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1 /*
2 * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
3 *
4 * Licensed under the Apache License 2.0 (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 #ifndef HEADER_RAND_LCL_H
11 # define HEADER_RAND_LCL_H
12
13 # include <openssl/aes.h>
14 # include <openssl/evp.h>
15 # include <openssl/sha.h>
16 # include <openssl/hmac.h>
17 # include <openssl/ec.h>
18 # include <openssl/rand_drbg.h>
19 # include "internal/tsan_assist.h"
20 # include "crypto/rand.h"
21
22 # include "internal/numbers.h"
23
24 /* How many times to read the TSC as a randomness source. */
25 # define TSC_READ_COUNT 4
26
27 /* Maximum reseed intervals */
28 # define MAX_RESEED_INTERVAL (1 << 24)
29 # define MAX_RESEED_TIME_INTERVAL (1 << 20) /* approx. 12 days */
30
31 /* Default reseed intervals */
32 # define MASTER_RESEED_INTERVAL (1 << 8)
33 # define SLAVE_RESEED_INTERVAL (1 << 16)
34 # define MASTER_RESEED_TIME_INTERVAL (60*60) /* 1 hour */
35 # define SLAVE_RESEED_TIME_INTERVAL (7*60) /* 7 minutes */
36
37 /*
38 * The number of bytes that constitutes an atomic lump of entropy with respect
39 * to the FIPS 140-2 section 4.9.2 Conditional Tests. The size is somewhat
40 * arbitrary, the smaller the value, the less entropy is consumed on first
41 * read but the higher the probability of the test failing by accident.
42 *
43 * The value is in bytes.
44 */
45 #define CRNGT_BUFSIZ 16
46
47 /*
48 * Maximum input size for the DRBG (entropy, nonce, personalization string)
49 *
50 * NIST SP800 90Ar1 allows a maximum of (1 << 35) bits i.e., (1 << 32) bytes.
51 *
52 * We lower it to 'only' INT32_MAX bytes, which is equivalent to 2 gigabytes.
53 */
54 # define DRBG_MAX_LENGTH INT32_MAX
55
56 /* The default nonce */
57 #ifdef CHARSET_EBCDIC
58 # define DRBG_DEFAULT_PERS_STRING { 0x4f, 0x70, 0x65, 0x6e, 0x53, 0x53, \
59 0x4c, 0x20, 0x4e, 0x49, 0x53, 0x54, 0x20, 0x53, 0x50, 0x20, 0x38, 0x30, \
60 0x30, 0x2d, 0x39, 0x30, 0x41, 0x20, 0x44, 0x52, 0x42, 0x47, 0x00};
61 #else
62 # define DRBG_DEFAULT_PERS_STRING "OpenSSL NIST SP 800-90A DRBG"
63 #endif
64
65 /*
66 * Maximum allocation size for RANDOM_POOL buffers
67 *
68 * The max_len value for the buffer provided to the rand_drbg_get_entropy()
69 * callback is currently 2^31 bytes (2 gigabytes), if a derivation function
70 * is used. Since this is much too large to be allocated, the rand_pool_new()
71 * function chooses more modest values as default pool length, bounded
72 * by RAND_POOL_MIN_LENGTH and RAND_POOL_MAX_LENGTH
73 *
74 * The choice of the RAND_POOL_FACTOR is large enough such that the
75 * RAND_POOL can store a random input which has a lousy entropy rate of
76 * 8/256 (= 0.03125) bits per byte. This input will be sent through the
77 * derivation function which 'compresses' the low quality input into a
78 * high quality output.
79 *
80 * The factor 1.5 below is the pessimistic estimate for the extra amount
81 * of entropy required when no get_nonce() callback is defined.
82 */
83 # define RAND_POOL_FACTOR 256
84 # define RAND_POOL_MAX_LENGTH (RAND_POOL_FACTOR * \
85 3 * (RAND_DRBG_STRENGTH / 16))
86 /*
87 * = (RAND_POOL_FACTOR * \
88 * 1.5 * (RAND_DRBG_STRENGTH / 8))
89 */
90
91 /*
92 * Initial allocation minimum.
93 *
94 * There is a distinction between the secure and normal allocation minimums.
95 * Ideally, the secure allocation size should be a power of two. The normal
96 * allocation size doesn't have any such restriction.
97 *
98 * The secure value is based on 128 bits of secure material, which is 16 bytes.
99 * Typically, the DRBGs will set a minimum larger than this so optimal
100 * allocation ought to take place (for full quality seed material).
101 *
102 * The normal value has been chosed by noticing that the rand_drbg_get_nonce
103 * function is usually the largest of the built in allocation (twenty four
104 * bytes and then appending another sixteen bytes). This means the buffer ends
105 * with 40 bytes. The value of forty eight is comfortably above this which
106 * allows some slack in the platform specific values used.
