crypto/rand/rand_lcl.h

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