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Date:	Mon, 10 Mar 2014 10:36:28 -0300
From:	Rafael Aquini <aquini@...hat.com>
To:	Stephan Mueller <smueller@...onox.de>
Cc:	linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
	jeremy.wayne.powell@...il.com
Subject: Re: [PATCH 1/6] SP800-90A Deterministic Random Bit Generator

On Sun, Mar 09, 2014 at 12:46:00AM +0100, Stephan Mueller wrote:
> This is a clean-room implementation of the DRBG defined in SP800-90A.
> All three viable DRBGs defined in the standard are implemented:
> 
> 	* HMAC
> 	* Hash
> 	* CTR
> 
> Signed-off-by: Stephan Mueller <smueller@...onox.de>
> 
>  create mode 100644 crypto/drbg.c
> 
> diff --git a/crypto/drbg.c b/crypto/drbg.c
> new file mode 100644
> index 0000000..5308cce
> --- /dev/null
> +++ b/crypto/drbg.c
> @@ -0,0 +1,1941 @@
> +/*
> + * DRBG: Deterministic Random Bits Generator
> + *       Based on NIST Recommended DRBG from NIST SP800-90A with the following
> + *       properties:
> + *		* CTR DRBG with DF with AES-128, AES-192, AES-256 cores
> + * 		* Hash DRBG with DF with SHA-1, SHA-256, SHA-384, SHA-512 cores
> + * 		* HMAC DRBG with DF with SHA-1, SHA-256, SHA-384, SHA-512 cores
> + * 		* with and without prediction resistance
> + *
> + * Copyright Stephan Mueller <smueller@...onox.de>, 2014
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions
> + * are met:
> + * 1. Redistributions of source code must retain the above copyright
> + *    notice, and the entire permission notice in its entirety,
> + *    including the disclaimer of warranties.
> + * 2. Redistributions in binary form must reproduce the above copyright
> + *    notice, this list of conditions and the following disclaimer in the
> + *    documentation and/or other materials provided with the distribution.
> + * 3. The name of the author may not be used to endorse or promote
> + *    products derived from this software without specific prior
> + *    written permission.
> + *
> + * ALTERNATIVELY, this product may be distributed under the terms of
> + * the GNU General Public License, in which case the provisions of the GPL are
> + * required INSTEAD OF the above restrictions.  (This clause is
> + * necessary due to a potential bad interaction between the GPL and
> + * the restrictions contained in a BSD-style copyright.)
> + *
> + * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
> + * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
> + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ALL OF
> + * WHICH ARE HEREBY DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE
> + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
> + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
> + * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
> + * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
> + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
> + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
> + * USE OF THIS SOFTWARE, EVEN IF NOT ADVISED OF THE POSSIBILITY OF SUCH
> + * DAMAGE.
> + * 
> + * DRBG Usage
> + * ==========
> + * The SP 800-90A DRBG allows the user to specify a personalization string
> + * for initialization as well as an additional information string for each
> + * random number request. The following code fragments show how a caller
> + * uses the kernel crypto API to use the full functionality of the DRBG.
> + * 
> + * Usage without any additional data
> + * ---------------------------------
> + * struct crypto_rng *drng;
> + * int err;
> + * char data[DATALEN];
> + * 
> + * drng = crypto_alloc_rng(drng_name, 0, 0);
> + * err = crypto_rng_get_bytes(drng, &data, DATALEN);
> + * crypto_free_rng(drng);
> + * 
> + * 
> + * Usage with personalization string during initialization
> + * -------------------------------------------------------
> + * struct crypto_rng *drng;
> + * int err;
> + * char data[DATALEN];
> + * char personalization = "some-string";
> + * 
> + * drng = crypto_alloc_rng(drng_name, 0, 0);
> + * // The reset completely re-initializes the DRBG with the provided
> + * // personalization string
> + * err = crypto_rng_reset(drng, &personalization, strlen(personalization));
> + * err = crypto_rng_get_bytes(drng, &data, DATALEN);
> + * crypto_free_rng(drng);
> + * 
> + * 
> + * Usage with additional information string during random number request
> + * ---------------------------------------------------------------------
> + * struct crypto_rng *drng;
> + * int err;
> + * char data[DATALEN];
> + * char addtl = "some-string";
> + * 
> + * drng = crypto_alloc_rng(drng_name, 0, 0);
> + * // The following call is a wrapper to crypto_rng_get_bytes() and returns
> + * // the same error codes.
> + * err = crypto_drbg_get_bytes_addtl(drng,
> + *				     &data, DATALEN,
> + *				     &addtl, strlen(addtl));
> + * crypto_free_rng(drng);
> + * 
> + * 
> + * Usage with personalization and additional information strings
> + * -------------------------------------------------------------
> + * Just mix both scenarios above.
> + */
> +
> +#include <crypto/drbg.h>
> +
> +#if !defined(CONFIG_CRYPTO_DRBG_HASH) && \
> +	!defined(CONFIG_CRYPTO_DRBG_HMAC) && \
> +	!defined(CONFIG_CRYPTO_DRBG_CTR)
> +#warning "The DRBG code is useless without compiling at least one DRBG type"
> +#endif
> +
> +/***************************************************************
> + * Backend cipher definitions available to DRBG
> + ***************************************************************/
> +
> +#ifdef CONFIG_CRYPTO_DRBG_HMAC
> +static int drbg_kcapi_hmac(struct drbg_state *drbg, unsigned char *key,
> +			   unsigned char *outval, struct drbg_conc *in);
> +#endif /* CONFIG_CRYPTO_DRBG_HASH */
> +#if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
> +static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *key,
> +			   unsigned char *outval, struct drbg_conc *in);
> +static int drbg_init_hash_kernel(struct drbg_state *drbg);
> +static int drbg_fini_hash_kernel(struct drbg_state *drbg);
> +#endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
> +#ifdef CONFIG_CRYPTO_DRBG_CTR
> +static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *key,
> +			  unsigned char *outval, struct drbg_conc *in);
> +static int drbg_init_sym_kernel(struct drbg_state *drbg);
> +static int drbg_fini_sym_kernel(struct drbg_state *drbg);
> +#endif /* CONFIG_CRYPTO_DRBG_CTR */
> +
> +const struct drbg_core cores[] =
> +{
> +		/* Hash DRBGs */
> +#ifdef CONFIG_CRYPTO_DRBG_HASH
> +	{
> +		.flags = DRBG_HASHSHA1,
> +		.statelen = 55, /* 440 bits */
> +		.max_addtllen = 35,
> +		.max_bits = 19,
> +		.max_req = 48,
> +		.blocklen_bytes = 20,
> +		.cipher_fn = drbg_kcapi_hash,
> +		.init_lib = drbg_init_hash_kernel,
> +		.fini_lib = drbg_fini_hash_kernel,
> +		.cra_name = "sha1",
> +		.cra_driver_name = "sha1",
> +		.backend_cra_name = "sha1",
> +	}, {
> +		.flags = DRBG_HASHSHA256,
> +		.statelen = 55, /* 440 bits */
> +		.max_addtllen = 35,
> +		.max_bits = 19,
> +		.max_req = 48,
> +		.blocklen_bytes = 32,
> +		.cipher_fn = drbg_kcapi_hash,
> +		.init_lib = drbg_init_hash_kernel,
> +		.fini_lib = drbg_fini_hash_kernel,
> +		.cra_name = "sha256",
> +		.cra_driver_name = "sha256",
> +		.backend_cra_name = "sha256",
> +	}, {
> +		.flags = DRBG_HASHSHA384,
> +		.statelen = 111, /* 888 bits */
> +		.max_addtllen = 35,
> +		.max_bits = 19,
> +		.max_req = 48,
> +		.blocklen_bytes = 48,
> +		.cipher_fn = drbg_kcapi_hash,
> +		.init_lib = drbg_init_hash_kernel,
> +		.fini_lib = drbg_fini_hash_kernel,
> +		.cra_name = "sha384",
> +		.cra_driver_name = "sha384",