107 */
108 # define RAND_POOL_MIN_ALLOCATION(secure) ((secure) ? 16 : 48)
109
110 /* DRBG status values */
111 typedef enum drbg_status_e {
112 DRBG_UNINITIALISED,
113 DRBG_READY,
114 DRBG_ERROR
115 } DRBG_STATUS;
116
117
118 /* instantiate */
119 typedef int (*RAND_DRBG_instantiate_fn)(RAND_DRBG *ctx,
120 const unsigned char *ent,
121 size_t entlen,
122 const unsigned char *nonce,
123 size_t noncelen,
124 const unsigned char *pers,
125 size_t perslen);
126 /* reseed */
127 typedef int (*RAND_DRBG_reseed_fn)(RAND_DRBG *ctx,
128 const unsigned char *ent,
129 size_t entlen,
130 const unsigned char *adin,
131 size_t adinlen);
132 /* generate output */
133 typedef int (*RAND_DRBG_generate_fn)(RAND_DRBG *ctx,
134 unsigned char *out,
135 size_t outlen,
136 const unsigned char *adin,
137 size_t adinlen);
138 /* uninstantiate */
139 typedef int (*RAND_DRBG_uninstantiate_fn)(RAND_DRBG *ctx);
140
141
142 /*
143 * The DRBG methods
144 */
145
146 typedef struct rand_drbg_method_st {
147 RAND_DRBG_instantiate_fn instantiate;
148 RAND_DRBG_reseed_fn reseed;
149 RAND_DRBG_generate_fn generate;
150 RAND_DRBG_uninstantiate_fn uninstantiate;
151 } RAND_DRBG_METHOD;
152
153 /* 888 bits from SP800-90Ar1 10.1 table 2 */
154 #define HASH_PRNG_MAX_SEEDLEN (888/8)
155
156 typedef struct rand_drbg_hash_st {
157 EVP_MD *md;
158 EVP_MD_CTX *ctx;
159 size_t blocklen;
160 unsigned char V[HASH_PRNG_MAX_SEEDLEN];
161 unsigned char C[HASH_PRNG_MAX_SEEDLEN];
162 /* Temporary value storage: should always exceed max digest length */
163 unsigned char vtmp[HASH_PRNG_MAX_SEEDLEN];
164 } RAND_DRBG_HASH;
165
166 typedef struct rand_drbg_hmac_st {
167 EVP_MD *md;
168 HMAC_CTX *ctx;
169 size_t blocklen;
170 unsigned char K[EVP_MAX_MD_SIZE];
171 unsigned char V[EVP_MAX_MD_SIZE];
172 } RAND_DRBG_HMAC;
173
174 /*
175 * The state of a DRBG AES-CTR.
176 */
177 typedef struct rand_drbg_ctr_st {
178 EVP_CIPHER_CTX *ctx;
179 EVP_CIPHER_CTX *ctx_df;
180 EVP_CIPHER *cipher;
181 size_t keylen;
182 unsigned char K[32];
183 unsigned char V[16];
184 /* Temporary block storage used by ctr_df */
185 unsigned char bltmp[16];
186 size_t bltmp_pos;
187 unsigned char KX[48];
188 } RAND_DRBG_CTR;
189
190
191 /*
192 * The 'random pool' acts as a dumb container for collecting random
193 * input from various entropy sources. The pool has no knowledge about
194 * whether its randomness is fed into a legacy RAND_METHOD via RAND_add()
195 * or into a new style RAND_DRBG. It is the callers duty to 1) initialize the
196 * random pool, 2) pass it to the polling callbacks, 3) seed the RNG, and
197 * 4) cleanup the random pool again.
198 *
199 * The random pool contains no locking mechanism because its scope and
200 * lifetime is intended to be restricted to a single stack frame.
201 */
202 struct rand_pool_st {
203 unsigned char *buffer; /* points to the beginning of the random pool */
204 size_t len; /* current number of random bytes contained in the pool */
205
206 int attached; /* true pool was attached to existing buffer */
207 int secure; /* 1: allocated on the secure heap, 0: otherwise */
208
209 size_t min_len; /* minimum number of random bytes requested */
210 size_t max_len; /* maximum number of random bytes (allocated buffer size) */
211 size_t alloc_len; /* current number of bytes allocated */
212 size_t entropy; /* current entropy count in bits */
213 size_t entropy_requested; /* requested entropy count in bits */
214 };
215
216 /*
217 * The state of all types of DRBGs, even though we only have CTR mode
218 * right now.
219 */
220 struct rand_drbg_st {
221 CRYPTO_RWLOCK *lock;
222 /* The library context this DRBG is associated with, if any */
223 OPENSSL_CTX *libctx;
224 RAND_DRBG *parent;
225 int secure; /* 1: allocated on the secure heap, 0: otherwise */
226 int type; /* the nid of the underlying algorithm */
227 /*
228 * Stores the return value of openssl_get_fork_id() as of when we last
229 * reseeded. The DRBG reseeds automatically whenever drbg->fork_id !=
230 * openssl_get_fork_id(). Used to provide fork-safety and reseed this
231 * DRBG in the child process.
