2cfa4f5b8c8b626a4134284a55c60d65e225faae
[openssl.git] / crypto / rand / drbg_lib.c
1 /*
2  * Copyright 2011-2018 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 <string.h>
11 #include <openssl/crypto.h>
12 #include <openssl/err.h>
13 #include <openssl/rand.h>
14 #include "rand_lcl.h"
15 #include "internal/thread_once.h"
16 #include "internal/rand_int.h"
17 #include "internal/cryptlib_int.h"
18
19 /*
20  * Support framework for NIST SP 800-90A DRBG
21  *
22  * See manual page RAND_DRBG(7) for a general overview.
23  *
24  * The OpenSSL model is to have new and free functions, and that new
25  * does all initialization.  That is not the NIST model, which has
26  * instantiation and un-instantiate, and re-use within a new/free
27  * lifecycle.  (No doubt this comes from the desire to support hardware
28  * DRBG, where allocation of resources on something like an HSM is
29  * a much bigger deal than just re-setting an allocated resource.)
30  */
31
32 /*
33  * The three shared DRBG instances
34  *
35  * There are three shared DRBG instances: <master>, <public>, and <private>.
36  */
37
38 /*
39  * The <master> DRBG
40  *
41  * Not used directly by the application, only for reseeding the two other
42  * DRBGs. It reseeds itself by pulling either randomness from os entropy
43  * sources or by consuming randomness which was added by RAND_add().
44  *
45  * The <master> DRBG is a global instance which is accessed concurrently by
46  * all threads. The necessary locking is managed automatically by its child
47  * DRBG instances during reseeding.
48  */
49 static RAND_DRBG *master_drbg;
50 /*
51  * The <public> DRBG
52  *
53  * Used by default for generating random bytes using RAND_bytes().
54  *
55  * The <public> DRBG is thread-local, i.e., there is one instance per thread.
56  */
57 static CRYPTO_THREAD_LOCAL public_drbg;
58 /*
59  * The <private> DRBG
60  *
61  * Used by default for generating private keys using RAND_priv_bytes()
62  *
63  * The <private> DRBG is thread-local, i.e., there is one instance per thread.
64  */
65 static CRYPTO_THREAD_LOCAL private_drbg;
66
67
68
69 /* NIST SP 800-90A DRBG recommends the use of a personalization string. */
70 static const char ossl_pers_string[] = "OpenSSL NIST SP 800-90A DRBG";
71
72 static CRYPTO_ONCE rand_drbg_init = CRYPTO_ONCE_STATIC_INIT;
73
74
75 #define RAND_DRBG_TYPE_FLAGS    ( \
76     RAND_DRBG_FLAG_MASTER | RAND_DRBG_FLAG_PUBLIC | RAND_DRBG_FLAG_PRIVATE )
77
78 #define RAND_DRBG_TYPE_MASTER                     0
79 #define RAND_DRBG_TYPE_PUBLIC                     1
80 #define RAND_DRBG_TYPE_PRIVATE                    2
81
82 /* Defaults */
83 static int rand_drbg_type[3] = {
84     RAND_DRBG_TYPE, /* Master */
85     RAND_DRBG_TYPE, /* Public */
86     RAND_DRBG_TYPE  /* Private */
87 };
88 static unsigned int rand_drbg_flags[3] = {
89     RAND_DRBG_FLAGS | RAND_DRBG_FLAG_MASTER, /* Master */
90     RAND_DRBG_FLAGS | RAND_DRBG_FLAG_PUBLIC, /* Public */
91     RAND_DRBG_FLAGS | RAND_DRBG_FLAG_PRIVATE /* Private */
92 };
93
94 static unsigned int master_reseed_interval = MASTER_RESEED_INTERVAL;
95 static unsigned int slave_reseed_interval  = SLAVE_RESEED_INTERVAL;
96
97 static time_t master_reseed_time_interval = MASTER_RESEED_TIME_INTERVAL;
98 static time_t slave_reseed_time_interval  = SLAVE_RESEED_TIME_INTERVAL;
99
100 /* A logical OR of all used DRBG flag bits (currently there is only one) */
101 static const unsigned int rand_drbg_used_flags =
102     RAND_DRBG_FLAG_CTR_NO_DF | RAND_DRBG_FLAG_HMAC | RAND_DRBG_TYPE_FLAGS;
103
104
105 static RAND_DRBG *drbg_setup(RAND_DRBG *parent, int drbg_type);
106
107 static RAND_DRBG *rand_drbg_new(int secure,
108                                 int type,
109                                 unsigned int flags,
110                                 RAND_DRBG *parent);
111
112 static int is_ctr(int type)
113 {
114     switch (type) {
115     case NID_aes_128_ctr:
116     case NID_aes_192_ctr:
117     case NID_aes_256_ctr:
118         return 1;
119     default:
120         return 0;
121     }
122 }
123
124 static int is_digest(int type)
125 {
126     switch (type) {
127     case NID_sha1:
128     case NID_sha224:
129     case NID_sha256:
130     case NID_sha384:
131     case NID_sha512:
132     case NID_sha512_224:
133     case NID_sha512_256:
134     case NID_sha3_224:
135     case NID_sha3_256:
136     case NID_sha3_384:
137     case NID_sha3_512:
138         return 1;
139     default:
140         return 0;
141     }
142 }
143
144 /*
145  * Set/initialize |drbg| to be of type |type|, with optional |flags|.
146  *
147  * If |type| and |flags| are zero, use the defaults
148  *
149  * Returns 1 on success, 0 on failure.