> +		.backend_cra_name = "sha384",
> +	}, {
> +		.flags = DRBG_HASHSHA512,
> +		.statelen = 111, /* 888 bits */
> +		.max_addtllen = 35,
> +		.max_bits = 19,
> +		.max_req = 48,
> +		.blocklen_bytes = 64,
> +		.cipher_fn = drbg_kcapi_hash,
> +		.init_lib = drbg_init_hash_kernel,
> +		.fini_lib = drbg_fini_hash_kernel,
> +		.cra_name = "sha512",
> +		.cra_driver_name = "sha512",
> +		.backend_cra_name = "sha512",
> +	},
> +#endif /* CONFIG_CRYPTO_DRBG_HASH */
> +#ifdef CONFIG_CRYPTO_DRBG_HMAC
> +	{
> +		/* HMAC DRBGs */
> +		.flags = DRBG_HMACSHA1,
> +		.statelen = 20, /* block length of cipher */
> +		.max_addtllen = 35,
> +		.max_bits = 19,
> +		.max_req = 48,
> +		.blocklen_bytes = 20,
> +		.cipher_fn = drbg_kcapi_hmac,
> +		.init_lib = drbg_init_hash_kernel,
> +		.fini_lib = drbg_fini_hash_kernel,
> +		.cra_name = "hmac(sha1)",
> +		.cra_driver_name = "hmac_sha1",
> +		.backend_cra_name = "hmac(sha1)",
> +	}, {
> +		.flags = DRBG_HMACSHA256,
> +		.statelen = 32, /* block length of cipher */
> +		.max_addtllen = 35,
> +		.max_bits = 19,
> +		.max_req = 48,
> +		.blocklen_bytes = 32,
> +		.cipher_fn = drbg_kcapi_hmac,
> +		.init_lib = drbg_init_hash_kernel,
> +		.fini_lib = drbg_fini_hash_kernel,
> +		.cra_name = "hmac(sha256)",
> +		.cra_driver_name = "hmac_sha256",
> +		.backend_cra_name = "hmac(sha256)",
> +	}, {
> +		.flags = DRBG_HMACSHA384,
> +		.statelen = 48, /* block length of cipher */
> +		.max_addtllen = 35,
> +		.max_bits = 19,
> +		.max_req = 48,
> +		.blocklen_bytes = 48,
> +		.cipher_fn = drbg_kcapi_hmac,
> +		.init_lib = drbg_init_hash_kernel,
> +		.fini_lib = drbg_fini_hash_kernel,
> +		.cra_name = "hmac(sha384)",
> +		.cra_driver_name = "hmac_sha384",
> +		.backend_cra_name = "hmac(sha384)",
> +	}, {
> +		.flags = DRBG_HMACSHA512,
> +		.statelen = 64, /* block length of cipher */
> +		.max_addtllen = 35,
> +		.max_bits = 19,
> +		.max_req = 48,
> +		.blocklen_bytes = 64,
> +		.cipher_fn = drbg_kcapi_hmac,
> +		.init_lib = drbg_init_hash_kernel,
> +		.fini_lib = drbg_fini_hash_kernel,
> +		.cra_name = "hmac(sha512)",
> +		.cra_driver_name = "hmac_sha512",
> +		.backend_cra_name = "hmac(sha512)",
> +	},
> +#endif /* CONFIG_CRYPTO_DRBG_HMAC */
> +#ifdef CONFIG_CRYPTO_DRBG_CTR
> +	{
> +		/* block ciphers */
> +		.flags = DRBG_CTRAES128,
> +		.statelen = 32, /* 256 bits as defined in 10.2.1 */
> +		.max_addtllen = 35,
> +		.max_bits = 19,
> +		.max_req = 48,
> +		.blocklen_bytes = 16,
> +		.cipher_fn = drbg_kcapi_sym,
> +		.init_lib = drbg_init_sym_kernel,
> +		.fini_lib = drbg_fini_sym_kernel,
> +		.cra_name = "ctr(aes128)",
> +		.cra_driver_name = "ctr_aes128",
> +		.backend_cra_name = "ecb(aes)",
> +		
> +	}, {
> +		/* block ciphers */
> +		.flags = DRBG_CTRAES192,
> +		.statelen = 40, /* 320 bits as defined in 10.2.1 */
> +		.max_addtllen = 35,
> +		.max_bits = 19,
> +		.max_req = 48,
> +		.blocklen_bytes = 16,
> +		.cipher_fn = drbg_kcapi_sym,
> +		.init_lib = drbg_init_sym_kernel,
> +		.fini_lib = drbg_fini_sym_kernel,
> +		.cra_name = "ctr(aes192)",
> +		.cra_driver_name = "ctr_aes192",
> +		.backend_cra_name = "ecb(aes)",
> +	}, {
> +		/* block ciphers */
> +		.flags = DRBG_CTRAES256,
> +		.statelen = 48, /* 384 bits as defined in 10.2.1 */
> +		.max_addtllen = 35,
> +		.max_bits = 19,
> +		.max_req = 48,
> +		.blocklen_bytes = 16,
> +		.cipher_fn = drbg_kcapi_sym,
> +		.init_lib = drbg_init_sym_kernel,
> +		.fini_lib = drbg_fini_sym_kernel,
> +		.cra_name = "ctr(aes256)",
> +		.cra_driver_name = "ctr_aes256",
> +		.backend_cra_name = "ecb(aes)",
> +	},
> +#endif /* CONFIG_CRYPTO_DRBG_CTR */
> +};
> +
> +/******************************************************************
> + * Generic helper functions
> + ******************************************************************/
> +
> +/*
> + * Return strength of DRBG according to SP800-90A section 8.4
> + *
> + * flags: DRBG flags reference
> + *
> + * Return: normalized strength value or 0 on error
> + */
> +static unsigned short drbg_sec_strength(drbg_flag_t flags)
> +{
> +	switch(flags & DRBG_CIPHER_MASK) {
> +		case DRBG_CTRAES128:
> +		case DRBG_CTRSERPENT128:
> +		case DRBG_CTRTWOFISH128:
> +		case DRBG_HASHSHA1:
> +		case DRBG_HMACSHA1:
> +			return 128;
> +		case DRBG_CTRAES192:
> +		case DRBG_CTRSERPENT192:
> +		case DRBG_CTRTWOFISH192:
> +			return 192;
> +		case DRBG_CTRAES256:
> +		case DRBG_CTRSERPENT256:
> +		case DRBG_CTRTWOFISH256:
> +		case DRBG_HASHSHA256:
> +		case DRBG_HASHSHA384:
> +		case DRBG_HASHSHA512:
> +		case DRBG_HMACSHA256:
> +		case DRBG_HMACSHA384:
> +		case DRBG_HMACSHA512:
> +			return 256;
> +		default:
> +			return 0;
> +	}
> +}
> +
> +#if (defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR))
> +static inline void drbg_int2byte(unsigned char *buf, uint64_t val, size_t buflen)
> +{
> +	unsigned char *byte;
> +	uint64_t i;
> +
> +	byte = buf + (buflen - 1);
> +	for (i = 0; i < buflen; i++)
> +		*(byte--) = val >> (i * 8) & 0xff;
> +}
> +
> +static inline void drbg_add_buf(unsigned char *dst, size_t dstlen,
> +				unsigned char *add, size_t addlen)
> +{
> +	/* implied: dstlen > addlen */
> +	unsigned char *dstptr, *addptr;
> +	unsigned int remainder = 0;
> +	size_t len = addlen;
> +
> +	dstptr = dst + (dstlen-1);
> +	addptr = add + (addlen-1);
> +	while(len) {
> +		remainder += *dstptr + *addptr;
> +		*dstptr = remainder & 0xff;
> +		remainder >>= 8;
> +		len--; dstptr--; addptr--;
> +	}
> +	len = dstlen - addlen;
> +	while(len && remainder > 0) {
> +		remainder = *dstptr + 1;
> +		*dstptr = remainder & 0xff;
> +		remainder >>= 8;
> +		len--; dstptr--;
> +	}
> +}
> +#endif /* defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR) */
> +
> +/******************************************************************
> + * CTR DRBG callback functions
> + ******************************************************************/
> +
> +#ifdef CONFIG_CRYPTO_DRBG_CTR
> +static int drbg_ctr_bcc(struct drbg_state *drbg,
> +			unsigned char *out, unsigned char *key,
> +			struct drbg_conc *in)
> +{
> +	int ret = -EFAULT;
> +	struct drbg_conc *curr = in;
> +	size_t inpos = curr->len;
> +	unsigned char *pos = curr->in;
> +	struct drbg_conc data;
> +
> +	DRBG_CLEAR_CONC(data);
> +	data.in = out;
> +	data.len = DRBG_BLOCKLEN(drbg);
> +
> +	/* 10.4.3 step 1 */
> +	memset(out, 0, DRBG_BLOCKLEN(drbg));
> +
> +	/* 10.4.3 step 2 / 4 */
> +	while(inpos) {
> +		short cnt = 0;
> +		/* 10.4.3 step 4.1 */
> +		for(cnt = 0; cnt < DRBG_BLOCKLEN(drbg); cnt++) {
> +			out[cnt] ^= *pos;
> +			pos++; inpos--;
> +			/* the following branch implements the linked list
> +			 * iteration. If we are at the end of the current data
> +			 * set, we have to start using the next data set if
> +			 * available -- the inpos value always points to the
> +			 * current byte and will be zero if we have processed
> +			 * the last byte of the last linked list member */
> +			if(0 == inpos) {
> +				curr = curr->next;
> +				if(NULL != curr) {
> +					pos = curr->in;
> +					inpos = curr->len;
> +				} else {
> +					inpos = 0;
> +					break;
> +				}
> +			}
> +		}
> +		/* 10.4.3 step 4.2 */
> +		ret = drbg->core->cipher_fn(drbg, key, out, &data);
> +		if(ret)
> +			return ret;
> +		/* 10.4.3 step 2 */
> +	}
> +	return 0;
> +}
> +
> +static int drbg_ctr_df(struct drbg_state *drbg,
> +		       unsigned char *out, size_t bytes_to_return,
> +		       struct drbg_conc *input)
> +{
> +	int ret = -EFAULT;
> +	unsigned char L_N[8];
> +	/* S3 is input */
> +	struct drbg_conc S1, S2, S4;
> +	unsigned char temp[DRBG_CTR_BLK], pad[DRBG_CTR_BLK], IV[DRBG_CTR_BLK];
