/*
* Copyright 1995-2020 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#ifndef OSSL_CRYPTO_RAND_LOCAL_H
# define OSSL_CRYPTO_RAND_LOCAL_H
# include <openssl/aes.h>
# include <openssl/evp.h>
# include <openssl/sha.h>
# include <openssl/hmac.h>
# include <openssl/ec.h>
# include <openssl/rand_drbg.h>
# include "internal/tsan_assist.h"
# include "internal/numbers.h"
/* How many times to read the TSC as a randomness source. */
# define TSC_READ_COUNT 4
/* Maximum reseed intervals */
# define MAX_RESEED_INTERVAL (1 << 24)
# define MAX_RESEED_TIME_INTERVAL (1 << 20) /* approx. 12 days */
/* Default reseed intervals */
# define MASTER_RESEED_INTERVAL (1 << 8)
# define SLAVE_RESEED_INTERVAL (1 << 16)
# define MASTER_RESEED_TIME_INTERVAL (60*60) /* 1 hour */
# define SLAVE_RESEED_TIME_INTERVAL (7*60) /* 7 minutes */
/*
* The number of bytes that constitutes an atomic lump of entropy with respect
* to the FIPS 140-2 section 4.9.2 Conditional Tests. The size is somewhat
* arbitrary, the smaller the value, the less entropy is consumed on first
* read but the higher the probability of the test failing by accident.
*
* The value is in bytes.
*/
#define CRNGT_BUFSIZ 16
/*
* Maximum input size for the DRBG (entropy, nonce, personalization string)
*
* NIST SP800 90Ar1 allows a maximum of (1 << 35) bits i.e., (1 << 32) bytes.
*
* We lower it to 'only' INT32_MAX bytes, which is equivalent to 2 gigabytes.
*/
# define DRBG_MAX_LENGTH INT32_MAX
/* The default nonce */
# define DRBG_DEFAULT_PERS_STRING "OpenSSL NIST SP 800-90A DRBG"
/*
* Maximum allocation size for RANDOM_POOL buffers
*
* The max_len value for the buffer provided to the rand_drbg_get_entropy()
* callback is currently 2^31 bytes (2 gigabytes), if a derivation function
* is used. Since this is much too large to be allocated, the rand_pool_new()
* function chooses more modest values as default pool length, bounded
* by RAND_POOL_MIN_LENGTH and RAND_POOL_MAX_LENGTH
*
* The choice of the RAND_POOL_FACTOR is large enough such that the
* RAND_POOL can store a random input which has a lousy entropy rate of
* 8/256 (= 0.03125) bits per byte. This input will be sent through the
* derivation function which 'compresses' the low quality input into a
* high quality output.
*
* The factor 1.5 below is the pessimistic estimate for the extra amount
* of entropy required when no get_nonce() callback is defined.
*/
# define RAND_POOL_FACTOR 256
# define RAND_POOL_MAX_LENGTH (RAND_POOL_FACTOR * \
3 * (RAND_DRBG_STRENGTH / 16))
/*
* = (RAND_POOL_FACTOR * \
* 1.5 * (RAND_DRBG_STRENGTH / 8))
*/
/*
* Initial allocation minimum.
*
* There is a distinction between the secure and normal allocation minimums.
* Ideally, the secure allocation size should be a power of two. The normal
* allocation size doesn't have any such restriction.
*
* The secure value is based on 128 bits of secure material, which is 16 bytes.
* Typically, the DRBGs will set a minimum larger than this so optimal
* allocation ought to take place (for full quality seed material).
*
* The normal value has been chosen by noticing that the rand_drbg_get_nonce
* function is usually the largest of the built in allocation (twenty four
* bytes and then appending another sixteen bytes). This means the buffer ends
* with 40 bytes. The value of forty eight is comfortably above this which
* allows some slack in the platform specific values used.
