crypto/rand/rand_local.h

   1 /*
   2  * Copyright 1995-2020 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 OSSL_CRYPTO_RAND_LOCAL_H
  11 # define OSSL_CRYPTO_RAND_LOCAL_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 chosen 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_ecb;
 179     EVP_CIPHER_CTX *ctx_ctr;
 180     EVP_CIPHER_CTX *ctx_df;
 181     EVP_CIPHER *cipher_ecb;
 182     EVP_CIPHER *cipher_ctr;
 183     size_t keylen;
 184     unsigned char K[32];
 185     unsigned char V[16];
 186     /* Temporary block storage used by ctr_df */
 187     unsigned char bltmp[16];
 188     size_t bltmp_pos;
 189     unsigned char KX[48];
 190 } RAND_DRBG_CTR;
 191
 192
 193 /*
 194  * The 'random pool' acts as a dumb container for collecting random
 195  * input from various entropy sources. The pool has no knowledge about
 196  * whether its randomness is fed into a legacy RAND_METHOD via RAND_add()
 197  * or into a new style RAND_DRBG. It is the callers duty to 1) initialize the
 198  * random pool, 2) pass it to the polling callbacks, 3) seed the RNG, and
 199  * 4) cleanup the random pool again.
 200  *
 201  * The random pool contains no locking mechanism because its scope and
 202  * lifetime is intended to be restricted to a single stack frame.
 203  */
 204 struct rand_pool_st {
 205     unsigned char *buffer;  /* points to the beginning of the random pool */
 206     size_t len; /* current number of random bytes contained in the pool */
 207
 208     int attached;  /* true pool was attached to existing buffer */
 209     int secure;    /* 1: allocated on the secure heap, 0: otherwise */
 210
 211     size_t min_len; /* minimum number of random bytes requested */
 212     size_t max_len; /* maximum number of random bytes (allocated buffer size) */
 213     size_t alloc_len; /* current number of bytes allocated */
 214     size_t entropy; /* current entropy count in bits */
 215     size_t entropy_requested; /* requested entropy count in bits */
 216 };
 217
 218 /*
 219  * The state of all types of DRBGs, even though we only have CTR mode
 220  * right now.
 221  */
 222 struct rand_drbg_st {
 223     CRYPTO_RWLOCK *lock;
 224     /* The library context this DRBG is associated with, if any */
 225     OPENSSL_CTX *libctx;
 226     RAND_DRBG *parent;
 227     int secure; /* 1: allocated on the secure heap, 0: otherwise */
 228     int type; /* the nid of the underlying algorithm */
 229     /*
 230      * Stores the return value of openssl_get_fork_id() as of when we last
 231      * reseeded.  The DRBG reseeds automatically whenever drbg->fork_id !=
 232      * openssl_get_fork_id().  Used to provide fork-safety and reseed this
 233      * DRBG in the child process.
 234      */
 235     int fork_id;
 236     unsigned short flags; /* various external flags */
 237
 238     /*
 239      * The random_data is used by RAND_add()/drbg_add() to attach random
 240      * data to the global drbg, such that the rand_drbg_get_entropy() callback
 241      * can pull it during instantiation and reseeding. This is necessary to
 242      * reconcile the different philosophies of the RAND and the RAND_DRBG
 243      * with respect to how randomness is added to the RNG during reseeding
 244      * (see PR #4328).
 245      */
 246     struct rand_pool_st *seed_pool;
 247
 248     /*
 249      * Auxiliary pool for additional data.
 250      */
 251     struct rand_pool_st *adin_pool;
 252
 253     /*
 254      * The following parameters are setup by the per-type "init" function.
 255      *
 256      * The supported types and their init functions are:
 257      *    (1) CTR_DRBG:  drbg_ctr_init().
 258      *    (2) HMAC_DRBG: drbg_hmac_init().
 259      *    (3) HASH_DRBG: drbg_hash_init().
 260      *
 261      * The parameters are closely related to the ones described in
 262      * section '10.2.1 CTR_DRBG' of [NIST SP 800-90Ar1], with one
 263      * crucial difference: In the NIST standard, all counts are given
 264      * in bits, whereas in OpenSSL entropy counts are given in bits
 265      * and buffer lengths are given in bytes.