> +	size_t padlen = 1; /* already reserve space for 0x80 */
> +	int templen = 0;
> +	/* 10.4.2 step 7 */
> +	unsigned int i = 0;
> +	/* 10.4.2 step 8 - truncation happens in ->cipher_fn which uses only
> +	 * DRBG_BLOCKLEN bits of key */
> +	unsigned char *K = (unsigned char *)
> +			   "\x00\x01\x02\x03\x04\x05\x06\x07"
> +			   "\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f"
> +			   "\x10\x11\x12\x13\x14\x15\x16\x17"
> +			   "\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f";
> +	unsigned char *X;
> +	struct drbg_conc cipherin;
> +	size_t generated_len = 0;
> +	size_t inputlen = 0;
> +	struct drbg_conc *tempconc = input;
> +
> +	DRBG_CLEAR_CTR_BLK(pad);
> +	DRBG_CLEAR_CTR_BLK(temp);
> +	DRBG_CLEAR_CTR_BLK(IV);
> +	DRBG_CLEAR_CONC(S1);
> +	DRBG_CLEAR_CONC(S2);
> +	DRBG_CLEAR_CONC(S4);
> +
> +	/* 10.4.2 step 1 is implicit as we work byte-wise*/
> +
> +	/* 10.4.2 step 2 */
> +	if((512/8) < bytes_to_return)
> +		return -EINVAL;
> +
> +	/* 10.4.2 step 2 -- calculate the entire length of all input data*/
> +	for(; NULL != tempconc; tempconc = tempconc->next)
> +		inputlen += tempconc->len;
> +
> +	drbg_int2byte(&L_N[0], inputlen, 4);
> +	/* 10.4.2 step 3 */
> +	drbg_int2byte(&L_N[4], bytes_to_return, 4);
> +
> +	/* 10.4.2 step 5: length is L_N, input_string, one byte, padding */
> +	while(0 != ((8 + inputlen + padlen) % (DRBG_BLOCKLEN(drbg))))
> +		padlen++;
> +	pad[0] = 0x80;
> +
> +	/* 10.4.2 step 4 -- first arrange the linked list and then fill it */
> +	S1.next = &S2;
> +	S2.next = input;
> +	/* splice in input between S2 and S4 -- we place S4 at the end of the
> +	 * input data chain */
> +	tempconc = input;
> +	for(; NULL != tempconc; tempconc = tempconc->next)
> +		if(NULL == tempconc->next)
> +			break;
> +	tempconc->next = &S4;
> +
> +	S1.in = IV;
> +	S1.len = DRBG_BLOCKLEN(drbg);
> +	S2.in = L_N;
> +	S2.len = 8;
> +	S4.in = pad;
> +	S4.len = padlen;
> +
> +	/* 10.4.2 step 9 */
> +	while(templen < (DRBG_KEYLEN(drbg) + (DRBG_BLOCKLEN(drbg)))) {
> +		/* 10.4.2 step 9.1 - the padding is implicit as the buffer
> +		 * holds zeros after allocation -- even the increment of i
> +		 * is irrelevant as the increment remains within length of i */
> +		drbg_int2byte(IV, i, 4);
> +		/* 10.4.2 step 9.2 -- BCC and concatenation with temp */
> +		ret = drbg_ctr_bcc(drbg, temp + templen, K, &S1);
> +		if(ret)
> +			goto out;
> +		/* 10.4.2 step 9.3 */
> +		i++;
> +		templen += DRBG_BLOCKLEN(drbg);
> +	}
> +
> +	/* 10.4.2 step 11 */
> +	/* implicit key len with seedlen - blocklen according to table 3 */
> +	X = temp + (DRBG_KEYLEN(drbg));
> +	cipherin.in = X; cipherin.len = DRBG_BLOCKLEN(drbg);
> +
> +	/* 10.4.2 step 12: overwriting of outval */
> +
> +	/* 10.4.2 step 13 */
> +	while(generated_len < bytes_to_return) {
> +		short blocklen = 0;
> +		/* 10.4.2 step 13.1 */
> +		/* the truncation of the key length is implicit as the key
> +		 * is only DRBG_BLOCKLEN in size -- check for the implementation
> +		 * of the cipher function callback */
> +		ret = drbg->core->cipher_fn(drbg, temp, X, &cipherin);
> +		if(ret)
> +			goto out;
> +		blocklen = (DRBG_BLOCKLEN(drbg) <
> +				(bytes_to_return - generated_len)) ?
> +			    DRBG_BLOCKLEN(drbg) :
> +				(bytes_to_return - generated_len);
> +		/* 10.4.2 step 13.2 and 14 */
> +		memcpy(out + generated_len, X, blocklen);
> +		generated_len += blocklen;
> +	}
> +
> +	ret = 0;
> +
> +out:
> +	DRBG_CLEAR_CTR_BLK(IV);
> +	DRBG_CLEAR_CTR_BLK(temp);
> +	DRBG_CLEAR_CTR_BLK(pad);
> +	return ret;
> +}
> +
> +static int drbg_ctr_update_state(struct drbg_state *drbg,
> +				 struct drbg_conc *prov_data,
> +				 int reseed)
> +{
> +	int ret = -EFAULT;
> +	/* 10.2.1.2 step 1 */
> +	unsigned char temp[DRBG_CTR_BLK], df_data[DRBG_CTR_BLK];
> +	unsigned char *temp_p, *df_data_p; /* not malloced */
> +	int len = 0;
> +	struct drbg_conc cipherin;
> +
> +	DRBG_CLEAR_CTR_BLK(temp);
> +	DRBG_CLEAR_CTR_BLK(df_data);
> +	DRBG_CLEAR_CONC(cipherin);
> +
> +	/* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */
> +	if(0 < prov_data->len) {
> +		ret = drbg_ctr_df(drbg, df_data, DRBG_STATELEN(drbg),
> +				  prov_data);
> +		if(ret)
> +			goto out;
> +	}
> +
> +	cipherin.in = drbg->V; cipherin.len = DRBG_BLOCKLEN(drbg);
> +	/* 10.2.1.3.2 step 2 and 3 -- are already covered as we memset(0)
> +	 * all memory during initialization */
> +	while(len < (DRBG_STATELEN(drbg))) {
> +		/* 10.2.1.2 step 2.1 */
> +		drbg_add_buf(drbg->V, DRBG_BLOCKLEN(drbg),
> +			     (unsigned char *) "\1", 1);
> +		/* 10.2.1.2 step 2.2 */
> +		/* using target of temp + len: 10.2.1.2 step 2.3 and 3 */
> +		ret = drbg->core->cipher_fn(drbg, drbg->C, temp + len,
> +					    &cipherin);
> +		if(ret)
> +			goto out;
> +		/* 10.2.1.2 step 2.3 and 3 */
> +		len += DRBG_BLOCKLEN(drbg);
> +	}
> +
> +	/* 10.2.1.2 step 4 */
> +	temp_p = temp;
> +	df_data_p = df_data;
> +	for(len = 0; len < DRBG_STATELEN(drbg); len++) {
> +		*temp_p ^= *df_data_p;
> +		df_data_p++; temp_p++;
> +	}
> +
> +	/* 10.2.1.2 step 5 */
> +	memcpy(drbg->C, temp, DRBG_KEYLEN(drbg));
> +	/* 10.2.1.2 step 6 */
> +	memcpy(drbg->V, temp + DRBG_KEYLEN(drbg), DRBG_BLOCKLEN(drbg));
> +	ret = 0;
> +
> +out:
> +	DRBG_CLEAR_CTR_BLK(df_data);
> +	DRBG_CLEAR_CTR_BLK(temp);
> +	return ret;
> +}
> +
> +static int drbg_ctr_process_addtl(struct drbg_state *drbg,
> +				  unsigned char *addtl_input, size_t addtllen)
> +{
> +	struct drbg_conc addtl;
> +	DRBG_CLEAR_CONC(addtl);
> +	if(0 == addtllen)
> +		return 0;
> +	/* 10.2.1.5.2 step 2 */
> +	addtl.in = addtl_input;
> +	addtl.len = addtllen;
> +	return drbg_ctr_update_state(drbg, &addtl, 1);
> +}
> +
> +static int drbg_ctr_preprocess_extract(struct drbg_state *drbg,
> +				       unsigned char **src,
> +				       unsigned char **dst,
> +				       short *length)
> +{
> +	memset(drbg->scratchpad, 0, DRBG_BLOCKLEN(drbg));
> +	*src = drbg->V;
> +	*dst = (unsigned char *)drbg->scratchpad;
> +	*length = DRBG_BLOCKLEN(drbg);
> +
> +	drbg_add_buf(*src, DRBG_BLOCKLEN(drbg),
> +		     (unsigned char *) "\1", 1);
> +
> +	return 0;
> +}
> +
> +static void drbg_ctr_postprocess_extract(struct drbg_state *drbg,
> +					 unsigned char *src,
> +					 unsigned char *dst, int notlast)
> +{
> +	/* 10.2.1.5.2 step 4.1 */
> +	if(notlast)
> +		drbg_add_buf(src, DRBG_BLOCKLEN(drbg),
> +			     (unsigned char *) "\1", 1);
> +}
> +
> +static void drbg_ctr_cleanup_extract(struct drbg_state *drbg,
> +				     unsigned char **src,
> +				     unsigned char **dst)
> +{
> +	memset(drbg->scratchpad, 0, DRBG_BLOCKLEN(drbg));
> +}
> +
> +static int drbg_ctr_newstate_postgen(struct drbg_state *drbg,
> +				     unsigned char *addtl_input,
> +				     size_t addtllen)
> +{
> +	struct drbg_conc addtl;
> +	DRBG_CLEAR_CONC(addtl);
> +	addtl.in = addtl_input;
> +	addtl.len = addtllen;
> +	/* 10.1.2.5 step 6 */
> +	/*TODO the DF function is called again since according to step
> +	 * 2, the "additional_input" after step 2 is the output of the DF
> +	 * function -- when we save the DF output as a replacement
> +	 * for the addtl_input data, we do not need to call the DF again here*/
> +	return drbg_ctr_update_state(drbg, &addtl, 1);
> +}
> +
> +static struct drbg_state_ops drbg_ctr_ops = {
> +	.process_addtl       = drbg_ctr_process_addtl,
> +	.preprocess_extract  = drbg_ctr_preprocess_extract,
> +	.postprocess_extract = drbg_ctr_postprocess_extract,
> +	.cleanup_extract     = drbg_ctr_cleanup_extract,
> +	.newstate_postgen    = drbg_ctr_newstate_postgen,
> +	.update_state        = drbg_ctr_update_state,
> +};