*/
# define RAND_POOL_MIN_ALLOCATION(secure) ((secure) ? 16 : 48)
/* DRBG status values */
typedef enum drbg_status_e {
DRBG_UNINITIALISED,
DRBG_READY,
DRBG_ERROR
} DRBG_STATUS;
/* instantiate */
typedef int (*RAND_DRBG_instantiate_fn)(RAND_DRBG *ctx,
const unsigned char *ent,
size_t entlen,
const unsigned char *nonce,
size_t noncelen,
const unsigned char *pers,
size_t perslen);
/* reseed */
typedef int (*RAND_DRBG_reseed_fn)(RAND_DRBG *ctx,
const unsigned char *ent,
size_t entlen,
const unsigned char *adin,
size_t adinlen);
/* generate output */
typedef int (*RAND_DRBG_generate_fn)(RAND_DRBG *ctx,
unsigned char *out,
size_t outlen,
const unsigned char *adin,
size_t adinlen);
/* uninstantiate */
typedef int (*RAND_DRBG_uninstantiate_fn)(RAND_DRBG *ctx);
/*
* The DRBG methods
*/
typedef struct rand_drbg_method_st {
RAND_DRBG_instantiate_fn instantiate;
RAND_DRBG_reseed_fn reseed;
RAND_DRBG_generate_fn generate;
RAND_DRBG_uninstantiate_fn uninstantiate;
} RAND_DRBG_METHOD;
/*
* The state of a DRBG AES-CTR.
*/
typedef struct rand_drbg_ctr_st {
EVP_CIPHER_CTX *ctx;
EVP_CIPHER_CTX *ctx_df;
const EVP_CIPHER *cipher;
size_t keylen;
unsigned char K[32];
unsigned char V[16];
/* Temporary block storage used by ctr_df */
unsigned char bltmp[16];
size_t bltmp_pos;
unsigned char KX[48];
} RAND_DRBG_CTR;
/*
* The 'random pool' acts as a dumb container for collecting random
* input from various entropy sources. The pool has no knowledge about
* whether its randomness is fed into a legacy RAND_METHOD via RAND_add()
* or into a new style RAND_DRBG. It is the callers duty to 1) initialize the
* random pool, 2) pass it to the polling callbacks, 3) seed the RNG, and
* 4) cleanup the random pool again.
*
* The random pool contains no locking mechanism because its scope and
* lifetime is intended to be restricted to a single stack frame.
*/
struct rand_pool_st {
unsigned char *buffer; /* points to the beginning of the random pool */
size_t len; /* current number of random bytes contained in the pool */
int attached; /* true pool was attached to existing buffer */
int secure; /* 1: allocated on the secure heap, 0: otherwise */
size_t min_len; /* minimum number of random bytes requested */
size_t max_len; /* maximum number of random bytes (allocated buffer size) */
size_t alloc_len; /* current number of bytes allocated */
size_t entropy; /* current entropy count in bits */
size_t entropy_requested; /* requested entropy count in bits */
};
/*
* The state of all types of DRBGs, even though we only have CTR mode
* right now.
*/
struct rand_drbg_st {
CRYPTO_RWLOCK *lock;
RAND_DRBG *parent;
int secure; /* 1: allocated on the secure heap, 0: otherwise */
int type; /* the nid of the underlying algorithm */
/*
* Stores the return value of openssl_get_fork_id() as of when we last
* reseeded. The DRBG reseeds automatically whenever drbg->fork_id !=
* openssl_get_fork_id(). Used to provide fork-safety and reseed this
* DRBG in the child process.
*/
int fork_id;
unsigned short flags; /* various external flags */
/*
* The random_data is used by RAND_add()/drbg_add() to attach random
* data to the global drbg, such that the rand_drbg_get_entropy() callback
* can pull it during instantiation and reseeding. This is necessary to
* reconcile the different philosophies of the RAND and the RAND_DRBG
* with respect to how randomness is added to the RNG during reseeding
* (see PR #4328).
