From: "Joy M. Latten" Subject: Re: [PATCH v2 03/11] crypto: Documentation - RNG API documentation Date: Wed, 05 Nov 2014 17:33:48 -0600 Message-ID: <1415230428.5083.41.camel@oc8377654763.ibm.com> References: <6375771.bx7QqLJLuR@tachyon.chronox.de> <5465244.OPD58DmVa6@tachyon.chronox.de> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: Herbert Xu , "David S. Miller" , Marek Vasut , Jason Cooper , Grant Likely , Geert Uytterhoeven , Linux Kernel Developers List , linux-crypto@vger.kernel.org To: Stephan Mueller Return-path: Received: from e8.ny.us.ibm.com ([32.97.182.138]:46665 "EHLO e8.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750860AbaKEXdx (ORCPT ); Wed, 5 Nov 2014 18:33:53 -0500 Received: from /spool/local by e8.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 5 Nov 2014 18:33:53 -0500 In-Reply-To: <5465244.OPD58DmVa6@tachyon.chronox.de> Sender: linux-crypto-owner@vger.kernel.org List-ID: Hi Stephan, Just one quick comment below... regards, Joy On Sun, 2014-11-02 at 21:36 +0100, Stephan Mueller wrote: > The API function calls exported by the kernel crypto API for RNGs to > be used by consumers are documented. > > Signed-off-by: Stephan Mueller > CC: Marek Vasut > --- > include/crypto/rng.h | 113 +++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 113 insertions(+) > > diff --git a/include/crypto/rng.h b/include/crypto/rng.h > index c93f9b9..83c4238 100644 > --- a/include/crypto/rng.h > +++ b/include/crypto/rng.h > @@ -20,11 +20,68 @@ extern struct crypto_rng *crypto_default_rng; > int crypto_get_default_rng(void); > void crypto_put_default_rng(void); > > +/** > + * Random number generator API to use the ciphers of type > + * CRYPTO_ALG_TYPE_RNG (listed as type "rng" in /proc/crypto) > + * > + * Example code: > + * > + *static int get_random_numbers(u8 *buf, unsigned int len) > + *{ > + * struct crypto_rng *rng = NULL; > + * char *drbg = "drbg_nopr_sha256"; // Hash DRBG with SHA-256, no PR > + * int ret; > + * > + * if (!buf || !len) { > + * pr_debug("No output buffer provided\n"); > + * return -EINVAL; > + * } > + * > + * rng = crypto_alloc_rng(drbg, 0, 0); > + * if (IS_ERR(rng)) { > + * pr_debug("could not allocate RNG handle for %s\n", drbg); > + * return -PTR_ERR(rng); > + * } > + * > + * ret = crypto_rng_get_bytes(rng, buf, len); > + * if (ret < 0) > + * pr_debug("generation of random numbers failed\n"); > + * else if (ret == 0) > + * pr_debug("RNG returned no data"); > + * else > + * pr_debug("RNG returned %d bytes of data\n", ret); > + * > + *out: > + * crypto_free_rng(rng); > + * return ret; > + *} > + */ > + > static inline struct crypto_rng *__crypto_rng_cast(struct crypto_tfm *tfm) > { > return (struct crypto_rng *)tfm; > } > > +/** > + * 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. > + * > + * @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 (see Documentation/crypto/) > + * @mask specifies the mask for the cipher (see Documentation/crypto/) > + * > + * return value: > + * allocated cipher handle in case of success > + * IS_ERR() is true in case of an error, PTR_ERR() returns the error code. > + */ > static inline struct crypto_rng *crypto_alloc_rng(const char *alg_name, > u32 type, u32 mask) > { > @@ -40,6 +97,14 @@ static inline struct crypto_tfm *crypto_rng_tfm(struct crypto_rng *tfm) > return &tfm->base; > } > > +/** > + * Return the generic name (cra_name) of the initialized random number generator > + * > + * @tfm cipher handle > + * > + * return value: > + * generic name string > + */ > static inline struct rng_alg *crypto_rng_alg(struct crypto_rng *tfm) > { > return &crypto_rng_tfm(tfm)->__crt_alg->cra_rng; > @@ -50,23 +115,71 @@ static inline struct rng_tfm *crypto_rng_crt(struct crypto_rng *tfm) > return &crypto_rng_tfm(tfm)->crt_rng; > } > > +/** > + * The referenced random number generator handle is zeroized and subsequently > + * freed. > + * > + * @tfm cipher handle to be freed > + */ > static inline void crypto_free_rng(struct crypto_rng *tfm) > { > crypto_free_tfm(crypto_rng_tfm(tfm)); > } > > +/** > + * This function fills the caller-allocated buffer with random numbers using the > + * random number generator referenced by the cipher handle. > + * > + * @tfm cipher handle > + * @rdata output buffer holding the random numbers > + * @dlen length of the output buffer > + * > + * return value: > + * > 0 function was successful and returns the number of generated bytes > + * < 0 if an error occurred > + */ > static inline int crypto_rng_get_bytes(struct crypto_rng *tfm, > u8 *rdata, unsigned int dlen) > { > return crypto_rng_crt(tfm)->rng_gen_random(tfm, rdata, dlen); > } > > +/** > + * 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 with the. The provided seed should have the length of dangling sentence... > + * the seed size defined for the random number generator as defined by > + * crypto_rng_seedsize. > + * > + * @tfm cipher handle > + * @seed seed input data > + * @slen length of the seed input data > + * > + * return value: > + * 0 if the setting of the key was successful > + * < 0 if an error occurred > + */ > static inline int crypto_rng_reset(struct crypto_rng *tfm, > u8 *seed, unsigned int slen) > { > return crypto_rng_crt(tfm)->rng_reset(tfm, seed, slen); > } > > +/** > + * 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. > + * > + * @tfm cipher handle > + * > + * return value: > + * seed size for the random number generator > + */ > static inline int crypto_rng_seedsize(struct crypto_rng *tfm) > { > return crypto_rng_alg(tfm)->seedsize;