> +#endif /* CONFIG_CRYPTO_DRBG_CTR */
> +
> +/******************************************************************
> + * HMAC DRBG callback functions
> + ******************************************************************/
> +
> +#ifdef CONFIG_CRYPTO_DRBG_HMAC
> +static int drbg_hmac_update_state(struct drbg_state *drbg,
> +				  struct drbg_conc *seed,
> +				  int reseed)
> +{
> +	int ret = -EFAULT;
> +	int i = 0;
> +	struct drbg_conc seed1, seed2, cipherin;
> +
> +	DRBG_CLEAR_CONC(seed1);
> +	DRBG_CLEAR_CONC(seed2);
> +	DRBG_CLEAR_CONC(cipherin);
> +
> +	if(!reseed) {
> +		/* 10.1.2.3 step 2 already implicitly covered with
> +		 * the initial memset(0) of drbg->C */
> +		memset(drbg->C, 0, DRBG_STATELEN(drbg));
> +		memset(drbg->V, 1, DRBG_STATELEN(drbg));
> +	}
> +
> +	/* build linked list which implements the concatenation and fill
> +	 * first part*/
> +	seed1.next = &seed2;
> +	seed2.next = seed;
> +	seed1.in = drbg->V;
> +	seed1.len = DRBG_STATELEN(drbg);
> +
> +	cipherin.in = drbg->V;
> +	cipherin.len = DRBG_STATELEN(drbg);
> +	/* we execute two rounds of V/K massaging */
> +	for(i = 2; 0 < i; i--) {
> +		/* first round uses 0x0, second 0x1 */
> +		unsigned char prefix = '\0';
> +		if(1 == i)
> +			prefix = '\1';
> +
> +		/* 10.1.2.2 step 1 and 4 -- concatenation and HMAC for key */
> +		seed2.in = &prefix;
> +		seed2.len = 1;
> +		ret = drbg->core->cipher_fn(drbg, drbg->C, drbg->C, &seed1);
> +		if(ret)
> +			return ret;
> +
> +		/* 10.1.2.2 step 2 and 5 -- HMAC for V */
> +		ret = drbg->core->cipher_fn(drbg, drbg->C, drbg->V, &cipherin);
> +		if(ret)
> +			return ret;
> +
> +		/* 10.1.2.2 step 3 */
> +		if(0 == seed->len)
> +			return ret;
> +	}
> +	ret = 0;
> +
> +	return ret;
> +}
> +
> +static int drbg_hmac_process_addtl(struct drbg_state *drbg,
> +				   unsigned char *addtl_input, size_t addtllen)
> +{
> +	struct drbg_conc addtl;
> +	DRBG_CLEAR_CONC(addtl);
> +	if(0 == addtllen)
> +		return 0;
> +	addtl.in = addtl_input;
> +	addtl.len = addtllen;
> +	/* 10.1.2.5 step 2 */
> +	return drbg_hmac_update_state(drbg, &addtl, 1);
> +}
> +
> +static int drbg_hmac_preprocess_extract(struct drbg_state *drbg,
> +					unsigned char **src,
> +					unsigned char **dst,
> +					short *length)
> +{
> +	*src = drbg->V;
> +	*dst = drbg->V;
> +	*length = DRBG_STATELEN(drbg);
> +	return 0;
> +}
> +static void drbg_hmac_postprocess_extract(struct drbg_state *drbg,
> +					  unsigned char *src,
> +					  unsigned char *dst, int notlast)
> +{
> +	/* nothing needed */
> +}
> +
> +static void drbg_hmac_cleanup_extract(struct drbg_state *drbg,
> +				      unsigned char **src,
> +				      unsigned char **dst)
> +{
> +	/* nothing needed */
> +}
> +
> +static int drbg_hmac_newstate_postgen(struct drbg_state *drbg,
> +				      unsigned char *addtl_input,
> +				      size_t addtllen)
> +{
> +	struct drbg_conc addtl;
> +	DRBG_CLEAR_CONC(addtl);
> +	addtl.in = addtl_input;
> +	addtl.len = addtllen;
> +	/* 10.1.2.5 step 6 */
> +	return drbg_hmac_update_state(drbg, &addtl, 1);
> +}
> +
> +static struct drbg_state_ops drbg_hmac_ops = {
> +	.process_addtl       = drbg_hmac_process_addtl,
> +	.preprocess_extract  = drbg_hmac_preprocess_extract,
> +	.postprocess_extract = drbg_hmac_postprocess_extract,
> +	.cleanup_extract     = drbg_hmac_cleanup_extract,
> +	.newstate_postgen    = drbg_hmac_newstate_postgen,
> +	.update_state        = drbg_hmac_update_state,
> +};
> +#endif /* CONFIG_CRYPTO_DRBG_HMAC */
> +
> +/******************************************************************
> + * Hash DRBG callback functions
> + ******************************************************************/
> +
> +#ifdef CONFIG_CRYPTO_DRBG_HASH
> +static int drbg_hash_df(struct drbg_state *drbg,
> +			unsigned char *outval, size_t outlen,
> +			struct drbg_conc *entropy)
> +{
> +	int ret = 0;
> +	/* 10.1.1.4 step 1 */
> +	size_t len = 0;
> +	unsigned char tmp[DRBG_HASH_BLK], input[5];
> +	struct drbg_conc data1;
> +
> +	DRBG_CLEAR_HASH_BLK(tmp);
> +	DRBG_CLEAR_CONC(data1);
> +
> +	/* 10.4.1 step 3 */
> +	input[0] = 1;
> +	drbg_int2byte(&input[1], (outlen * 8), 4);
> +
> +	/* 10.4.1 step 4.1 -- concatenation of data for input into hash */
> +	data1.next = entropy;
> +	data1.in = input;
> +	data1.len = 5;
> +
> +	/* 10.4.1 step 4 */
> +	while(len < outlen) {
> +		short blocklen = 0;
> +		/* 10.4.1 step 4.1 */
> +		ret = drbg->core->cipher_fn(drbg, NULL, tmp, &data1);
> +		if(ret) {
> +			memset(outval, 0, outlen);
> +			goto out;
> +		}
> +		/* 10.4.1 step 4.2 */
> +		input[0]++;
> +		blocklen = (DRBG_BLOCKLEN(drbg) < (outlen - len)) ?
> +			    DRBG_BLOCKLEN(drbg) : (outlen - len);
> +		memcpy(outval + len, tmp, blocklen);
> +		len += blocklen;
> +	}
> +
> +out:
> +	DRBG_CLEAR_HASH_BLK(tmp);
> +	return ret;
> +}
> +
> +static int drbg_hash_update_state(struct drbg_state *drbg,
> +				  struct drbg_conc *seed,
> +				  int reseed)
> +{
> +	int ret = 0;
> +	struct drbg_conc data1, data2;
> +	unsigned char V[DRBG_HASH_BLK];
> +
> +	DRBG_CLEAR_HASH_BLK(V);
> +	DRBG_CLEAR_CONC(data1);
> +	DRBG_CLEAR_CONC(data2);
> +
> +	if(reseed) {
> +		/* 10.1.1.3 step 1: string length is concatenation of
> +		 * 1 byte, V and seed (which is concatenated entropy/addtl
> +		 * input)
> +		 */
> +		memcpy(V, drbg->V, DRBG_STATELEN(drbg));
> +		data1.next = &data2;
> +		data2.next = seed;
> +		data1.in = (unsigned char *)"\1";
> +		data1.len = 1;
> +		data2.in = V;
> +		data2.len = DRBG_STATELEN(drbg);
> +	} else {
> +		data1.in = seed->in;
> +		data1.len = seed->len;
> +		data1.next = seed->next;
> +	}
> +
> +	/* 10.1.1.2 / 10.1.1.3 step 2 and 3 */
> +	ret = drbg_hash_df(drbg, drbg->V, DRBG_STATELEN(drbg), &data1);
> +	if(ret)
> +		goto out;
> +
> +	/* 10.1.1.2 / 10.1.1.3 step 4 -- concatenation  */
> +	data1.next = &data2;
> +	data2.next = NULL;
> +	data1.in = (unsigned char *)"\0";
> +	data1.len = 1;
> +	data2.in = drbg->V;
> +	data2.len = DRBG_STATELEN(drbg);
> +	/* 10.1.1.2 / 10.1.1.3 step 4 -- df operation */
> +	ret = drbg_hash_df(drbg, drbg->C, DRBG_STATELEN(drbg), &data1);
> +
> +out:
> +	DRBG_CLEAR_HASH_BLK(V);
> +	return ret;
> +}
> +
> +static int drbg_hash_process_addtl(struct drbg_state *drbg,
> +			      unsigned char *addtl_input, size_t addtllen)
> +{
> +	int ret = 0;
> +	unsigned char w[DRBG_HASH_BLK];
> +	struct drbg_conc data1, data2, data3;
> +
> +	DRBG_CLEAR_HASH_BLK(w);
> +	DRBG_CLEAR_CONC(data1);
> +	DRBG_CLEAR_CONC(data2);
> +	DRBG_CLEAR_CONC(data3);
> +
> +	/* 10.1.1.4 step 2 */
> +	if(0 == addtllen)
> +		return 0;
> +
> +	/* 10.1.1.4 step 2a -- concatenation */
> +	data1.next = &data2;
> +	data2.next = &data3;
> +	data1.in = (unsigned char *) "\2";
> +	data1.len = 1;
> +	data2.in = drbg->V;
> +	data2.len = DRBG_STATELEN(drbg);
> +	data3.in = addtl_input;
> +	data3.len = addtllen;
> +	/* 10.1.1.4 step 2a -- cipher invocation */
> +	ret = drbg->core->cipher_fn(drbg, NULL, w, &data1);
> +	if(ret)
> +		goto out;
> +
> +	/* 10.1.1.4 step 2b */
> +	drbg_add_buf(drbg->V, DRBG_STATELEN(drbg), w, DRBG_BLOCKLEN(drbg));
> +
> +out:
> +	DRBG_CLEAR_HASH_BLK(w);
> +	return ret;
> +}
> +
> +static int drbg_hash_preprocess_extract(struct drbg_state *drbg,
> +					unsigned char **src,
> +					unsigned char **dst,
> +					short *length)
> +{
> +	memset(drbg->scratchpad, 0,
> +	       (DRBG_STATELEN(drbg) + DRBG_BLOCKLEN(drbg)));
> +	memcpy(drbg->scratchpad, drbg->V, DRBG_STATELEN(drbg));
> +
> +	*src = (unsigned char *)drbg->scratchpad;
> +	*dst = (unsigned char *)drbg->scratchpad + DRBG_STATELEN(drbg);
> +	*length = DRBG_STATELEN(drbg);
> +
> +	return 0;