*/
struct rand_pool_st *seed_pool;
/*
* Auxiliary pool for additional data.
*/
struct rand_pool_st *adin_pool;
/*
* The following parameters are setup by the per-type "init" function.
*
* Currently the only type is CTR_DRBG, its init function is drbg_ctr_init().
*
* The parameters are closely related to the ones described in
* section '10.2.1 CTR_DRBG' of [NIST SP 800-90Ar1], with one
* crucial difference: In the NIST standard, all counts are given
* in bits, whereas in OpenSSL entropy counts are given in bits
* and buffer lengths are given in bytes.
*
* Since this difference has lead to some confusion in the past,
* (see [GitHub Issue #2443], formerly [rt.openssl.org #4055])
* the 'len' suffix has been added to all buffer sizes for
* clarification.
*/
int strength;
size_t max_request;
size_t min_entropylen, max_entropylen;
size_t min_noncelen, max_noncelen;
size_t max_perslen, max_adinlen;
/* Counts the number of generate requests since the last reseed. */
unsigned int reseed_gen_counter;
/*
* Maximum number of generate requests until a reseed is required.
* This value is ignored if it is zero.
*/
unsigned int reseed_interval;
/* Stores the time when the last reseeding occurred */
time_t reseed_time;
/*
* Specifies the maximum time interval (in seconds) between reseeds.
* This value is ignored if it is zero.
*/
time_t reseed_time_interval;
/*
* Counts the number of reseeds since instantiation.
* This value is ignored if it is zero.
*
* This counter is used only for seed propagation from the <master> DRBG
* to its two children, the <public> and <private> DRBG. This feature is
* very special and its sole purpose is to ensure that any randomness which
* is added by RAND_add() or RAND_seed() will have an immediate effect on
* the output of RAND_bytes() resp. RAND_priv_bytes().
*/
TSAN_QUALIFIER unsigned int reseed_prop_counter;
unsigned int reseed_next_counter;
size_t seedlen;
DRBG_STATUS state;
/* Application data, mainly used in the KATs. */
CRYPTO_EX_DATA ex_data;
/* Implementation specific data (currently only one implementation) */
union {
RAND_DRBG_CTR ctr;
} data;
/* Implementation specific methods */
RAND_DRBG_METHOD *meth;
/* Callback functions. See comments in rand_lib.c */
RAND_DRBG_get_entropy_fn get_entropy;
RAND_DRBG_cleanup_entropy_fn cleanup_entropy;
RAND_DRBG_get_nonce_fn get_nonce;
RAND_DRBG_cleanup_nonce_fn cleanup_nonce;
};
/* The global RAND method, and the global buffer and DRBG instance. */
extern RAND_METHOD rand_meth;
/* DRBG helpers */
int rand_drbg_restart(RAND_DRBG *drbg,
const unsigned char *buffer, size_t len, size_t entropy);
size_t rand_drbg_seedlen(RAND_DRBG *drbg);
/* locking api */
int rand_drbg_lock(RAND_DRBG *drbg);
int rand_drbg_unlock(RAND_DRBG *drbg);
int rand_drbg_enable_locking(RAND_DRBG *drbg);
/* initializes the AES-CTR DRBG implementation */
int drbg_ctr_init(RAND_DRBG *drbg);
/*
* Entropy call back for the FIPS 140-2 section 4.9.2 Conditional Tests.
* These need to be exposed for the unit tests.
*/
int rand_crngt_get_entropy_cb(unsigned char *buf, unsigned char *md,
unsigned int *md_size);
extern int (*crngt_get_entropy)(unsigned char *buf, unsigned char *md,
unsigned int *md_size);
int rand_crngt_init(void);
void rand_crngt_cleanup(void);
/*
* Expose the run once initialisation function for the unit tests because.
* they need to restart from scratch to validate the first block is skipped
* properly.
*/
int rand_crngt_single_init(void);
#endif