/*
- * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
+ * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
*
- * Licensed under the OpenSSL license (the "License"). You may not use
+ * Licensed under the Apache License 2.0 (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
# include <openssl/sha.h>
# include <openssl/hmac.h>
# include <openssl/ec.h>
-# include "internal/rand.h"
+# include <openssl/rand_drbg.h>
+# include "internal/tsan_assist.h"
-/* Amount of randomness (in bytes) we want for initial seeding. */
-# define RANDOMNESS_NEEDED (128 / 8)
+# 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))
+ */
-/* Maximum count allowed in reseeding */
-#define MAX_RESEED (1 << 24)
/* DRBG status values */
-# define DRBG_STATUS_UNINITIALISED 0
-# define DRBG_STATUS_READY 1
-# define DRBG_STATUS_RESEED 2
-# define DRBG_STATUS_ERROR 3
+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);
-/* A default maximum length: larger than any reasonable value used in pratice */
-# define DRBG_MAX_LENGTH 0x7ffffff0
/*
- * The context for DRBG AES-CTR
+ * The DRBG methods
*/
-typedef struct drbg_ctr_ctx_st {
- AES_KEY ks;
+
+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;
+
+/* 888 bits from SP800-90Ar1 10.1 table 2 */
+#define HASH_PRNG_MAX_SEEDLEN (888/8)
+
+typedef struct rand_drbg_hash_st {
+ const EVP_MD *md;
+ EVP_MD_CTX *ctx;
+ size_t blocklen;
+ unsigned char V[HASH_PRNG_MAX_SEEDLEN];
+ unsigned char C[HASH_PRNG_MAX_SEEDLEN];
+ /* Temporary value storage: should always exceed max digest length */
+ unsigned char vtmp[HASH_PRNG_MAX_SEEDLEN];
+} RAND_DRBG_HASH;
+
+typedef struct rand_drbg_hmac_st {
+ const EVP_MD *md;
+ HMAC_CTX *ctx;
+ size_t blocklen;
+ unsigned char K[EVP_MAX_MD_SIZE];
+ unsigned char V[EVP_MAX_MD_SIZE];
+} RAND_DRBG_HMAC;
+
+/*
+ * 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];
- /* Temp variables used by derivation function */
- AES_KEY df_ks;
- AES_KEY df_kxks;
/* Temporary block storage used by ctr_df */
unsigned char bltmp[16];
size_t bltmp_pos;
unsigned char KX[48];
-} DRBG_CTR_CTX;
+} RAND_DRBG_CTR;
/*
- * The context for all DRBG's
+ * 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 drbg_ctx_st {
+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 */
+
+ size_t min_len; /* minimum number of random bytes requested */
+ size_t max_len; /* maximum number of random bytes (allocated buffer size) */
+ 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;
- DRBG_CTX *parent;
- int nid; /* the NID of the underlying algorithm */
- unsigned int flags; /* various external flags */
+ /* The library context this DRBG is associated with, if any */
+ OPENSSL_CTX *libctx;
+ RAND_DRBG *parent;
+ int secure; /* 1: allocated on the secure heap, 0: otherwise */
+ int type; /* the nid of the underlying algorithm */
+ /*
+ * Stores the value of the rand_fork_count global as of when we last
+ * reseeded. The DRBG reseeds automatically whenever drbg->fork_count !=
+ * rand_fork_count. Used to provide fork-safety and reseed this DRBG in
+ * the child process.
+ */
+ int fork_count;
+ 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.
+ *
+ * The supported types and their init functions are:
+ * (1) CTR_DRBG: drbg_ctr_init().
+ * (2) HMAC_DRBG: drbg_hmac_init().
+ * (3) HASH_DRBG: drbg_hash_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.
+ */
- /* The following parameters are setup by mechanism drbg_init() call */
int strength;
- size_t blocklength;
size_t max_request;
- size_t min_entropy, max_entropy;
- size_t min_nonce, max_nonce;
- size_t max_pers, max_adin;
- unsigned int reseed_counter;
+ 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
+ * (Starts at 1). This value is the reseed_counter as defined in
+ * NIST SP 800-90Ar1
+ */
+ 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;
- int status;
+ DRBG_STATUS state;
- /* Application data: typically (only?) used by test get_entropy */
+ /* Application data, mainly used in the KATs. */
CRYPTO_EX_DATA ex_data;
- /* Implementation specific structures */
- DRBG_CTR_CTX ctr;
+ /* Implementation specific data */
+ union {
+ RAND_DRBG_CTR ctr;
+ RAND_DRBG_HASH hash;
+ RAND_DRBG_HMAC hmac;
+ } data;
- /* entropy gathering function */
+ /* Implementation specific methods */
+ RAND_DRBG_METHOD *meth;
+
+ /* Callback functions. See comments in rand_lib.c */
RAND_DRBG_get_entropy_fn get_entropy;
- /* Indicates we have finished with entropy buffer */
RAND_DRBG_cleanup_entropy_fn cleanup_entropy;
- /* nonce gathering function */
RAND_DRBG_get_nonce_fn get_nonce;
- /* Indicates we have finished with nonce buffer */
RAND_DRBG_cleanup_nonce_fn cleanup_nonce;
};
+/* The global RAND method, and the global buffer and DRBG instance. */
+extern RAND_METHOD rand_meth;
+
+/*
+ * A "generation count" of forks. Incremented in the child process after a
+ * fork. Since rand_fork_count is increment-only, and only ever written to in
+ * the child process of the fork, which is guaranteed to be single-threaded, no
+ * locking is needed for normal (read) accesses; the rest of pthread fork
+ * processing is assumed to introduce the necessary memory barriers. Sibling
+ * children of a given parent will produce duplicate values, but this is not
+ * problematic because the reseeding process pulls input from the system CSPRNG
+ * and/or other global sources, so the siblings will end up generating
+ * different output streams.
+ */
+extern int rand_fork_count;
+
+/* 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);
+
-extern RAND_METHOD openssl_rand_meth;
-void rand_drbg_cleanup(void);
-
-/* Hardware-based seeding functions. */
-void rand_rdtsc(void);
-int rand_rdcpu(void);
-
-/* DRBG functions implementing AES-CTR */
-int ctr_init(DRBG_CTX *dctx);
-int ctr_uninstantiate(DRBG_CTX *dctx);
-int ctr_instantiate(DRBG_CTX *dctx,
- const unsigned char *ent, size_t entlen,
- const unsigned char *nonce, size_t noncelen,
- const unsigned char *pers, size_t perslen);
-int ctr_reseed(DRBG_CTX *dctx,
- const unsigned char *ent, size_t entlen,
- const unsigned char *adin, size_t adinlen);
-int ctr_generate(DRBG_CTX *dctx,
- unsigned char *out, size_t outlen,
- const unsigned char *adin, size_t adinlen);
+/* initializes the DRBG implementation */
+int drbg_ctr_init(RAND_DRBG *drbg);
+int drbg_hash_init(RAND_DRBG *drbg);
+int drbg_hmac_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(OPENSSL_CTX *ctx, unsigned char *buf,
+ unsigned char *md, unsigned int *md_size);
+extern int (*crngt_get_entropy)(OPENSSL_CTX *ctx, unsigned char *buf,
+ unsigned char *md,
+ unsigned int *md_size);
#endif
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