 266      *
 267      * Since this difference has lead to some confusion in the past,
 268      * (see [GitHub Issue #2443], formerly [rt.openssl.org #4055])
 269      * the 'len' suffix has been added to all buffer sizes for
 270      * clarification.
 271      */
 272
 273     int strength;
 274     size_t max_request;
 275     size_t min_entropylen, max_entropylen;
 276     size_t min_noncelen, max_noncelen;
 277     size_t max_perslen, max_adinlen;
 278
 279     /*
 280      * Counts the number of generate requests since the last reseed
 281      * (Starts at 1). This value is the reseed_counter as defined in
 282      * NIST SP 800-90Ar1
 283      */
 284     unsigned int reseed_gen_counter;
 285     /*
 286      * Maximum number of generate requests until a reseed is required.
 287      * This value is ignored if it is zero.
 288      */
 289     unsigned int reseed_interval;
 290     /* Stores the time when the last reseeding occurred */
 291     time_t reseed_time;
 292     /*
 293      * Specifies the maximum time interval (in seconds) between reseeds.
 294      * This value is ignored if it is zero.
 295      */
 296     time_t reseed_time_interval;
 297     /*
 298      * Counts the number of reseeds since instantiation.
 299      * This value is ignored if it is zero.
 300      *
 301      * This counter is used only for seed propagation from the <master> DRBG
 302      * to its two children, the <public> and <private> DRBG. This feature is
 303      * very special and its sole purpose is to ensure that any randomness which
 304      * is added by RAND_add() or RAND_seed() will have an immediate effect on
 305      * the output of RAND_bytes() resp. RAND_priv_bytes().
 306      */
 307     TSAN_QUALIFIER unsigned int reseed_prop_counter;
 308     unsigned int reseed_next_counter;
 309
 310     size_t seedlen;
 311     DRBG_STATUS state;
 312
 313 #ifndef FIPS_MODULE
 314     /* Application data, mainly used in the KATs. */
 315     CRYPTO_EX_DATA ex_data;
 316 #endif
 317
 318     /* Implementation specific data */
 319     union {
 320         RAND_DRBG_CTR ctr;
 321         RAND_DRBG_HASH hash;
 322         RAND_DRBG_HMAC hmac;
 323     } data;
 324
 325     /* Implementation specific methods */
 326     RAND_DRBG_METHOD *meth;
 327
 328     /* Callback functions.  See comments in rand_lib.c */
 329     RAND_DRBG_get_entropy_fn get_entropy;
 330     RAND_DRBG_cleanup_entropy_fn cleanup_entropy;
 331     RAND_DRBG_get_nonce_fn get_nonce;
 332     RAND_DRBG_cleanup_nonce_fn cleanup_nonce;
 333
 334     void *callback_data;
 335 };
 336
 337 /* The global RAND method, and the global buffer and DRBG instance. */
 338 extern RAND_METHOD rand_meth;
 339
 340 /* DRBG helpers */
 341 int rand_drbg_restart(RAND_DRBG *drbg,
 342                       const unsigned char *buffer, size_t len, size_t entropy);
 343 size_t rand_drbg_seedlen(RAND_DRBG *drbg);
 344 /* locking api */
 345 int rand_drbg_lock(RAND_DRBG *drbg);
 346 int rand_drbg_unlock(RAND_DRBG *drbg);
 347 int rand_drbg_enable_locking(RAND_DRBG *drbg);
 348
 349
 350 /* initializes the DRBG implementation */
 351 int drbg_ctr_init(RAND_DRBG *drbg);
 352 int drbg_hash_init(RAND_DRBG *drbg);
 353 int drbg_hmac_init(RAND_DRBG *drbg);
 354
 355 /*
 356  * Entropy call back for the FIPS 140-2 section 4.9.2 Conditional Tests.
 357  * These need to be exposed for the unit tests.
 358  */
 359 int rand_crngt_get_entropy_cb(OPENSSL_CTX *ctx, RAND_POOL *pool,
 360                               unsigned char *buf, unsigned char *md,
 361                               unsigned int *md_size);
 362 extern int (*crngt_get_entropy)(OPENSSL_CTX *ctx, RAND_POOL *pool,
 363                                 unsigned char *buf, unsigned char *md,
 364                                 unsigned int *md_size);
 365
 366 #endif