> +}
> +
> +static void drbg_hash_postprocess_extract(struct drbg_state *drbg,
> +					  unsigned char *src,
> +					  unsigned char *dst, int notlast)
> +{
> +	/* 10.1.1.4 hashgen step 4.3 */
> +	if(notlast)
> +		drbg_add_buf(src, DRBG_STATELEN(drbg),
> +			     (unsigned char *) "\1", 1);
> +}
> +
> +static void drbg_hash_cleanup_extract(struct drbg_state *drbg,
> +				      unsigned char **src,
> +				      unsigned char **dst)
> +{
> +	memset(drbg->scratchpad, 0,
> +	       (DRBG_STATELEN(drbg) + DRBG_BLOCKLEN(drbg)));
> +}
> +
> +static int drbg_hash_newstate_postgen(struct drbg_state *drbg,
> +				      unsigned char *addtl_input,
> +				      size_t addtllen)
> +{
> +	int ret = 0;
> +	unsigned char req[8], H[DRBG_HASH_BLK];
> +	struct drbg_conc data1, data2;
> +
> +	DRBG_CLEAR_HASH_BLK(H);
> +	DRBG_CLEAR_CONC(data1);
> +	DRBG_CLEAR_CONC(data2);
> +
> +	/* 10.1.1.4 step 4 */
> +	data1.next = &data2;
> +	data1.in = (unsigned char *) "\3";
> +	data1.len = 1;
> +	data2.in = drbg->V;
> +	data2.len = DRBG_STATELEN(drbg);
> +	ret = drbg->core->cipher_fn(drbg, NULL, H, &data1);
> +	if(ret)
> +		goto out;
> +
> +	/* 10.1.1.4 step 5 */
> +	drbg_add_buf(drbg->V, DRBG_STATELEN(drbg),
> +		     H, DRBG_BLOCKLEN(drbg));
> +	drbg_add_buf(drbg->V, DRBG_STATELEN(drbg),
> +		     drbg->C, DRBG_STATELEN(drbg));
> +	drbg_int2byte(req, drbg->reseed_ctr, sizeof(req));
> +	drbg_add_buf(drbg->V, DRBG_STATELEN(drbg), req, 8);
> +
> +out:
> +	DRBG_CLEAR_HASH_BLK(H);
> +	return ret;
> +}
> +
> +static struct drbg_state_ops drbg_hash_ops = {
> +	.process_addtl       = drbg_hash_process_addtl,
> +	.preprocess_extract  = drbg_hash_preprocess_extract,
> +	.postprocess_extract = drbg_hash_postprocess_extract,
> +	.cleanup_extract     = drbg_hash_cleanup_extract,
> +	.newstate_postgen    = drbg_hash_newstate_postgen,
> +	.update_state        = drbg_hash_update_state,
> +};
> +#endif /* CONFIG_CRYPTO_DRBG_HASH */
> +
> +/******************************************************************
> + * Functions common for DRBG implementations
> + ******************************************************************/
> +
> +/*
> + * Set up the pointers to the right DRBG type implementations
> + *
> + * @drbg DRBG handle
> + *
> + * return:
> + * 	0 on success
> + * 	error value otherwise
> + */
> +static inline int drbg_add_callbacks(struct drbg_state *drbg)
> +{
> +#ifdef CONFIG_CRYPTO_DRBG_HMAC
> +	if(drbg->flags & DRBG_HMAC_MASK) {
> +		drbg->d_ops = &drbg_hmac_ops;
> +		return 0;
> +	}
> +#endif /* CONFIG_CRYPTO_DRBG_HMAC */
> +#ifdef CONFIG_CRYPTO_DRBG_HASH
> +	if(drbg->flags & DRBG_HASH_MASK) {
> +		drbg->d_ops = &drbg_hash_ops;
> +		return 0;
> +	}
> +#endif /* CONFIG_CRYPTO_DRBG_HASH */
> +#ifdef CONFIG_CRYPTO_DRBG_CTR
> +	if(drbg->flags & DRBG_CTR_MASK) {
> +		drbg->d_ops = &drbg_ctr_ops;
> +		return 0;
> +	}
> +#endif /* CONFIG_CRYPTO_DRBG_CTR */
> +	return -EOPNOTSUPP;
> +}
> +
> +/*
> + * Seeding or reseeding of the DRBG
> + *
> + * @drbg: DRBG state struct
> + * @pers: personalization / additional information buffer
> + * @perslen: size of personalization / additional information buffer
> + * @reseed: 0 for initial seed process, 1 for reseeding
> + *
> + * return:
> + *	0 on success
> + *	error value otherwise
> + */
> +static int drbg_seed(struct drbg_state *drbg, unsigned char *pers,
> +		     size_t perslen, int reseed)
> +{
> +	int ret = 0;
> +	unsigned char *entropy = NULL;
> +	size_t entropylen = 0;
> +	struct drbg_conc data1, data2;
> +
> +	DRBG_CLEAR_CONC(data1);
> +	DRBG_CLEAR_CONC(data2);
> +
> +	/* 9.1 / 9.2 / 9.3.1 step 3 */
> +	if(perslen > (drbg_max_addtl(drbg)))
> +		return -EINVAL;
> +
> +	/* section 8.6.1 together with section 8.6.3 and 8.6.7 -- consider DRBG
> +	 * seeded only when sufficient seed is provided */
> +	/* Sufficient seed is provided: when we have no derivation function,
> +	 * a nonce is not necessary, if we have a derivation function, a nonce
> +	 * is necessary. A nonce must be at least 1/2 of the security strength
> +	 * of the DRBG in size. Thus, entropy * nonce is 3/2 of the strength.
> +	 *
> +	 * The consideration of a nonce is only applicable during initial
> +	 * seeding.
> +	 */
> +
> +	/* chapter 9: No seed is provided, the DRBG shall get its own seed */
> +	if(drbg->test_data) {
> +		data1.in = drbg->test_data->testentropy;
> +		data1.len = drbg->test_data->testentropylen;
> +	} else {
> +		entropylen = (drbg_sec_strength(drbg->flags) / 8);
> +		if(0 == reseed)
> +		/* make sure we round up strength/2 in
> +		 * case it is not divisible by 2 */
> +			entropylen = ((entropylen + 1) / 2) * 3;
> +
> +		entropy = kzalloc(entropylen, GFP_KERNEL);
> +		if(!entropy)
> +			return -ENOMEM;
> +		get_random_bytes(entropy, entropylen);
> +		data1.in = entropy;
> +		data1.len = entropylen;
> +	}
> +
> +	/* 10.1.1.2 step 1 and 10.1.1.3 step 1 (concatenation of entropy /
> +	 * addtl input) */
> +	if(0 < perslen) {
> +		data1.next = &data2;
> +		data2.in = pers;
> +		data2.len = perslen;
> +	}
> +
> +	ret = drbg->d_ops->update_state(drbg, &data1, reseed);
> +	if(ret)
> +		goto out;
> +
> +	drbg->flags &= ~(DRBG_UNSEEDED);
> +	/* 10.1.1.2 / 10.1.1.3 step 5 */
> +	drbg->reseed_ctr = 1;
> +
> +out:
> +	if (entropy)
> +		kzfree(entropy);
> +	return ret;
> +}
> +
> +/*
> + * Check for reseeding of the DRBG and invoke reseeding if necessary.
> + * This includes the enforcement of the prediction resistance as well
> + * as the reseeding constraint set by the SP800-90A requirement.
> + * 
> + * @drbg: DRBG state struct
> + * @addtl_input: addition input for reseeding
> + * @addtllen: length of additional input
> + *
> + * return:
> + *	0 on success -- implies a successful reseeding of the DRBG handle
> + *	error value otherwise
> + */
> +static int drbg_check_reseed(struct drbg_state *drbg,
> +			     unsigned char **addtl_input, size_t *addtllen)
> +{
> +	int ret = 0;
> +
> +	if((drbg_max_requests(drbg)) < drbg->reseed_ctr)
> +		drbg->flags |= DRBG_UNSEEDED;
> +
> +	/* section 9.3.1 step 6 and 7 */
> +	if(!(drbg->flags & DRBG_PREDICTION_RESIST) &&
> +	   !(drbg->flags & DRBG_UNSEEDED))
> +		return 0;
> +	ret = drbg_seed(drbg, *addtl_input, *addtllen, 1);
> +
> +	/* This is NOT documented, but needed! */
> +	*addtl_input = NULL;
> +	*addtllen = 0;
> +
> +	return ret;
> +}
> +
> +/*
> + * Sanity check of state during drbg_generate() -- we check for:
> + * 	reseeding requirement
> + * 	maximum number of requested bits
> + *
> + * @drbg: DRBG state struct
> + * @strength: requested minimum strength of DRBG
> + * @buflen: size of requested random number
> + *
> + * return:
> + *	0 on success
> + * 	error value otherwise
> + */
> +static inline int drbg_generate_sanity(struct drbg_state *drbg, size_t buflen,
> +				       unsigned char *pers, size_t perslen)
> +{
> +	if(NULL == drbg)
> +		return -EINVAL;
> +	if(NULL == drbg->core)
> +		return -EINVAL;
> +	if(NULL == drbg->V)
> +		return -EINVAL;
> +	if(NULL == drbg->C)
> +		return -EINVAL;
> +	if(NULL == drbg->scratchpad)
> +		return -EINVAL;
> +
> +	/* 9.1 / 9.2 / 9.3.1 step 3 */
> +	if(perslen > (drbg_max_addtl(drbg)))
> +		return -EINVAL;
> +	if(NULL == pers && 0 < perslen)
> +		return -EINVAL;
> +
> +	/* 9.3.1 step 2 -- max_bits is in bits, but buflen is in bytes */
> +	if(buflen > (drbg_max_request_bytes(drbg)))
> +		return -EINVAL;
> +
> +	return 0;
> +}
> +
> +/*
> + * FIPS 140-2 continuous self test
> + * The test is performed on the result of one round of the output
> + * function. Thus, the function implicitly knows the size of the
> + * buffer.
