not part of RAND_METHOD, so if we're not using
 354  * the default method, then just call RAND_bytes().  Otherwise make
 355  * sure we're instantiated and use the private DRBG.
 356  */
 357 int RAND_priv_bytes(unsigned char *buf, int num)
 358 {
 359     const RAND_METHOD *meth = RAND_get_rand_method();
 360
 361     if (meth != RAND_OpenSSL())
 362         return RAND_bytes(buf, num);
 363
 364     if (priv_drbg.state == DRBG_UNINITIALISED
 365             && RAND_DRBG_instantiate(&priv_drbg, NULL, 0) == 0)
 366         return 0;
 367     return RAND_DRBG_generate(&priv_drbg, buf, num, 0, NULL, 0);
 368
 369 }
 370
 371 int RAND_bytes(unsigned char *buf, int num)
 372 {
 373     const RAND_METHOD *meth = RAND_get_rand_method();
 374
 375     if (meth->bytes != NULL)
 376         return meth->bytes(buf, num);
 377     RANDerr(RAND_F_RAND_BYTES, RAND_R_FUNC_NOT_IMPLEMENTED);
 378     return -1;
 379 }
 380
 381 #if OPENSSL_API_COMPAT < 0x10100000L
 382 int RAND_pseudo_bytes(unsigned char *buf, int num)
 383 {
 384     const RAND_METHOD *meth = RAND_get_rand_method();
 385
 386     if (meth->pseudorand != NULL)
 387         return meth->pseudorand(buf, num);
 388     return -1;
 389 }
 390 #endif
 391
 392 int RAND_status(void)
 393 {
 394     const RAND_METHOD *meth = RAND_get_rand_method();
 395
 396     if (meth->status != NULL)
 397         return meth->status();
 398     return 0;
 399 }