150  */
151 int RAND_DRBG_set(RAND_DRBG *drbg, int type, unsigned int flags)
152 {
153     int ret = 1;
154
155     if (type == 0 && flags == 0) {
156         type = rand_drbg_type[RAND_DRBG_TYPE_MASTER];
157         flags = rand_drbg_flags[RAND_DRBG_TYPE_MASTER];
158     }
159
160     /* If set is called multiple times - clear the old one */
161     if (drbg->type != 0 && (type != drbg->type || flags != drbg->flags)) {
162         drbg->meth->uninstantiate(drbg);
163         rand_pool_free(drbg->adin_pool);
164         drbg->adin_pool = NULL;
165     }
166
167     drbg->state = DRBG_UNINITIALISED;
168     drbg->flags = flags;
169     drbg->type = type;
170
171     if (type == 0) {
172         /* Uninitialized; that's okay. */
173         drbg->meth = NULL;
174         return 1;
175     } else if (is_ctr(type)) {
176         ret = drbg_ctr_init(drbg);
177     } else if (is_digest(type)) {
178         if (flags & RAND_DRBG_FLAG_HMAC)
179             ret = drbg_hmac_init(drbg);
180         else
181             ret = drbg_hash_init(drbg);
182     } else {
183         drbg->type = 0;
184         drbg->flags = 0;
185         drbg->meth = NULL;
186         RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_UNSUPPORTED_DRBG_TYPE);
187         return 0;
188     }
189
190     if (ret == 0) {
191         drbg->state = DRBG_ERROR;
192         RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_ERROR_INITIALISING_DRBG);
193     }
194     return ret;
195 }
196
197 /*
198  * Set/initialize default |type| and |flag| for new drbg instances.
199  *
200  * Returns 1 on success, 0 on failure.
201  */
202 int RAND_DRBG_set_defaults(int type, unsigned int flags)
203 {
204     int all;
205     if (!(is_digest(type) || is_ctr(type))) {
206         RANDerr(RAND_F_RAND_DRBG_SET_DEFAULTS, RAND_R_UNSUPPORTED_DRBG_TYPE);
207         return 0;
208     }
209
210     if ((flags & ~rand_drbg_used_flags) != 0) {
211         RANDerr(RAND_F_RAND_DRBG_SET_DEFAULTS, RAND_R_UNSUPPORTED_DRBG_FLAGS);
212         return 0;
213     }
214
215     all = ((flags & RAND_DRBG_TYPE_FLAGS) == 0);
216     if (all || (flags & RAND_DRBG_FLAG_MASTER) != 0) {
217         rand_drbg_type[RAND_DRBG_TYPE_MASTER] = type;
218         rand_drbg_flags[RAND_DRBG_TYPE_MASTER] = flags | RAND_DRBG_FLAG_MASTER;
219     }
220     if (all || (flags & RAND_DRBG_FLAG_PUBLIC) != 0) {
221         rand_drbg_type[RAND_DRBG_TYPE_PUBLIC]  = type;
222         rand_drbg_flags[RAND_DRBG_TYPE_PUBLIC] = flags | RAND_DRBG_FLAG_PUBLIC;
223     }
224     if (all || (flags & RAND_DRBG_FLAG_PRIVATE) != 0) {
225         rand_drbg_type[RAND_DRBG_TYPE_PRIVATE] = type;
226         rand_drbg_flags[RAND_DRBG_TYPE_PRIVATE] = flags | RAND_DRBG_FLAG_PRIVATE;
227     }
228     return 1;
229 }
230
231
232 /*
233  * Allocate memory and initialize a new DRBG. The DRBG is allocated on
234  * the secure heap if |secure| is nonzero and the secure heap is enabled.
235  * The |parent|, if not NULL, will be used as random source for reseeding.
236  *
237  * Returns a pointer to the new DRBG instance on success, NULL on failure.
238  */
239 static RAND_DRBG *rand_drbg_new(int secure,
240                                 int type,
241                                 unsigned int flags,
242                                 RAND_DRBG *parent)
243 {
244     RAND_DRBG *drbg = secure ?
245         OPENSSL_secure_zalloc(sizeof(*drbg)) : OPENSSL_zalloc(sizeof(*drbg));
246
247     if (drbg == NULL) {
248         RANDerr(RAND_F_RAND_DRBG_NEW, ERR_R_MALLOC_FAILURE);
249         return NULL;
250     }
251
252     drbg->secure = secure && CRYPTO_secure_allocated(drbg);
253     drbg->fork_count = rand_fork_count;
254     drbg->parent = parent;
255
256     if (parent == NULL) {
257         drbg->get_entropy = rand_drbg_get_entropy;
258         drbg->cleanup_entropy = rand_drbg_cleanup_entropy;
259 #ifndef RAND_DRBG_GET_RANDOM_NONCE
260         drbg->get_nonce = rand_drbg_get_nonce;
261         drbg->cleanup_nonce = rand_drbg_cleanup_nonce;
262 #endif
263
264         drbg->reseed_interval = master_reseed_interval;
265         drbg->reseed_time_interval = master_reseed_time_interval;
266     } else {
267         drbg->get_entropy = rand_drbg_get_entropy;
268         drbg->cleanup_entropy = rand_drbg_cleanup_entropy;
269         /*
270          * Do not provide nonce callbacks, the child DRBGs will
271          * obtain their nonce using random bits from the parent.