> + *
> + * @drbg DRBG handle
> + * @buf output buffer of random data to be checked
> + *
> + * return:
> + *	true on success
> + * 	false on error
> + */
> +static bool drbg_fips_continuous_test(struct drbg_state *drbg,
> +				     unsigned char *buf)
> +{
> +#ifdef CONFIG_CRYPTO_FIPS
> +	int ret = 0;
> +	/* skip test if we test the overall system */
> +	if(drbg->test_data)
> +		return true;
> +	/* only perform test in FIPS mode */
> +	if(0 == fips_enabled)
> +		return true;
> +	if(!drbg->prev) {
> +		drbg->prev = kzalloc(DRBG_BLOCKLEN(drbg), GFP_KERNEL);
> +		if(!drbg->prev)
> +			return -ENOMEM;
> +		/* Priming of FIPS test */
> +		memcpy(drbg->prev, buf, DRBG_BLOCKLEN(drbg));
> +		/* return false due to priming, i.e. another round is needed */
> +		return false;
> +	}
> +	ret = memcmp(drbg->prev, buf, DRBG_BLOCKLEN(drbg));
> +	memcpy(drbg->prev, buf, DRBG_BLOCKLEN(drbg));
> +	/* invert the memcmp result, because the test shall pass when the
> +	 * two compared values do not match */
> +	if(ret)
> +		return true;
> +	else
> +		return false;
> +#else
> +	return true;
> +#endif /* CONFIG_CRYPTO_FIPS */
> +}
> +
> +/*
> + * Heavy lifting function of generating random numbers by generating
> + * blockwise output via cipher and ensuring that the last block is truncated
> + * to the proper length.
> + *
> + * @drbg DRBG handle
> + * @buf output buffer of random data
> + * @buflen length of output buffer
> + *
> + * return: generated bytes
> + */
> +static unsigned int drbg_extract_bytes(struct drbg_state *drbg,
> +				       unsigned char *buf,
> +				       unsigned int buflen)
> +{
> +	int ret = 0;
> +	/* 10.1.1.4 step 1 */
> +	unsigned int len = 0;
> +	unsigned char *src = NULL;
> +	unsigned char *dst = NULL;
> +	short length = 0;
> +	struct drbg_conc data;
> +
> +	DRBG_CLEAR_CONC(data);
> +
> +	/* set up the source buffers and destination buffers as needed for
> +	 * the DRBG type -- the source buffer is fed into the cipher operation
> +	 * and the destination buffer will hold the result of the cipher
> +	 * operation */
> +	ret = drbg->d_ops->preprocess_extract(drbg, &src, &dst, &length);
> +	if(ret)
> +		return 0;
> +	data.in = src;
> +	data.len = length;
> +
> +	/* potential integer overflow is covered by drbg_generate_sanity which
> +	 * ensures that buflen cannot overflow a signed int */
> +	while(len < buflen) {
> +		unsigned int outlen = 0;
> +		/* 10.1.1.4 step hashgen 4.1, 10.1.2.5 step 4.1,
> +		 * 10.2.1.5.2 step 4.2 */
> +		ret = drbg->core->cipher_fn(drbg, drbg->C, dst, &data);
> +		if(ret)
> +			goto out;
> +		outlen = (DRBG_BLOCKLEN(drbg) < (buflen - len)) ?
> +			  DRBG_BLOCKLEN(drbg) : (buflen - len);
> +		if(!drbg_fips_continuous_test(drbg, dst)) {
> +			/* Continuous test failed or is just primed -- generate
> +			 * next round without copying the generated value out
> +			 * to the caller -- potential for a deadlock, but
> +			 * this error cannot mathematically occur. If it
> +			 * occurs, the integrity of the entire kernel is
> +			 * lost. */
> +			drbg->d_ops->postprocess_extract(drbg, src, dst,
> +							 (len < buflen));
> +			continue;
> +		}
> +		/* 10.1.1.4 step hashgen 4.2, 10.1.2.5 step 4.2,
> +		 * 10.2.1.5.2 step 4.3 */
> +		memcpy(buf + len, dst, outlen);
> +		len += outlen;
> +		/* Advance the buffers, if needed by the DRBG type */
> +		drbg->d_ops->postprocess_extract(drbg, src, dst,
> +						 (len < buflen));
> +	}
> +
> +out:
> +	/* Allow DRBG type implementations to cleanup any temporary buffers
> +	 * set up when defining source and destination buffers
> +	 */
> +	drbg->d_ops->cleanup_extract(drbg, &src, &dst);
> +	return len;
> +}
> +
> +/*
> + * Process request to generate random numbers. This function ensures
> + * that the additional information / personalization string is processed
> + * before bytes are generated. Also, this function ensures that the DRBG
> + * state is updated after random number generation.
> + *
> + * @drbg DRBG handle
> + * @buf output buffer of random data
> + * @buflen length of output buffer
> + * @addtl_input Additional input / personalization string buffer
> + * @addtllen Length of additional input buffer
> + *
> + * return: generated bytes
> + */
> +static unsigned int drbg_generate_bytes(struct drbg_state *drbg,
> +					unsigned char *buf, unsigned int buflen,
> +					unsigned char *addtl_input,
> +					size_t addtllen)
> +{
> +	unsigned int len = 0;
> +
> +	/* 10.1.1.4 step 2, 10.1.2.5 step 2, 10.2.1.5.2 step 2 */
> +	if(drbg->d_ops->process_addtl(drbg, addtl_input, addtllen))
> +		return 0;
> +	/* 10.1.1.4 step 3, 10.1.2.5 step 3, 10.2.1.5.2 step 3 */
> +	len = drbg_extract_bytes(drbg, buf, buflen);
> +	
> +	/* 10.1.1.4 step 4 and following, 10.1.2.5 step 6, 10.2.1.5.2 step 6 */
> +	if(drbg->d_ops->newstate_postgen(drbg, addtl_input, addtllen))
> +		return 0;
> +	return len;
> +}
> +
> +/*
> + * Check for programming errors: ensure that stack variable size is
> + * sufficient for ciphers.
> + *
> + * @flags flags specifying the core cipher type
> + * @core selected core
> + *
> + * return:
> + * 	true if sanity check passed
> + * 	false if sanity check failed
> + */
> +static inline bool drbg_check_progamming_sanity(drbg_flag_t flags,
> +					 const struct drbg_core *core)
> +{
> +	size_t size = 0;
> +	if(flags & DRBG_CTR_MASK)
> +		size = DRBG_CTR_BLK;
> +	else if (flags & DRBG_HASH_MASK)
> +		size = DRBG_HASH_BLK;
> +	else if (flags & DRBG_HMAC_MASK)
> +		size = DRBG_HMAC_BLK;
> +	return (size >= core->statelen);
> +}
> +
> +/*
> + * Find the right cipher callback data structure that matches the
> + * the requested cipher type. The code returns the first match in case caller
> + * made the error to request multiple ciphers
> + *
> + * @flags Flags handed in by caller during instantiation request
> + *
> + * return:
> + * 	pointer to core on success
> + * 	NULL on error
> + */
> +static const inline struct drbg_core *drbg_find_core(drbg_flag_t flags)
> +{
> +	drbg_flag_t req_cipher = (flags & DRBG_CIPHER_MASK);
> +	int i = 0;
> +
> +	for(i = 0; ARRAY_SIZE(cores) > i; i++) {
> +		if(req_cipher & cores[i].flags) {
> +			if(drbg_check_progamming_sanity(req_cipher, &cores[i]))
> +				return &cores[i];
> +			return NULL;
> +		}
> +	}
> +	return NULL;
> +}
> +
> +/*************************************************************************
> + * DRBG interface functions
> + *************************************************************************/
> +
> +/*
> + * DRBG instantiation function as required by SP800-90A - this function
> + * sets up the DRBG handle, performs the initial seeding and all sanity
> + * checks required by SP800-90A
> + *
> + * @drbg memory of state -- if NULL, new memory is allocated
> + * @pers Personalization string that is mixed into state, may be NULL -- note
> + * 	 the entropy is pulled by the DRBG internally unconditionally
> + * 	 as defined in SP800-90A. The additional input is mixed into
> + * 	 the state in addition to the pulled entropy.