232 */
233 int fork_id;
234 unsigned short flags; /* various external flags */
235
236 /*
237 * The random_data is used by RAND_add()/drbg_add() to attach random
238 * data to the global drbg, such that the rand_drbg_get_entropy() callback
239 * can pull it during instantiation and reseeding. This is necessary to
240 * reconcile the different philosophies of the RAND and the RAND_DRBG
241 * with respect to how randomness is added to the RNG during reseeding
242 * (see PR #4328).
243 */
244 struct rand_pool_st *seed_pool;
245
246 /*
247 * Auxiliary pool for additional data.
248 */
249 struct rand_pool_st *adin_pool;
250
251 /*
252 * The following parameters are setup by the per-type "init" function.
253 *
254 * The supported types and their init functions are:
255 * (1) CTR_DRBG: drbg_ctr_init().
256 * (2) HMAC_DRBG: drbg_hmac_init().
257 * (3) HASH_DRBG: drbg_hash_init().
258 *
259 * The parameters are closely related to the ones described in
260 * section '10.2.1 CTR_DRBG' of [NIST SP 800-90Ar1], with one
261 * crucial difference: In the NIST standard, all counts are given
262 * in bits, whereas in OpenSSL entropy counts are given in bits
263 * and buffer lengths are given in bytes.
264 *
265 * Since this difference has lead to some confusion in the past,
266 * (see [GitHub Issue #2443], formerly [rt.openssl.org #4055])
267 * the 'len' suffix has been added to all buffer sizes for
268 * clarification.
269 */
270
271 int strength;
272 size_t max_request;
273 size_t min_entropylen, max_entropylen;
274 size_t min_noncelen, max_noncelen;
275 size_t max_perslen, max_adinlen;
276
277 /*
278 * Counts the number of generate requests since the last reseed
279 * (Starts at 1). This value is the reseed_counter as defined in
280 * NIST SP 800-90Ar1
281 */
282 unsigned int reseed_gen_counter;
283 /*
284 * Maximum number of generate requests until a reseed is required.
285 * This value is ignored if it is zero.
286 */
287 unsigned int reseed_interval;
288 /* Stores the time when the last reseeding occurred */
289 time_t reseed_time;
290 /*
291 * Specifies the maximum time interval (in seconds) between reseeds.
292 * This value is ignored if it is zero.
293 */
294 time_t reseed_time_interval;
295 /*
296 * Counts the number of reseeds since instantiation.
297 * This value is ignored if it is zero.
298 *
299 * This counter is used only for seed propagation from the <master> DRBG
300 * to its two children, the <public> and <private> DRBG. This feature is
301 * very special and its sole purpose is to ensure that any randomness which
302 * is added by RAND_add() or RAND_seed() will have an immediate effect on
303 * the output of RAND_bytes() resp. RAND_priv_bytes().
304 */
305 TSAN_QUALIFIER unsigned int reseed_prop_counter;
306 unsigned int reseed_next_counter;
307
308 size_t seedlen;
309 DRBG_STATUS state;
310
311 /* Application data, mainly used in the KATs. */
312 CRYPTO_EX_DATA ex_data;
313
314 /* Implementation specific data */
315 union {
316 RAND_DRBG_CTR ctr;
317 RAND_DRBG_HASH hash;
318 RAND_DRBG_HMAC hmac;
319 } data;
320
321 /* Implementation specific methods */
322 RAND_DRBG_METHOD *meth;
323
324 /* Callback functions. See comments in rand_lib.c */
325 RAND_DRBG_get_entropy_fn get_entropy;
326 RAND_DRBG_cleanup_entropy_fn cleanup_entropy;
327 RAND_DRBG_get_nonce_fn get_nonce;
328 RAND_DRBG_cleanup_nonce_fn cleanup_nonce;
329 };
330
331 /* The global RAND method, and the global buffer and DRBG instance. */
332 extern RAND_METHOD rand_meth;
333
334 /* DRBG helpers */
335 int rand_drbg_restart(RAND_DRBG *drbg,
336 const unsigned char *buffer, size_t len, size_t entropy);
337 size_t rand_drbg_seedlen(RAND_DRBG *drbg);
338 /* locking api */
339 int rand_drbg_lock(RAND_DRBG *drbg);
340 int rand_drbg_unlock(RAND_DRBG *drbg);
341 int rand_drbg_enable_locking(RAND_DRBG *drbg);
342
343
344 /* initializes the DRBG implementation */
345 int drbg_ctr_init(RAND_DRBG *drbg);
346 int drbg_hash_init(RAND_DRBG *drbg);
347 int drbg_hmac_init(RAND_DRBG *drbg);
348
349 /*
350 * Entropy call back for the FIPS 140-2 section 4.9.2 Conditional Tests.
351 * These need to be exposed for the unit tests.
352 */
353 int rand_crngt_get_entropy_cb(OPENSSL_CTX *ctx, RAND_POOL *pool,
354 unsigned char *buf, unsigned char *md,
355 unsigned int *md_size);
356 extern int (*crngt_get_entropy)(OPENSSL_CTX *ctx, RAND_POOL *pool,
357 unsigned char *buf, unsigned char *md,
358 unsigned int *md_size);
359
360 #endif