272          */
273
274         drbg->reseed_interval = slave_reseed_interval;
275         drbg->reseed_time_interval = slave_reseed_time_interval;
276     }
277
278     if (RAND_DRBG_set(drbg, type, flags) == 0)
279         goto err;
280
281     if (parent != NULL) {
282         rand_drbg_lock(parent);
283         if (drbg->strength > parent->strength) {
284             /*
285              * We currently don't support the algorithm from NIST SP 800-90C
286              * 10.1.2 to use a weaker DRBG as source
287              */
288             rand_drbg_unlock(parent);
289             RANDerr(RAND_F_RAND_DRBG_NEW, RAND_R_PARENT_STRENGTH_TOO_WEAK);
290             goto err;
291         }
292         rand_drbg_unlock(parent);
293     }
294
295     return drbg;
296
297  err:
298     RAND_DRBG_free(drbg);
299
300     return NULL;
301 }
302
303 RAND_DRBG *RAND_DRBG_new(int type, unsigned int flags, RAND_DRBG *parent)
304 {
305     return rand_drbg_new(0, type, flags, parent);
306 }
307
308 RAND_DRBG *RAND_DRBG_secure_new(int type, unsigned int flags, RAND_DRBG *parent)
309 {
310     return rand_drbg_new(1, type, flags, parent);
311 }
312
313 /*
314  * Uninstantiate |drbg| and free all memory.
315  */
316 void RAND_DRBG_free(RAND_DRBG *drbg)
317 {
318     if (drbg == NULL)
319         return;
320
321     if (drbg->meth != NULL)
322         drbg->meth->uninstantiate(drbg);
323     rand_pool_free(drbg->adin_pool);
324     CRYPTO_THREAD_lock_free(drbg->lock);
325     CRYPTO_free_ex_data(CRYPTO_EX_INDEX_DRBG, drbg, &drbg->ex_data);
326
327     if (drbg->secure)
328         OPENSSL_secure_clear_free(drbg, sizeof(*drbg));
329     else
330         OPENSSL_clear_free(drbg, sizeof(*drbg));
331 }
332
333 /*
334  * Instantiate |drbg|, after it has been initialized.  Use |pers| and
335  * |perslen| as prediction-resistance input.
336  *
337  * Requires that drbg->lock is already locked for write, if non-null.
338  *
339  * Returns 1 on success, 0 on failure.
340  */
341 int RAND_DRBG_instantiate(RAND_DRBG *drbg,
342                           const unsigned char *pers, size_t perslen)
343 {
344     unsigned char *nonce = NULL, *entropy = NULL;
345     size_t noncelen = 0, entropylen = 0;
346     size_t min_entropy = drbg->strength;
347     size_t min_entropylen = drbg->min_entropylen;
348     size_t max_entropylen = drbg->max_entropylen;
349
350     if (perslen > drbg->max_perslen) {
351         RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
352                 RAND_R_PERSONALISATION_STRING_TOO_LONG);
353         goto end;
354     }
355
356     if (drbg->meth == NULL) {
357         RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
358                 RAND_R_NO_DRBG_IMPLEMENTATION_SELECTED);
359         goto end;
360     }
361
362     if (drbg->state != DRBG_UNINITIALISED) {
363         RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
364                 drbg->state == DRBG_ERROR ? RAND_R_IN_ERROR_STATE
365                                           : RAND_R_ALREADY_INSTANTIATED);
366         goto end;
367     }
368
369     drbg->state = DRBG_ERROR;
370
371     /*
372      * NIST SP800-90Ar1 section 9.1 says you can combine getting the entropy
373      * and nonce in 1 call by increasing the entropy with 50% and increasing
374      * the minimum length to accomadate the length of the nonce.
375      * We do this in case a nonce is require and get_nonce is NULL.
376      */
377     if (drbg->min_noncelen > 0 && drbg->get_nonce == NULL) {
378         min_entropy += drbg->strength / 2;
379         min_entropylen += drbg->min_noncelen;
380         max_entropylen += drbg->max_noncelen;
381     }
382
383     drbg->reseed_next_counter = tsan_load(&drbg->reseed_prop_counter);
384     if (drbg->reseed_next_counter) {
385         drbg->reseed_next_counter++;
386         if(!drbg->reseed_next_counter)
387             drbg->reseed_next_counter = 1;
388     }
389
390     if (drbg->get_entropy != NULL)
391         entropylen = drbg->get_entropy(drbg, &entropy, min_entropy,
392                                        min_entropylen, max_entropylen, 0);
393     if (entropylen < min_entropylen
394             || entropylen > max_entropylen) {
395         RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_ENTROPY);
396         goto end;
397     }
398
399     if (drbg->min_noncelen > 0 && drbg->get_nonce != NULL) {
400         noncelen = drbg->get_nonce(drbg, &nonce, drbg->strength / 2,
401                                    drbg->min_noncelen, drbg->max_noncelen);
402         if (noncelen < drbg->min_noncelen || noncelen > drbg->max_noncelen) {
403             RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_NONCE);
404             goto end;
405         }
406     }
407
408     if (!drbg->meth->instantiate(drbg, entropy, entropylen,
409                          nonce, noncelen, pers, perslen)) {
410         RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_INSTANTIATING_DRBG);
411         goto end;
412     }
413
414     drbg->state = DRBG_READY;
415     drbg->reseed_gen_counter = 1;
416     drbg->reseed_time = time(NULL);
417     tsan_store(&drbg->reseed_prop_counter, drbg->reseed_next_counter);
418
419  end:
420     if (entropy != NULL && drbg->cleanup_entropy != NULL)
421         drbg->cleanup_entropy(drbg, entropy, entropylen);
422     if (nonce != NULL && drbg->cleanup_nonce != NULL)
423         drbg->cleanup_nonce(drbg, nonce, noncelen);
424     if (drbg->state == DRBG_READY)
425         return 1;
426     return 0;
427 }
428
429 /*
430  * Uninstantiate |drbg|. Must be instantiated before it can be used.
431  *
432  * Requires that drbg->lock is already locked for write, if non-null.