> + * @perslen Length of personalization string buffer, shall be 0 when buffer
> + *	    is NULL
> + * @flags Flags defining the requested DRBG type and cipher type. The flags
> + * 	  are defined in drbg.h and may be XORed. Beware, if you XOR multiple
> + * 	  cipher types together, the code picks the core on a first come first
> + * 	  serve basis as it iterates through the available cipher cores and
> + * 	  uses the one with the first match. The minimum required flags are:
> + * 		cipher type flag
> + *
> + * return
> + * 	0 on success
> + * 	error value otherwise
> + */
> +
> +static int drbg_instantiate(struct drbg_state *drbg,
> +			    unsigned char *pers, size_t perslen,
> +			    drbg_flag_t flags)
> +{
> +	int ret = -ENOMEM;
> +	const struct drbg_core *core = NULL;
> +
> +	core = drbg_find_core(flags);
> +	if(NULL == core)
> +		return -EINVAL;
> +
> +	/* 9.1 step 1 is implicit with the selected DRBG type -- see
> +	 * drbg_sec_strength() */
> +
> +	/* 9.1 step 2 is implicit as caller can select prediction resistance
> +	 * and the flag is copied into drbg->flags --
> +	 * all DRBG types support prediction resistance */
> +
> +	/* 9.1 step 4 is implicit in  drbg_sec_strength */
> +
> +	/* no allocation of drbg as this is done by the kernel crypto API */
> +	drbg->V = kzalloc(core->statelen, GFP_KERNEL);
> +	if(!drbg->V)
> +		goto err;
> +	drbg->C = kzalloc(core->statelen, GFP_KERNEL);
> +	if(!drbg->C)
> +		goto err;
> +
> +	/* the Hash DRBG needs full buffer, CTR needs only blocklen_bytes and
> +	 * HMAC does not need buffer at all */
> +	drbg->scratchpad = kzalloc(core->statelen + core->blocklen_bytes,
> +				   GFP_KERNEL);
> +	if(!drbg->scratchpad)
> +		goto err;
> +
> +	spin_lock_init(&drbg->drbg_lock);
> +
> +	drbg->flags = flags;
> +	drbg->flags |= DRBG_UNSEEDED;
> +	drbg->core = core;
> +
> +	if(core->init_lib)
> +		if(core->init_lib(drbg))
> +			return -EFAULT;
> +
> +	ret = drbg_add_callbacks(drbg);
> +	if(ret)
> +		goto err;
> +
> +	/* 9.1 step 6 through 11 */
> +	ret = drbg_seed(drbg, pers, perslen, 0);
> +	if(ret)
> +		goto err;
> +
> +	return 0;
> +
> +err:
> +	if(drbg->C)
> +		kzfree(drbg->C);
> +	drbg->C = NULL;
> +	if(drbg->V)
> +		kzfree(drbg->V);
> +	drbg->V = NULL;
> +	if(drbg->scratchpad)
> +		kzfree(drbg->scratchpad);
> +	drbg->scratchpad = NULL;
> +	return ret;
> +}
> +
> +/*
> + * DRBG uninstantiate function as required by SP800-90A - this function
> + * frees all buffers and the DRBG handle
> + *
> + * @drbg DRBG state handle
> + * @free_state free the DRBG state handle in addition to zeroization
> + *
> + * return
> + * 	0 on success
> + */
> +static int drbg_uninstantiate(struct drbg_state *drbg)
> +{
> +	/* ensure that other threads have their chance to complete their work */
> +	spin_lock_bh(&drbg->drbg_lock);
> +	if(drbg->core->fini_lib)
> +		drbg->core->fini_lib(drbg);
> +	if(drbg->V)
> +		kzfree(drbg->V);
> +	drbg->V = NULL;
> +	if(drbg->C)
> +		kzfree(drbg->C);
> +	drbg->C = NULL;
> +	if(drbg->scratchpad)
> +		kzfree(drbg->scratchpad);
> +	drbg->scratchpad = NULL;
> +#ifdef CONFIG_CRYPTO_FIPS
> +	if(drbg->prev)
> +		kzfree(drbg->prev);
> +	drbg->prev = NULL;
> +#endif
> +	/* no scrubbing of test_data -- this shall survive an uninstantiate */
> +	spin_unlock_bh(&drbg->drbg_lock);
> +	/* no freeing of drbg as this is done by the kernel crypto API */
> +	return 0;
> +}
> +
> +/*
> + * DRBG generate function as required by SP800-90A - this function
> + * generates random numbers
> + *
> + * @drbg DRBG state handle
> + * @buf Buffer where to store the random numbers -- the buffer must already
> + *      be pre-allocated by caller
> + * @buflen Length of output buffer - this value defines the number of random
> + * 	   bytes pulled from DRBG
> + * @addtl_input Additional input that is mixed into state, may be NULL -- note
> + * 		the entropy is pulled by the DRBG internally unconditionally
> + * 		as defined in SP800-90A. The additional input is mixed into
> + * 		the state in addition to the pulled entropy.
> + * @addtllen Length of additional input buffer, shall be 0 when buffer is NULL
> + *
> + * return: generated number of bytes
> + */
> +static unsigned int drbg_generate(struct drbg_state *drbg,
> +				  unsigned char *buf, unsigned int buflen,
> +				  unsigned char *addtl_input, size_t addtllen)
> +{
> +	unsigned int len = 0;
> +
> +	if(0 == buflen)
> +		return 0;
> +
> +	spin_lock_bh(&drbg->drbg_lock);
> +	if(drbg_generate_sanity(drbg, buflen, addtl_input, addtllen))
> +		goto out;
> +
> +	if(drbg_check_reseed(drbg, &addtl_input, &addtllen))
> +		goto out;
> +
> +	len = drbg_generate_bytes(drbg, buf, buflen, addtl_input, addtllen);
> +
> +	/* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */
> +	drbg->reseed_ctr++;
> +
> +out:
> +	spin_unlock_bh(&drbg->drbg_lock);
> +	return len;
> +}
> +
> +/*
> + * DRBG reseed function as required by SP800-90A
> + *
> + * @drbg DRBG state handle
> + * @addtl_input Additional input that is mixed into state, may be NULL -- note
> + * 		the entropy is pulled by the DRBG internally unconditionally
> + * 		as defined in SP800-90A. The additional input is mixed into
> + * 		the state in addition to the pulled entropy.
> + * @addtllen Length of additional input buffer, shall be 0 when buffer is NULL
> + *
> + * return
> + * 	0 on success
> + * 	error value otherwise
> + */
> +/* The kernel crypto API does not implement a reseeding function API call.
> + * This function should be enabled once a reseeding API call is implemented.
> + */
> +#if 0
> +static int drbg_reseed(struct drbg_state *drbg, unsigned char *addtl_input,
> +		       size_t addtllen)
> +{
> +	int ret = 0;
> +	spin_lock_bh(&drbg->drbg_lock);
> +	ret = drbg_seed(drbg, addtl_input, addtllen, 1);
> +	spin_unlock_bh(&drbg->drbg_lock);
> +	return ret;
> +}
> +#endif
> +
> +/*
> + * Helper function for setting the test data in the DRBG
> + *
> + * @drbg DRBG state handle
> + * @test_data test data to sets
> + */
> +static inline void drbg_set_testdata(struct drbg_state *drbg,
> +			      struct drbg_test_data *test_data)
> +{
> +	if(!test_data)
> +		return;
> +	spin_lock_bh(&drbg->drbg_lock);
> +	drbg->test_data = test_data;
> +	spin_unlock_bh(&drbg->drbg_lock);
> +}
> +
> +/***************************************************************
> + * Kernel crypto APi cipher invocations requested by DRBG
> + ***************************************************************/
> +
> +#if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
> +static int drbg_init_hash_kernel(struct drbg_state *drbg)
> +{
> +	int ret = 0;
> +	struct shash_desc *shash;
> +	int size;
> +	struct crypto_shash *tfm;
> +
> +	/* allocate synchronous hash */
> +	tfm = crypto_alloc_shash(drbg->core->backend_cra_name, 0, 0);
> +	if (IS_ERR(tfm)) {
> +		printk("drbg: could not allocate digest TFM handle\n");
> +		return -EFAULT;
> +	}
> +
> +	size = sizeof(struct shash_desc);
> +	shash = kzalloc(size, GFP_KERNEL);
> +	if (!shash) {
> +		crypto_free_shash(tfm);
> +		return -ENOMEM;
> +	}
> +	shash->tfm = tfm;
> +	shash->flags = 0x0;
> +	drbg->priv_data = shash;
> +
> +	return ret;
> +}
> +
> +static int drbg_fini_hash_kernel(struct drbg_state *drbg)
> +{
> +	struct shash_desc *shash = (struct shash_desc *)drbg->priv_data;
> +	if(shash) {
> +		crypto_free_shash(shash->tfm);
> +		kzfree(shash);
> +	}
> +	drbg->priv_data = NULL;
> +	return 0;
> +}
> +
> +static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *key,
> +			   unsigned char *outval, struct drbg_conc *in)
> +{
> +	struct shash_desc *shash = (struct shash_desc *)drbg->priv_data;
> +	crypto_shash_init(shash);
> +	for(; NULL != in; in = in->next)
> +		crypto_shash_update(shash, in->in, in->len);
> +	return crypto_shash_final(shash, outval);
> +}
> +#endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
> +
> +#ifdef CONFIG_CRYPTO_DRBG_HMAC
> +static int drbg_kcapi_hmac(struct drbg_state *drbg, unsigned char *key,
> +			   unsigned char *outval, struct drbg_conc *in)
> +{
> +	int ret = 0;
> +	struct shash_desc *shash = (struct shash_desc *)drbg->priv_data;
> +	ret = crypto_shash_setkey(shash->tfm, key, DRBG_STATELEN(drbg));
