1 /* 2 * Copyright 1995-2018 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 #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 21 # include "internal/numbers.h" 22 23 /* How many times to read the TSC as a randomness source. */ 24 # define TSC_READ_COUNT 4 25 26 /* Maximum reseed intervals */ 27 # define MAX_RESEED_INTERVAL (1 << 24) 28 # define MAX_RESEED_TIME_INTERVAL (1 << 20) /* approx. 12 days */ 29 30 /* Default reseed intervals */ 31 # define MASTER_RESEED_INTERVAL (1 << 8) 32 # define SLAVE_RESEED_INTERVAL (1 << 16) 33 # define MASTER_RESEED_TIME_INTERVAL (60*60) /* 1 hour */ 34 # define SLAVE_RESEED_TIME_INTERVAL (7*60) /* 7 minutes */ 35 36 37 38 /* 39 * Maximum input size for the DRBG (entropy, nonce, personalization string) 40 * 41 * NIST SP800 90Ar1 allows a maximum of (1 << 35) bits i.e., (1 << 32) bytes. 42 * 43 * We lower it to 'only' INT32_MAX bytes, which is equivalent to 2 gigabytes. 44 */ 45 # define DRBG_MAX_LENGTH INT32_MAX 46 47 48 49 /* 50 * Maximum allocation size for RANDOM_POOL buffers 51 * 52 * The max_len value for the buffer provided to the rand_drbg_get_entropy() 53 * callback is currently 2^31 bytes (2 gigabytes), if a derivation function 54 * is used. Since this is much too large to be allocated, the rand_pool_new() 55 * function chooses more modest values as default pool length, bounded 56 * by RAND_POOL_MIN_LENGTH and RAND_POOL_MAX_LENGTH 57 * 58 * The choice of the RAND_POOL_FACTOR is large enough such that the 59 * RAND_POOL can store a random input which has a lousy entropy rate of 60 * 8/256 (= 0.03125) bits per byte. This input will be sent through the 61 * derivation function which 'compresses' the low quality input into a 62 * high quality output. 63 * 64 * The factor 1.5 below is the pessimistic estimate for the extra amount 65 * of entropy required when no get_nonce() callback is defined. 66 */ 67 # define RAND_POOL_FACTOR 256 68 # define RAND_POOL_MAX_LENGTH (RAND_POOL_FACTOR * \ 69 3 * (RAND_DRBG_STRENGTH / 16)) 70 /* 71 * = (RAND_POOL_FACTOR * \ 72 * 1.5 * (RAND_DRBG_STRENGTH / 8)) 73 */ 74 75 76 /* DRBG status values */ 77 typedef enum drbg_status_e { 78 DRBG_UNINITIALISED, 79 DRBG_READY, 80 DRBG_ERROR 81 } DRBG_STATUS; 82 83 84 /* instantiate */ 85 typedef int (*RAND_DRBG_instantiate_fn)(RAND_DRBG *ctx, 86 const unsigned char *ent, 87 size_t entlen, 88 const unsigned char *nonce, 89 size_t noncelen, 90 const unsigned char *pers, 91 size_t perslen); 92 /* reseed */ 93 typedef int (*RAND_DRBG_reseed_fn)(RAND_DRBG *ctx, 94 const unsigned char *ent, 95 size_t entlen, 96 const unsigned char *adin, 97 size_t adinlen); 98 /* generate output */ 99 typedef int (*RAND_DRBG_generate_fn)(RAND_DRBG *ctx, 100 unsigned char *out, 101 size_t outlen, 102 const unsigned char *adin, 103 size_t adinlen); 104 /* uninstantiate */ 105 typedef int (*RAND_DRBG_uninstantiate_fn)(RAND_DRBG *ctx); 106 107 108 /* 109 * The DRBG methods 110 */ 111 112 typedef struct rand_drbg_method_st { 113 RAND_DRBG_instantiate_fn instantiate; 114 RAND_DRBG_reseed_fn reseed; 115 RAND_DRBG_generate_fn generate; 116 RAND_DRBG_uninstantiate_fn uninstantiate; 117 } RAND_DRBG_METHOD; 118 119 120 /* 121 * The state of a DRBG AES-CTR. 122 */ 123 typedef struct rand_drbg_ctr_st { 124 EVP_CIPHER_CTX *ctx; 125 EVP_CIPHER_CTX *ctx_df; 126 const EVP_CIPHER *cipher; 127 size_t keylen; 128 unsigned char K[32]; 129 unsigned char V[16]; 130 /* Temporary block storage used by ctr_df */ 131 unsigned char bltmp[16]; 132 size_t bltmp_pos; 133 unsigned char KX[48]; 134 } RAND_DRBG_CTR; 135 136 137 /* 138 * The 'random pool' acts as a dumb container for collecting random 139 * input from various entropy sources. The pool has no knowledge about 140 * whether its randomness is fed into a legacy RAND_METHOD via RAND_add() 141 * or into a new style RAND_DRBG. It is the callers duty to 1) initialize the 142 * random pool, 2) pass it to the polling callbacks, 3) seed the RNG, and 143 * 4) cleanup the random pool again. 144 * 145 * The random pool contains no locking mechanism because its scope and 146 * lifetime is intended to be restricted to a single stack frame. 147 */ 148 struct rand_pool_st { 149 unsigned char *buffer; /* points to the beginning of the random pool */ 150 size_t len; /* current number of random bytes contained in the pool */ 151 152 int attached; /* true pool was attached to existing buffer */ 153 154 size_t min_len; /* minimum number of random bytes requested */ 155 size_t max_len; /* maximum number of random bytes (allocated buffer size) */ 156 size_t entropy; /* current entropy count in bits */ 157 size_t entropy_requested; /* requested entropy count in bits */ 158 }; 159 160 /* 161 * The state of all types of DRBGs, even though we only have CTR mode 162 * right now. 163 */ 164 struct rand_drbg_st { 165 CRYPTO_RWLOCK *lock; 166 RAND_DRBG *parent; 167 int secure; /* 1: allocated on the secure heap, 0: otherwise */ 168 int type; /* the nid of the underlying algorithm */ 169 /* 170 * Stores the value of the rand_fork_count global as of when we last 171 * reseeded. The DRBG reseeds automatically whenever drbg->fork_count != 172 * rand_fork_count. Used to provide fork-safety and reseed this DRBG in 173 * the child process. 