433  *
434  * Returns 1 on success, 0 on failure.
435  */
436 int RAND_DRBG_uninstantiate(RAND_DRBG *drbg)
437 {
438     int index = -1, type, flags;
439     if (drbg->meth == NULL) {
440         drbg->state = DRBG_ERROR;
441         RANDerr(RAND_F_RAND_DRBG_UNINSTANTIATE,
442                 RAND_R_NO_DRBG_IMPLEMENTATION_SELECTED);
443         return 0;
444     }
445
446     /* Clear the entire drbg->ctr struct, then reset some important
447      * members of the drbg->ctr struct (e.g. keysize, df_ks) to their
448      * initial values.
449      */
450     drbg->meth->uninstantiate(drbg);
451
452     /* The reset uses the default values for type and flags */
453     if (drbg->flags & RAND_DRBG_FLAG_MASTER)
454         index = RAND_DRBG_TYPE_MASTER;
455     else if (drbg->flags & RAND_DRBG_FLAG_PRIVATE)
456         index = RAND_DRBG_TYPE_PRIVATE;
457     else if (drbg->flags & RAND_DRBG_FLAG_PUBLIC)
458         index = RAND_DRBG_TYPE_PUBLIC;
459
460     if (index != -1) {
461         flags = rand_drbg_flags[index];
462         type = rand_drbg_type[index];
463     } else {
464         flags = drbg->flags;
465         type = drbg->type;
466     }
467     return RAND_DRBG_set(drbg, type, flags);
468 }
469
470 /*
471  * Reseed |drbg|, mixing in the specified data
472  *
473  * Requires that drbg->lock is already locked for write, if non-null.
474  *
475  * Returns 1 on success, 0 on failure.
476  */
477 int RAND_DRBG_reseed(RAND_DRBG *drbg,
478                      const unsigned char *adin, size_t adinlen,
479                      int prediction_resistance)
480 {
481     unsigned char *entropy = NULL;
482     size_t entropylen = 0;
483
484     if (drbg->state == DRBG_ERROR) {
485         RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_IN_ERROR_STATE);
486         return 0;
487     }
488     if (drbg->state == DRBG_UNINITIALISED) {
489         RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_NOT_INSTANTIATED);
490         return 0;
491     }
492
493     if (adin == NULL) {
494         adinlen = 0;
495     } else if (adinlen > drbg->max_adinlen) {
496         RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
497         return 0;
498     }
499
500     drbg->state = DRBG_ERROR;
501
502     drbg->reseed_next_counter = tsan_load(&drbg->reseed_prop_counter);
503     if (drbg->reseed_next_counter) {
504         drbg->reseed_next_counter++;
505         if(!drbg->reseed_next_counter)
506             drbg->reseed_next_counter = 1;
507     }
508
509     if (drbg->get_entropy != NULL)
510         entropylen = drbg->get_entropy(drbg, &entropy, drbg->strength,
511                                        drbg->min_entropylen,
512                                        drbg->max_entropylen,
513                                        prediction_resistance);
514     if (entropylen < drbg->min_entropylen
515             || entropylen > drbg->max_entropylen) {
516         RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ERROR_RETRIEVING_ENTROPY);
517         goto end;
518     }
519
520     if (!drbg->meth->reseed(drbg, entropy, entropylen, adin, adinlen))
521         goto end;
522
523     drbg->state = DRBG_READY;
524     drbg->reseed_gen_counter = 1;
525     drbg->reseed_time = time(NULL);
526     tsan_store(&drbg->reseed_prop_counter, drbg->reseed_next_counter);
527
528  end:
529     if (entropy != NULL && drbg->cleanup_entropy != NULL)
530         drbg->cleanup_entropy(drbg, entropy, entropylen);
531     if (drbg->state == DRBG_READY)
532         return 1;
533     return 0;
534 }
535
536 /*
537  * Restart |drbg|, using the specified entropy or additional input
538  *
539  * Tries its best to get the drbg instantiated by all means,
540  * regardless of its current state.
541  *
542  * Optionally, a |buffer| of |len| random bytes can be passed,
543  * which is assumed to contain at least |entropy| bits of entropy.
544  *
545  * If |entropy| > 0, the buffer content is used as entropy input.
546  *
547  * If |entropy| == 0, the buffer content is used as additional input
548  *
549  * Returns 1 on success, 0 on failure.
550  *
551  * This function is used internally only.
