1 /* 2 * RNG: Random Number Generator algorithms under the crypto API 3 * 4 * Copyright (c) 2008 Neil Horman <nhorman@tuxdriver.com> 5 * 6 * This program is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License as published by the Free 8 * Software Foundation; either version 2 of the License, or (at your option) 9 * any later version. 10 * 11 */ 12 13 #ifndef _CRYPTO_RNG_H 14 #define _CRYPTO_RNG_H 15 16 #include <linux/crypto.h> 17 18 extern struct crypto_rng *crypto_default_rng; 19 20 int crypto_get_default_rng(void); 21 void crypto_put_default_rng(void); 22 23 /** 24 * DOC: Random number generator API 25 * 26 * The random number generator API is used with the ciphers of type 27 * CRYPTO_ALG_TYPE_RNG (listed as type "rng" in /proc/crypto) 28 */ 29 30 static inline struct crypto_rng *__crypto_rng_cast(struct crypto_tfm *tfm) 31 { 32 return (struct crypto_rng *)tfm; 33 } 34 35 /** 36 * crypto_alloc_rng() -- allocate RNG handle 37 * @alg_name: is the cra_name / name or cra_driver_name / driver name of the 38 * message digest cipher 39 * @type: specifies the type of the cipher 40 * @mask: specifies the mask for the cipher 41 * 42 * Allocate a cipher handle for a random number generator. The returned struct 43 * crypto_rng is the cipher handle that is required for any subsequent 44 * API invocation for that random number generator. 45 * 46 * For all random number generators, this call creates a new private copy of 47 * the random number generator that does not share a state with other 48 * instances. The only exception is the "krng" random number generator which 49 * is a kernel crypto API use case for the get_random_bytes() function of the 50 * /dev/random driver. 51 * 52 * Return: allocated cipher handle in case of success; IS_ERR() is true in case 53 * of an error, PTR_ERR() returns the error code. 54 */ 55 static inline struct crypto_rng *crypto_alloc_rng(const char *alg_name, 56 u32 type, u32 mask) 57 { 58 type &= ~CRYPTO_ALG_TYPE_MASK; 59 type |= CRYPTO_ALG_TYPE_RNG; 60 mask |= CRYPTO_ALG_TYPE_MASK; 61 62 return __crypto_rng_cast(crypto_alloc_base(alg_name, type, mask)); 63 } 64 65 static inline struct crypto_tfm *crypto_rng_tfm(struct crypto_rng *tfm) 66 { 67 return &tfm->base; 68 } 69 70 /** 71 * crypto_rng_alg - obtain name of RNG 72 * @tfm: cipher handle 73 * 74 * Return the generic name (cra_name) of the initialized random number generator 75 * 76 * Return: generic name string 77 */ 78 static inline struct rng_alg *crypto_rng_alg(struct crypto_rng *tfm) 79 { 80 return &crypto_rng_tfm(tfm)->__crt_alg->cra_rng; 81 } 82 83 static inline struct rng_tfm *crypto_rng_crt(struct crypto_rng *tfm) 84 { 85 return &crypto_rng_tfm(tfm)->crt_rng; 86 } 87 88 /** 89 * crypto_free_rng() - zeroize and free RNG handle 90 * @tfm: cipher handle to be freed 91 */ 92 static inline void crypto_free_rng(struct crypto_rng *tfm) 93 { 94 crypto_free_tfm(crypto_rng_tfm(tfm)); 95 } 96 97 /** 98 * crypto_rng_get_bytes() - get random number 99 * @tfm: cipher handle 100 * @rdata: output buffer holding the random numbers 101 * @dlen: length of the output buffer 102 * 103 * This function fills the caller-allocated buffer with random numbers using the 104 * random number generator referenced by the cipher handle. 105 * 106 * Return: 0 function was successful; < 0 if an error occurred 107 */ 108 static inline int crypto_rng_get_bytes(struct crypto_rng *tfm, 109 u8 *rdata, unsigned int dlen) 110 { 111 return crypto_rng_crt(tfm)->rng_gen_random(tfm, rdata, dlen); 112 } 113 114 /** 115 * crypto_rng_reset() - re-initialize the RNG 116 * @tfm: cipher handle 117 * @seed: seed input data 118 * @slen: length of the seed input data 119 * 120 * The reset function completely re-initializes the random number generator 121 * referenced by the cipher handle by clearing the current state. The new state 122 * is initialized with the caller provided seed or automatically, depending 123 * on the random number generator type (the ANSI X9.31 RNG requires 124 * caller-provided seed, the SP800-90A DRBGs perform an automatic seeding). 125 * The seed is provided as a parameter to this function call. The provided seed 126 * should have the length of the seed size defined for the random number 127 * generator as defined by crypto_rng_seedsize. 128 * 129 * Return: 0 if the setting of the key was successful; < 0 if an error occurred 130 */ 131 static inline int crypto_rng_reset(struct crypto_rng *tfm, 132 u8 *seed, unsigned int slen) 133 { 134 return crypto_rng_crt(tfm)->rng_reset(tfm, seed, slen); 135 } 136 137 /** 138 * crypto_rng_seedsize() - obtain seed size of RNG 139 * @tfm: cipher handle 140 * 141 * The function returns the seed size for the random number generator 142 * referenced by the cipher handle. This value may be zero if the random 143 * number generator does not implement or require a reseeding. For example, 144 * the SP800-90A DRBGs implement an automated reseeding after reaching a 145 * pre-defined threshold. 146 * 147 * Return: seed size for the random number generator 148 */ 149 static inline int crypto_rng_seedsize(struct crypto_rng *tfm) 150 { 151 return crypto_rng_alg(tfm)->seedsize; 152 } 153 154 #endif 155