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/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
* RNG: Random Number Generator algorithms under the crypto API
*
* Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com>
* Copyright (c) 2015 Herbert Xu <herbert@gondor.apana.org.au>
*/
#ifndef _CRYPTO_RNG_H
#define _CRYPTO_RNG_H
#include <linux/crypto.h>
struct crypto_rng;
/**
* struct rng_alg - random number generator definition
*
* @generate: The function defined by this variable obtains a
* random number. The random number generator transform
* must generate the random number out of the context
* provided with this call, plus any additional data
* if provided to the call.
* @seed: Seed or reseed the random number generator. With the
* invocation of this function call, the random number
* generator shall become ready for generation. If the
* random number generator requires a seed for setting
* up a new state, the seed must be provided by the
* consumer while invoking this function. The required
* size of the seed is defined with @seedsize .
* @set_ent: Set entropy that would otherwise be obtained from
* entropy source. Internal use only.
* @seedsize: The seed size required for a random number generator
* initialization defined with this variable. Some
* random number generators does not require a seed
* as the seeding is implemented internally without
* the need of support by the consumer. In this case,
* the seed size is set to zero.
* @base: Common crypto API algorithm data structure.
*/
struct rng_alg {
int (*generate)(struct crypto_rng *tfm,
const u8 *src, unsigned int slen,
u8 *dst, unsigned int dlen);
int (*seed)(struct crypto_rng *tfm, const u8 *seed, unsigned int slen);
void (*set_ent)(struct crypto_rng *tfm, const u8 *data,
unsigned int len);
unsigned int seedsize;
struct crypto_alg base;
};
struct crypto_rng {
struct crypto_tfm base;
};
extern struct crypto_rng *crypto_default_rng;
int crypto_get_default_rng(void);
void crypto_put_default_rng(void);
/**
* DOC: Random number generator API
*
* The random number generator API is used with the ciphers of type
* CRYPTO_ALG_TYPE_RNG (listed as type "rng" in /proc/crypto)
*/
/**
* crypto_alloc_rng() -- allocate RNG handle
* @alg_name: is the cra_name / name or cra_driver_name / driver name of the
* message digest cipher
* @type: specifies the type of the cipher
* @mask: specifies the mask for the cipher
*
* Allocate a cipher handle for a random number generator. The returned struct
* crypto_rng is the cipher handle that is required for any subsequent
* API invocation for that random number generator.
*
* For all random number generators, this call creates a new private copy of
* the random number generator that does not share a state with other
* instances. The only exception is the "krng" random number generator which
* is a kernel crypto API use case for the get_random_bytes() function of the
* /dev/random driver.
*
* Return: allocated cipher handle in case of success; IS_ERR() is true in case
* of an error, PTR_ERR() returns the error code.
*/
struct crypto_rng *crypto_alloc_rng(const char *alg_name, u32 type, u32 mask);
static inline struct crypto_tfm *crypto_rng_tfm(struct crypto_rng *tfm)
{
return &tfm->base;
}
/**
* crypto_rng_alg - obtain name of RNG
* @tfm: cipher handle
*
* Return the generic name (cra_name) of the initialized random number generator
*
* Return: generic name string
*/
static inline struct rng_alg *crypto_rng_alg(struct crypto_rng *tfm)
{
return container_of(crypto_rng_tfm(tfm)->__crt_alg,
struct rng_alg, base);
}
/**
* crypto_free_rng() - zeroize and free RNG handle
* @tfm: cipher handle to be freed
*
* If @tfm is a NULL or error pointer, this function does nothing.
*/
static inline void crypto_free_rng(struct crypto_rng *tfm)
{
crypto_destroy_tfm(tfm, crypto_rng_tfm(tfm));
}
/**
* crypto_rng_generate() - get random number
* @tfm: cipher handle
* @src: Input buffer holding additional data, may be NULL
* @slen: Length of additional data
* @dst: output buffer holding the random numbers
* @dlen: length of the output buffer
*
* This function fills the caller-allocated buffer with random
* numbers using the random number generator referenced by the
* cipher handle.
*
* Return: 0 function was successful; < 0 if an error occurred
*/
static inline int crypto_rng_generate(struct crypto_rng *tfm,
const u8 *src, unsigned int slen,
u8 *dst, unsigned int dlen)
{
struct crypto_alg *alg = tfm->base.__crt_alg;
int ret;
crypto_stats_get(alg);
ret = crypto_rng_alg(tfm)->generate(tfm, src, slen, dst, dlen);
crypto_stats_rng_generate(alg, dlen, ret);
return ret;
}
/**
* crypto_rng_get_bytes() - get random number
* @tfm: cipher handle
* @rdata: output buffer holding the random numbers
* @dlen: length of the output buffer
*
* This function fills the caller-allocated buffer with random numbers using the
* random number generator referenced by the cipher handle.
*
* Return: 0 function was successful; < 0 if an error occurred
*/
static inline int crypto_rng_get_bytes(struct crypto_rng *tfm,
u8 *rdata, unsigned int dlen)
{
return crypto_rng_generate(tfm, NULL, 0, rdata, dlen);
}
/**
* crypto_rng_reset() - re-initialize the RNG
* @tfm: cipher handle
* @seed: seed input data
* @slen: length of the seed input data
*
* The reset function completely re-initializes the random number generator
* referenced by the cipher handle by clearing the current state. The new state
* is initialized with the caller provided seed or automatically, depending
* on the random number generator type (the ANSI X9.31 RNG requires
* caller-provided seed, the SP800-90A DRBGs perform an automatic seeding).
* The seed is provided as a parameter to this function call. The provided seed
* should have the length of the seed size defined for the random number
* generator as defined by crypto_rng_seedsize.
*
* Return: 0 if the setting of the key was successful; < 0 if an error occurred
*/
int crypto_rng_reset(struct crypto_rng *tfm, const u8 *seed,
unsigned int slen);
/**
* crypto_rng_seedsize() - obtain seed size of RNG
* @tfm: cipher handle
*
* The function returns the seed size for the random number generator
* referenced by the cipher handle. This value may be zero if the random
* number generator does not implement or require a reseeding. For example,
* the SP800-90A DRBGs implement an automated reseeding after reaching a
* pre-defined threshold.
*
* Return: seed size for the random number generator
*/
static inline int crypto_rng_seedsize(struct crypto_rng *tfm)
{
return crypto_rng_alg(tfm)->seedsize;
}
#endif
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