552  */
553 int rand_drbg_restart(RAND_DRBG *drbg,
554                       const unsigned char *buffer, size_t len, size_t entropy)
555 {
556     int reseeded = 0;
557     const unsigned char *adin = NULL;
558     size_t adinlen = 0;
559
560     if (drbg->pool != NULL) {
561         RANDerr(RAND_F_RAND_DRBG_RESTART, ERR_R_INTERNAL_ERROR);
562         drbg->state = DRBG_ERROR;
563         rand_pool_free(drbg->pool);
564         drbg->pool = NULL;
565         return 0;
566     }
567
568     if (buffer != NULL) {
569         if (entropy > 0) {
570             if (drbg->max_entropylen < len) {
571                 RANDerr(RAND_F_RAND_DRBG_RESTART,
572                     RAND_R_ENTROPY_INPUT_TOO_LONG);
573                 drbg->state = DRBG_ERROR;
574                 return 0;
575             }
576
577             if (entropy > 8 * len) {
578                 RANDerr(RAND_F_RAND_DRBG_RESTART, RAND_R_ENTROPY_OUT_OF_RANGE);
579                 drbg->state = DRBG_ERROR;
580                 return 0;
581             }
582
583             /* will be picked up by the rand_drbg_get_entropy() callback */
584             drbg->pool = rand_pool_attach(buffer, len, entropy);
585             if (drbg->pool == NULL)
586                 return 0;
587         } else {
588             if (drbg->max_adinlen < len) {
589                 RANDerr(RAND_F_RAND_DRBG_RESTART,
590                         RAND_R_ADDITIONAL_INPUT_TOO_LONG);
591                 drbg->state = DRBG_ERROR;
592                 return 0;
593             }
594             adin = buffer;
595             adinlen = len;
596         }
597     }
598
599     /* repair error state */
600     if (drbg->state == DRBG_ERROR)
601         RAND_DRBG_uninstantiate(drbg);
602
603     /* repair uninitialized state */
604     if (drbg->state == DRBG_UNINITIALISED) {
605         /* reinstantiate drbg */
606         RAND_DRBG_instantiate(drbg,
607                               (const unsigned char *) ossl_pers_string,
608                               sizeof(ossl_pers_string) - 1);
609         /* already reseeded. prevent second reseeding below */
610         reseeded = (drbg->state == DRBG_READY);
611     }
612
613     /* refresh current state if entropy or additional input has been provided */
614     if (drbg->state == DRBG_READY) {
615         if (adin != NULL) {
616             /*
617              * mix in additional input without reseeding
618              *
619              * Similar to RAND_DRBG_reseed(), but the provided additional
620              * data |adin| is mixed into the current state without pulling
621              * entropy from the trusted entropy source using get_entropy().
622              * This is not a reseeding in the strict sense of NIST SP 800-90A.
623              */
624             drbg->meth->reseed(drbg, adin, adinlen, NULL, 0);
625         } else if (reseeded == 0) {
626             /* do a full reseeding if it has not been done yet above */
627             RAND_DRBG_reseed(drbg, NULL, 0, 0);
628         }
629     }
630
631     rand_pool_free(drbg->pool);
632     drbg->pool = NULL;
633
634     return drbg->state == DRBG_READY;
635 }
636
637 /*
638  * Generate |outlen| bytes into the buffer at |out|.  Reseed if we need
639  * to or if |prediction_resistance| is set.  Additional input can be
640  * sent in |adin| and |adinlen|.
641  *
642  * Requires that drbg->lock is already locked for write, if non-null.
643  *
644  * Returns 1 on success, 0 on failure.
645  *
646  */
647 int RAND_DRBG_generate(RAND_DRBG *drbg, unsigned char *out, size_t outlen,
648                        int prediction_resistance,
649                        const unsigned char *adin, size_t adinlen)
650 {
651     int reseed_required = 0;
652
653     if (drbg->state != DRBG_READY) {
654         /* try to recover from previous errors */
655         rand_drbg_restart(drbg, NULL, 0, 0);
656
657         if (drbg->state == DRBG_ERROR) {
658             RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_IN_ERROR_STATE);
659             return 0;
660         }
661         if (drbg->state == DRBG_UNINITIALISED) {
662             RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_NOT_INSTANTIATED);
663             return 0;
664         }
665     }
666
667     if (outlen > drbg->max_request) {
668         RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_REQUEST_TOO_LARGE_FOR_DRBG);
669         return 0;
670     }
671     if (adinlen > drbg->max_adinlen) {
672         RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
673         return 0;
674     }
675
676     if (drbg->fork_count != rand_fork_count) {
677         drbg->fork_count = rand_fork_count;
678         reseed_required = 1;
679     }
680
681     if (drbg->reseed_interval > 0) {
682         if (drbg->reseed_gen_counter > drbg->reseed_interval)
683             reseed_required = 1;
684     }
685     if (drbg->reseed_time_interval > 0) {
686         time_t now = time(NULL);
687         if (now < drbg->reseed_time
688             || now - drbg->reseed_time >= drbg->reseed_time_interval)
689             reseed_required = 1;
690     }
691     if (drbg->parent != NULL) {
692         unsigned int reseed_counter = tsan_load(&drbg->reseed_prop_counter);
693         if (reseed_counter > 0
694                 && tsan_load(&drbg->parent->reseed_prop_counter)
695                    != reseed_counter)
696             reseed_required = 1;
697     }
698
699     if (reseed_required || prediction_resistance) {
700         if (!RAND_DRBG_reseed(drbg, adin, adinlen, prediction_resistance)) {
701             RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_RESEED_ERROR);
702             return 0;
703         }
704         adin = NULL;
705         adinlen = 0;
706     }
707
708     if (!drbg->meth->generate(drbg, out, outlen, adin, adinlen)) {
709         drbg->state = DRBG_ERROR;
710         RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_GENERATE_ERROR);
711         return 0;
712     }
713
714     drbg->reseed_gen_counter++;
715
716     return 1;
717 }
718
719 /*
720  * Generates |outlen| random bytes and stores them in |out|. It will
721  * using the given |drbg| to generate the bytes.
722  *
723  * Requires that drbg->lock is already locked for write, if non-null.
724  *
725  * Returns 1 on success 0 on failure.
726  */
727 int RAND_DRBG_bytes(RAND_DRBG *drbg, unsigned char *out, size_t outlen)
728 {
729     unsigned char *additional = NULL;
730     size_t additional_len;
731     size_t chunk;
732     size_t ret = 0;
733
734     if (drbg->adin_pool == NULL) {
735         if (drbg->type == 0)
736             goto err;
737         drbg->adin_pool = rand_pool_new(0, 0, drbg->max_adinlen);
738         if (drbg->adin_pool == NULL)
739             goto err;
740     }
741
742     additional_len = rand_drbg_get_additional_data(drbg->adin_pool,
743                                                    &additional);
744
745     for ( ; outlen > 0; outlen -= chunk, out += chunk) {
746         chunk = outlen;
747         if (chunk > drbg->max_request)
748             chunk = drbg->max_request;
749         ret = RAND_DRBG_generate(drbg, out, chunk, 0, additional, additional_len);
750         if (!ret)
751             goto err;
752     }
753     ret = 1;
754
755  err:
756     if (additional != NULL)
757         rand_drbg_cleanup_additional_data(drbg->adin_pool, additional);
758
759     return ret;
760 }
761
762 /*
763  * Set the RAND_DRBG callbacks for obtaining entropy and nonce.
