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