174 */ 175 int fork_count; 176 unsigned short flags; /* various external flags */ 177 178 /* 179 * The random_data is used by RAND_add()/drbg_add() to attach random 180 * data to the global drbg, such that the rand_drbg_get_entropy() callback 181 * can pull it during instantiation and reseeding. This is necessary to 182 * reconcile the different philosophies of the RAND and the RAND_DRBG 183 * with respect to how randomness is added to the RNG during reseeding 184 * (see PR #4328). 185 */ 186 struct rand_pool_st *seed_pool; 187 188 /* 189 * Auxiliary pool for additional data. 190 */ 191 struct rand_pool_st *adin_pool; 192 193 /* 194 * The following parameters are setup by the per-type "init" function. 195 * 196 * Currently the only type is CTR_DRBG, its init function is drbg_ctr_init(). 197 * 198 * The parameters are closely related to the ones described in 199 * section '10.2.1 CTR_DRBG' of [NIST SP 800-90Ar1], with one 200 * crucial difference: In the NIST standard, all counts are given 201 * in bits, whereas in OpenSSL entropy counts are given in bits 202 * and buffer lengths are given in bytes. 203 * 204 * Since this difference has lead to some confusion in the past, 205 * (see [GitHub Issue #2443], formerly [rt.openssl.org #4055]) 206 * the 'len' suffix has been added to all buffer sizes for 207 * clarification. 208 */ 209 210 int strength; 211 size_t max_request; 212 size_t min_entropylen, max_entropylen; 213 size_t min_noncelen, max_noncelen; 214 size_t max_perslen, max_adinlen; 215 216 /* Counts the number of generate requests since the last reseed. */ 217 unsigned int reseed_gen_counter; 218 /* 219 * Maximum number of generate requests until a reseed is required. 220 * This value is ignored if it is zero. 221 */ 222 unsigned int reseed_interval; 223 /* Stores the time when the last reseeding occurred */ 224 time_t reseed_time; 225 /* 226 * Specifies the maximum time interval (in seconds) between reseeds. 227 * This value is ignored if it is zero. 228 */ 229 time_t reseed_time_interval; 230 /* 231 * Counts the number of reseeds since instantiation. 232 * This value is ignored if it is zero. 233 * 234 * This counter is used only for seed propagation from the <master> DRBG 235 * to its two children, the <public> and <private> DRBG. This feature is 236 * very special and its sole purpose is to ensure that any randomness which 237 * is added by RAND_add() or RAND_seed() will have an immediate effect on 238 * the output of RAND_bytes() resp. RAND_priv_bytes(). 239 */ 240 TSAN_QUALIFIER unsigned int reseed_prop_counter; 241 unsigned int reseed_next_counter; 242 243 size_t seedlen; 244 DRBG_STATUS state; 245 246 /* Application data, mainly used in the KATs. */ 247 CRYPTO_EX_DATA ex_data; 248 249 /* Implementation specific data (currently only one implementation) */ 250 union { 251 RAND_DRBG_CTR ctr; 252 } data; 253 254 /* Implementation specific methods */ 255 RAND_DRBG_METHOD *meth; 256 257 /* Callback functions. See comments in rand_lib.c */ 258 RAND_DRBG_get_entropy_fn get_entropy; 259 RAND_DRBG_cleanup_entropy_fn cleanup_entropy; 260 RAND_DRBG_get_nonce_fn get_nonce; 261 RAND_DRBG_cleanup_nonce_fn cleanup_nonce; 262 }; 263 264 /* The global RAND method, and the global buffer and DRBG instance. */ 265 extern RAND_METHOD rand_meth; 266 267 /* 268 * A "generation count" of forks. Incremented in the child process after a 269 * fork. Since rand_fork_count is increment-only, and only ever written to in 270 * the child process of the fork, which is guaranteed to be single-threaded, no 271 * locking is needed for normal (read) accesses; the rest of pthread fork 272 * processing is assumed to introduce the necessary memory barriers. Sibling 273 * children of a given parent will produce duplicate values, but this is not 274 * problematic because the reseeding process pulls input from the system CSPRNG 275 * and/or other global sources, so the siblings will end up generating 276 * different output streams. 277 */ 278 extern int rand_fork_count; 279 280 /* DRBG helpers */ 281 int rand_drbg_restart(RAND_DRBG *drbg, 282 const unsigned char *buffer, size_t len, size_t entropy); 283 size_t rand_drbg_seedlen(RAND_DRBG *drbg); 284 /* locking api */ 285 int rand_drbg_lock(RAND_DRBG *drbg); 286 int rand_drbg_unlock(RAND_DRBG *drbg); 287 int rand_drbg_enable_locking(RAND_DRBG *drbg); 288 289 290 /* initializes the AES-CTR DRBG implementation */ 291 int drbg_ctr_init(RAND_DRBG *drbg); 292 293 #endif 294