764  *
765  * Setting the callbacks is allowed only if the drbg has not been
766  * initialized yet. Otherwise, the operation will fail.
767  *
768  * Returns 1 on success, 0 on failure.
769  */
770 int RAND_DRBG_set_callbacks(RAND_DRBG *drbg,
771                             RAND_DRBG_get_entropy_fn get_entropy,
772                             RAND_DRBG_cleanup_entropy_fn cleanup_entropy,
773                             RAND_DRBG_get_nonce_fn get_nonce,
774                             RAND_DRBG_cleanup_nonce_fn cleanup_nonce)
775 {
776     if (drbg->state != DRBG_UNINITIALISED
777             || drbg->parent != NULL)
778         return 0;
779     drbg->get_entropy = get_entropy;
780     drbg->cleanup_entropy = cleanup_entropy;
781     drbg->get_nonce = get_nonce;
782     drbg->cleanup_nonce = cleanup_nonce;
783     return 1;
784 }
785
786 /*
787  * Set the reseed interval.
788  *
789  * The drbg will reseed automatically whenever the number of generate
790  * requests exceeds the given reseed interval. If the reseed interval
791  * is 0, then this feature is disabled.
792  *
793  * Returns 1 on success, 0 on failure.
794  */
795 int RAND_DRBG_set_reseed_interval(RAND_DRBG *drbg, unsigned int interval)
796 {
797     if (interval > MAX_RESEED_INTERVAL)
798         return 0;
799     drbg->reseed_interval = interval;
800     return 1;
801 }
802
803 /*
804  * Set the reseed time interval.
805  *
806  * The drbg will reseed automatically whenever the time elapsed since
807  * the last reseeding exceeds the given reseed time interval. For safety,
808  * a reseeding will also occur if the clock has been reset to a smaller
809  * value.
810  *
811  * Returns 1 on success, 0 on failure.
812  */
813 int RAND_DRBG_set_reseed_time_interval(RAND_DRBG *drbg, time_t interval)
814 {
815     if (interval > MAX_RESEED_TIME_INTERVAL)
816         return 0;
817     drbg->reseed_time_interval = interval;
818     return 1;
819 }
820
821 /*
822  * Set the default values for reseed (time) intervals of new DRBG instances
823  *
824  * The default values can be set independently for master DRBG instances
825  * (without a parent) and slave DRBG instances (with parent).
826  *
827  * Returns 1 on success, 0 on failure.
828  */
829
830 int RAND_DRBG_set_reseed_defaults(
831                                   unsigned int _master_reseed_interval,
832                                   unsigned int _slave_reseed_interval,
833                                   time_t _master_reseed_time_interval,
834                                   time_t _slave_reseed_time_interval
835                                   )
836 {
837     if (_master_reseed_interval > MAX_RESEED_INTERVAL
838         || _slave_reseed_interval > MAX_RESEED_INTERVAL)
839         return 0;
840
841     if (_master_reseed_time_interval > MAX_RESEED_TIME_INTERVAL
842         || _slave_reseed_time_interval > MAX_RESEED_TIME_INTERVAL)
843         return 0;
844
845     master_reseed_interval = _master_reseed_interval;
846     slave_reseed_interval = _slave_reseed_interval;
847
848     master_reseed_time_interval = _master_reseed_time_interval;
849     slave_reseed_time_interval = _slave_reseed_time_interval;
850
851     return 1;
852 }
853
854 /*
855  * Locks the given drbg. Locking a drbg which does not have locking
856  * enabled is considered a successful no-op.
857  *
858  * Returns 1 on success, 0 on failure.
859  */
860 int rand_drbg_lock(RAND_DRBG *drbg)
861 {
862     if (drbg->lock != NULL)
863         return CRYPTO_THREAD_write_lock(drbg->lock);
864
865     return 1;
866 }
867
868 /*
869  * Unlocks the given drbg. Unlocking a drbg which does not have locking
870  * enabled is considered a successful no-op.
871  *
872  * Returns 1 on success, 0 on failure.
873  */
874 int rand_drbg_unlock(RAND_DRBG *drbg)
875 {
876     if (drbg->lock != NULL)
877         return CRYPTO_THREAD_unlock(drbg->lock);
878
879     return 1;
880 }
881
882 /*
883  * Enables locking for the given drbg
884  *
885  * Locking can only be enabled if the random generator
886  * is in the uninitialized state.
887  *
888  * Returns 1 on success, 0 on failure.
889  */
890 int rand_drbg_enable_locking(RAND_DRBG *drbg)
891 {
892     if (drbg->state != DRBG_UNINITIALISED) {
893         RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING,
894                 RAND_R_DRBG_ALREADY_INITIALIZED);
895         return 0;
896     }
897
898     if (drbg->lock == NULL) {
899         if (drbg->parent != NULL && drbg->parent->lock == NULL) {
900             RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING,
901                     RAND_R_PARENT_LOCKING_NOT_ENABLED);
902             return 0;
903         }
904
905         drbg->lock = CRYPTO_THREAD_lock_new();
906         if (drbg->lock == NULL) {
907             RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING,
908                     RAND_R_FAILED_TO_CREATE_LOCK);
909             return 0;
910         }
911     }
912
913     return 1;
914 }
915
916 /*
917  * Get and set the EXDATA
918  */
919 int RAND_DRBG_set_ex_data(RAND_DRBG *drbg, int idx, void *arg)
920 {
921     return CRYPTO_set_ex_data(&drbg->ex_data, idx, arg);
922 }
923
924 void *RAND_DRBG_get_ex_data(const RAND_DRBG *drbg, int idx)
925 {
926     return CRYPTO_get_ex_data(&drbg->ex_data, idx);
927 }
928
929
930 /*
931  * The following functions provide a RAND_METHOD that works on the
932  * global DRBG.  They lock.
933  */
934
935 /*
936  * Allocates a new global DRBG on the secure heap (if enabled) and
937  * initializes it with default settings.
938  *
939  * Returns a pointer to the new DRBG instance on success, NULL on failure.
940  */
941 static RAND_DRBG *drbg_setup(RAND_DRBG *parent, int drbg_type)
942 {
943     RAND_DRBG *drbg;
944
945     drbg = RAND_DRBG_secure_new(rand_drbg_type[drbg_type],
946                                 rand_drbg_flags[drbg_type], parent);
947     if (drbg == NULL)
948         return NULL;
949
950     /* Only the master DRBG needs to have a lock */
951     if (parent == NULL && rand_drbg_enable_locking(drbg) == 0)
952         goto err;
953
954     /* enable seed propagation */
955     tsan_store(&drbg->reseed_prop_counter, 1);
956
957     /*
958      * Ignore instantiation error to support just-in-time instantiation.
959      *
960      * The state of the drbg will be checked in RAND_DRBG_generate() and
961      * an automatic recovery is attempted.
962      */
963     (void)RAND_DRBG_instantiate(drbg,
964                                 (const unsigned char *) ossl_pers_string,
965                                 sizeof(ossl_pers_string) - 1);
966     return drbg;
967
968 err:
969     RAND_DRBG_free(drbg);
970     return NULL;
971 }
972
973 /*
974  * Initialize the global DRBGs on first use.
975  * Returns 1 on success, 0 on failure.
976  */
977 DEFINE_RUN_ONCE_STATIC(do_rand_drbg_init)
978 {
979     /*
980      * ensure that libcrypto is initialized, otherwise the
981      * DRBG locks are not cleaned up properly
982      */
983     if (!OPENSSL_init_crypto(0, NULL))
984         return 0;
985
986     if (!CRYPTO_THREAD_init_local(&private_drbg, NULL))
987         return 0;
988
989     if (!CRYPTO_THREAD_init_local(&public_drbg, NULL))
990         goto err1;
991
992     master_drbg = drbg_setup(NULL, RAND_DRBG_TYPE_MASTER);
993     if (master_drbg == NULL)
994         goto err2;
995
996     return 1;
997
998 err2:
999     CRYPTO_THREAD_cleanup_local(&public_drbg);
1000 err1:
1001     CRYPTO_THREAD_cleanup_local(&private_drbg);
1002     return 0;
1003 }
1004
1005 /* Clean up the global DRBGs before exit */
1006 void rand_drbg_cleanup_int(void)
1007 {
1008     if (master_drbg != NULL) {
1009         RAND_DRBG_free(master_drbg);
1010         master_drbg = NULL;
1011
1012         CRYPTO_THREAD_cleanup_local(&private_drbg);
1013         CRYPTO_THREAD_cleanup_local(&public_drbg);
1014     }
1015 }
1016
1017 void drbg_delete_thread_state(void)
1018 {
1019     RAND_DRBG *drbg;
1020
1021     drbg = CRYPTO_THREAD_get_local(&public_drbg);
1022     CRYPTO_THREAD_set_local(&public_drbg, NULL);
1023     RAND_DRBG_free(drbg);
1024
1025     drbg = CRYPTO_THREAD_get_local(&private_drbg);
1026     CRYPTO_THREAD_set_local(&private_drbg, NULL);
1027     RAND_DRBG_free(drbg);
1028 }
1029
1030 /* Implements the default OpenSSL RAND_bytes() method */
1031 static int drbg_bytes(unsigned char *out, int count)
1032 {
1033     int ret;
1034     RAND_DRBG *drbg = RAND_DRBG_get0_public();
1035
1036     if (drbg == NULL)
1037         return 0;
1038
1039     ret = RAND_DRBG_bytes(drbg, out, count);
1040
1041     return ret;
1042 }
1043
1044 /*
1045  * Calculates the minimum length of a full entropy buffer
1046  * which is necessary to seed (i.e. instantiate) the DRBG
1047  * successfully.
1048  *
1049  * NOTE: There is a copy of this function in drbgtest.c.
1050  *       If you change anything here, you need to update
1051  *       the copy accordingly.
1052  */
1053 static size_t rand_drbg_seedlen(RAND_DRBG *drbg)
1054 {
1055     /*
1056      * If no os entropy source is available then RAND_seed(buffer, bufsize)
1057      * is expected to succeed if and only if the buffer length satisfies
1058      * the following requirements, which follow from the calculations
1059      * in RAND_DRBG_instantiate().
1060      */
1061     size_t min_entropy = drbg->strength;
1062     size_t min_entropylen = drbg->min_entropylen;
1063
1064     /*
1065      * Extra entropy for the random nonce in the absence of a
1066      * get_nonce callback, see comment in RAND_DRBG_instantiate().
1067      */
1068     if (drbg->min_noncelen > 0 && drbg->get_nonce == NULL) {
1069         min_entropy += drbg->strength / 2;
1070         min_entropylen += drbg->min_noncelen;
1071     }
1072
1073     /*
1074      * Convert entropy requirement from bits to bytes
1075      * (dividing by 8 without rounding upwards, because
1076      * all entropy requirements are divisible by 8).
1077      */
1078     min_entropy >>= 3;
1079
1080     /* Return a value that satisfies both requirements */
1081     return min_entropy > min_entropylen ? min_entropy : min_entropylen;
1082 }
1083
1084 /* Implements the default OpenSSL RAND_add() method */
1085 static int drbg_add(const void *buf, int num, double randomness)
1086 {
1087     int ret = 0;
1088     RAND_DRBG *drbg = RAND_DRBG_get0_master();
1089     size_t buflen;
1090     size_t seedlen;
1091
1092     if (drbg == NULL)
1093         return 0;
1094
1095     if (num < 0 || randomness < 0.0)
1096         return 0;
1097
1098     rand_drbg_lock(drbg);
1099     seedlen = rand_drbg_seedlen(drbg);
1100
1101     buflen = (size_t)num;
1102
1103     if (buflen < seedlen || randomness < (double) seedlen) {
1104 #if defined(OPENSSL_RAND_SEED_NONE)
1105         /*
1106          * If no os entropy source is available, a reseeding will fail
1107          * inevitably. So we use a trick to mix the buffer contents into
1108          * the DRBG state without forcing a reseeding: we generate a
1109          * dummy random byte, using the buffer content as additional data.
1110          * Note: This won't work with RAND_DRBG_FLAG_CTR_NO_DF.
1111          */
1112         unsigned char dummy[1];
1113
1114         ret = RAND_DRBG_generate(drbg, dummy, sizeof(dummy), 0, buf, buflen);
1115         rand_drbg_unlock(drbg);
1116         return ret;
1117 #else
1118         /*
1119          * If an os entropy source is avaible then we declare the buffer content
1120          * as additional data by setting randomness to zero and trigger a regular
1121          * reseeding.
1122          */
1123         randomness = 0.0;
1124 #endif
1125     }
1126
1127
1128     if (randomness > (double)seedlen) {
1129         /*
1130          * The purpose of this check is to bound |randomness| by a
1131          * relatively small value in order to prevent an integer
1132          * overflow when multiplying by 8 in the rand_drbg_restart()
1133          * call below. Note that randomness is measured in bytes,
1134          * not bits, so this value corresponds to eight times the
1135          * security strength.
1136          */
1137         randomness = (double)seedlen;
1138     }
1139
1140     ret = rand_drbg_restart(drbg, buf, buflen, (size_t)(8 * randomness));
1141     rand_drbg_unlock(drbg);
1142
1143     return ret;
1144 }
1145
1146 /* Implements the default OpenSSL RAND_seed() method */
1147 static int drbg_seed(const void *buf, int num)
1148 {
1149     return drbg_add(buf, num, num);
1150 }
1151
1152 /* Implements the default OpenSSL RAND_status() method */
1153 static int drbg_status(void)
1154 {
1155     int ret;
1156     RAND_DRBG *drbg = RAND_DRBG_get0_master();
1157
1158     if (drbg == NULL)
1159         return 0;
1160
1161     rand_drbg_lock(drbg);
1162     ret = drbg->state == DRBG_READY ? 1 : 0;
1163     rand_drbg_unlock(drbg);
1164     return ret;
1165 }
1166
1167 /*
1168  * Get the master DRBG.
1169  * Returns pointer to the DRBG on success, NULL on failure.
1170  *
1171  */
1172 RAND_DRBG *RAND_DRBG_get0_master(void)
1173 {
1174     if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
1175         return NULL;
1176
1177     return master_drbg;
1178 }
1179
1180 /*
1181  * Get the public DRBG.
1182  * Returns pointer to the DRBG on success, NULL on failure.
1183  */
1184 RAND_DRBG *RAND_DRBG_get0_public(void)
1185 {
1186     RAND_DRBG *drbg;
1187
1188     if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
1189         return NULL;
1190
1191     drbg = CRYPTO_THREAD_get_local(&public_drbg);
1192     if (drbg == NULL) {
1193         if (!ossl_init_thread_start(OPENSSL_INIT_THREAD_RAND))
1194             return NULL;
1195         drbg = drbg_setup(master_drbg, RAND_DRBG_TYPE_PUBLIC);
1196         CRYPTO_THREAD_set_local(&public_drbg, drbg);
1197     }
1198     return drbg;
1199 }
1200
1201 /*
1202  * Get the private DRBG.
1203  * Returns pointer to the DRBG on success, NULL on failure.
1204  */
1205 RAND_DRBG *RAND_DRBG_get0_private(void)
1206 {
1207     RAND_DRBG *drbg;
1208
1209     if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
1210         return NULL;
1211
1212     drbg = CRYPTO_THREAD_get_local(&private_drbg);
1213     if (drbg == NULL) {
1214         if (!ossl_init_thread_start(OPENSSL_INIT_THREAD_RAND))
1215             return NULL;
1216         drbg = drbg_setup(master_drbg, RAND_DRBG_TYPE_PRIVATE);
1217         CRYPTO_THREAD_set_local(&private_drbg, drbg);
1218     }
1219     return drbg;
1220 }
1221
1222 RAND_METHOD rand_meth = {
1223     drbg_seed,
1224     drbg_bytes,
1225     NULL,
1226     drbg_add,
1227     drbg_bytes,
1228     drbg_status
1229 };
1230
1231 RAND_METHOD *RAND_OpenSSL(void)
1232 {
1233     return &rand_meth;
1234 }