> +	if(ret)
> +		return ret;
> +	return drbg_kcapi_hash(drbg, key, outval, in);
> +}
> +#endif /* CONFIG_CRYPTO_DRBG_HMAC */
> +
> +#ifdef CONFIG_CRYPTO_DRBG_CTR
> +static int drbg_init_sym_kernel(struct drbg_state *drbg)
> +{
> +	int ret = 0;
> +	struct blkcipher_desc *desc;
> +	struct crypto_blkcipher *blkcipher;
> +
> +	/* allocate synchronous cipher */
> +	blkcipher = crypto_alloc_blkcipher(drbg->core->backend_cra_name, 0, 0);
> +	if(IS_ERR(blkcipher)) {
> +		printk("drbg: could not allocate cipher TFM handle\n");
> +		return -EFAULT;
> +	}
> +
> +	desc = kzalloc(sizeof(struct blkcipher_desc), GFP_KERNEL);
> +	if (!desc) {
> +		crypto_free_blkcipher(blkcipher);
> +		return -ENOMEM;
> +	}
> +	desc->tfm = blkcipher;
> +        desc->flags = 0;
> +	drbg->priv_data = desc;
> +
> +	return ret;
> +}
> +
> +static int drbg_fini_sym_kernel(struct drbg_state *drbg)
> +{
> +	struct blkcipher_desc *desc =
> +		(struct blkcipher_desc *)drbg->priv_data;
> +	if(desc) {
> +		crypto_free_blkcipher(desc->tfm);
> +		kzfree(desc);
> +	}
> +	drbg->priv_data = NULL;
> +	return 0;
> +}
> +
> +static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *key,
> +			  unsigned char *outval, struct drbg_conc *in)
> +{
> +	int ret = 0;
> +	struct scatterlist sg_in, sg_out;
> +	struct blkcipher_desc *desc =
> +		(struct blkcipher_desc *)drbg->priv_data;
> +
> +	if(crypto_blkcipher_setkey(desc->tfm, key, (DRBG_KEYLEN(drbg))))
> +		return -EFAULT;
> +	/* in is only component */
> +	sg_init_one(&sg_in, in->in, in->len);
> +	sg_init_one(&sg_out, outval, DRBG_BLOCKLEN(drbg));
> +	ret = crypto_blkcipher_encrypt(desc, &sg_out, &sg_in, in->len);
> +
> +	return ret;
> +}
> +#endif /* CONFIG_CRYPTO_DRBG_CTR */
> +
> +/***************************************************************
> + * Kernel crypto API interface to register DRBG
> + ***************************************************************/
> +
> +/*
> + * Look up the DRBG flags by given kernel crypto API cra_name
> + * The code uses the cores definition to do this
> + * 
> + * @cra_name kernel crypto API cra_name
> + * 
> + * return: flags
> + */
> +static drbg_flag_t drbg_convert_tfm_flags(const char *cra_name)
> +{
> +	int i = 0;
> +	size_t start = 0;
> +	int len = 0;
> +	drbg_flag_t pr_flag = DRBG_PREDICTION_RESIST;
> +	
> +	/* disassemble the names */
> +	if(0 == memcmp(cra_name, "drbg(nopr(", 10)) {
> +		start = 10;
> +		pr_flag = 0;
> +	} else if (0 == memcmp(cra_name, "drbg(pr(", 8)) {
> +		start = 8;
> +	} else
> +		return 0;
> +	
> +	/* remove the first part and the closing parenthesis */
> +	len = strlen(cra_name) - start - 2;
> +	
> +	for(i = 0; ARRAY_SIZE(cores) > i; i++) {
> +		if(0 == memcmp(cra_name + start, cores[i].cra_name, len))
> +			/* add the prediction resistance flag, if drbg(pr(()))
> +			 * is selected */
> +			return (cores[i].flags | pr_flag);
> +	}
> +	return 0;
> +}
> +
> +/*
> + * Initialize one DRBG invoked by the kernel crypto API
> + * 
> + * Function uses the kernel crypto API cra_name to look up
> + * the flags to instantiate the DRBG
> + */
> +static int drbg_kcapi_init(struct crypto_tfm *tfm)
> +{
> +	struct drbg_state *drbg = crypto_tfm_ctx(tfm);
> +	drbg_flag_t flags = 0;
> +	
> +	flags = drbg_convert_tfm_flags(crypto_tfm_alg_name(tfm));
> +	/* when personalization string is needed, the caller must call reset
> +	 * and provide the personalization string as seed information */
> +	return drbg_instantiate(drbg, NULL, 0, flags);
> +}
> +
> +static void drbg_kcapi_cleanup(struct crypto_tfm *tfm)
> +{
> +	drbg_uninstantiate(crypto_tfm_ctx(tfm));
> +}
> +
> +/*
> + * Generate random numbers:
> + * The API of the kernel crypto API is extended as follows:
> + * 
> + * If dlen is larger than zero, rdata is interpreted as the output buffer
> + * where random data is to be stored.
> + * 
> + * If dlen is zero, rdata is interpreted as a pointer to a struct drbg_gen
> + * which holds the additional information string that is used for the
> + * DRBG generation process. The output buffer that is to be used to store
> + * data is also pointed to by struct drbg_gen.
> + * 
> + */
> +static int drbg_kcapi_random(struct crypto_rng *tfm, u8 *rdata,
> +			     unsigned int dlen)
> +{
> +	struct drbg_state *drbg = crypto_rng_ctx(tfm);
> +	if(0 < dlen) {
> +		return drbg_generate(drbg, rdata, dlen,
> +				     NULL, 0);
> +	} else {
> +		struct drbg_gen *data = (struct drbg_gen *)rdata;
> +		drbg_set_testdata(drbg, data->test_data);
> +		return drbg_generate(drbg, data->outbuf, data->outlen,
> +				     data->addtl_input, data->addtllen);
> +	}
> +}
> +
> +static int drbg_kcapi_reset(struct crypto_rng *tfm, u8 *seed, unsigned int slen)
> +{
> +	struct drbg_state *drbg = crypto_rng_ctx(tfm);
> +	struct crypto_tfm *tfm_base = crypto_rng_tfm(tfm);
> +	drbg_flag_t flags = 0;
> +
> +	drbg_uninstantiate(drbg);
> +	flags = drbg_convert_tfm_flags(crypto_tfm_alg_name(tfm_base));
> +	if(0 < slen) {
> +		return drbg_instantiate(drbg, seed, slen, flags);
> +	} else {
> +		struct drbg_gen *data = (struct drbg_gen *)seed;
> +		drbg_set_testdata(drbg, data->test_data);
> +		return drbg_instantiate(drbg, data->addtl_input, data->addtllen,
> +					flags);
> +	}
> +}
> +
> +/***************************************************************
> + * Kernel module: code to load the module
> + ***************************************************************/
> +
> +static struct crypto_alg drbg_algs[22];
> +
> +/* 
> + * Fill the array drbg_algs used to register the different DRBGs
> + * with the kernel crypto API. To fill the array, the information
> + * from cores[] is used.
> + */
> +static void __init drbg_fill_array(unsigned long i, unsigned long j, int pr)
> +{
> +	int pos = 0;
> +
> +	memset(&drbg_algs[i], 0, sizeof(struct crypto_alg));
> +	if(pr) {
> +		memcpy(drbg_algs[i].cra_name, "drbg(pr(", 8);
> +		memcpy(drbg_algs[i].cra_driver_name, "drbg_pr_", 8);
> +		pos = 8;
> +	} else {
> +		memcpy(drbg_algs[i].cra_name, "drbg(nopr(", 10);
> +		memcpy(drbg_algs[i].cra_driver_name, "drbg_nopr_", 10);
> +		pos = 10;
> +	}
> +	memcpy(drbg_algs[i].cra_name + pos, cores[j].cra_name,
> +	       strlen(cores[j].cra_name));
> +	memcpy(drbg_algs[i].cra_name + pos + strlen(cores[j].cra_name), "))", 2);
> +	memcpy(drbg_algs[i].cra_driver_name + pos,
> +	       cores[j].cra_driver_name, strlen(cores[j].cra_driver_name));
> +	drbg_algs[i].cra_priority	= 100;
> +	drbg_algs[i].cra_flags	= CRYPTO_ALG_TYPE_RNG;
> +	drbg_algs[i].cra_ctxsize= sizeof(struct drbg_state);
> +	drbg_algs[i].cra_type	= &crypto_rng_type;
> +	drbg_algs[i].cra_module	= THIS_MODULE;
> +	drbg_algs[i].cra_init	= drbg_kcapi_init;
> +	drbg_algs[i].cra_exit	= drbg_kcapi_cleanup;
> +	drbg_algs[i].cra_u.rng.rng_make_random	= drbg_kcapi_random;
> +	drbg_algs[i].cra_u.rng.rng_reset	= drbg_kcapi_reset;
> +	drbg_algs[i].cra_u.rng.seedsize		= 0;
> +}
> +
> +static void __init drbg_create_algs(void)
> +{
> +	unsigned int i = 0; /* pointer to drbg_algs */
> +	unsigned int j = 0; /* pointer to cores */
> +	
> +	if(ARRAY_SIZE(cores) * 2 > ARRAY_SIZE(drbg_algs))
> +		printk("drbg: Not all available DRBGs registered (slots needed:"
> +		       "%lu, slots available: %lu)\n",
> +		       ARRAY_SIZE(cores) * 2, ARRAY_SIZE(drbg_algs));
> +
> +	/* each DRBG definition can be used with PR and without PR, thus
> +	 * we instantiate each DRBG in cores[] twice */
> +	for(j = 0; ARRAY_SIZE(cores) > j; j++) {
> +		drbg_fill_array(i, j, 1);
> +		i++;
> +		drbg_fill_array(i, j, 0);
> +		i++;
> +	}
> +}
> +
> +static int __init drbg_init(void)
> +{
> +	drbg_create_algs();
> +	return crypto_register_algs(drbg_algs, (ARRAY_SIZE(cores) * 2));
> +}
> +
> +void __exit drbg_exit(void)
> +{
> +        crypto_unregister_algs(drbg_algs, (ARRAY_SIZE(cores) * 2));
> +}
> +
> +module_init(drbg_init);
> +module_exit(drbg_exit);
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Stephan Mueller <smueller@...onox.de>");
> +MODULE_DESCRIPTION("NIST SP800-90A Determinist Random Bit Generator (DRBG) using following cores:"
> +#ifdef CONFIG_CRYPTO_DRBG_HMAC
> +"HMAC "
> +#endif
> +#ifdef CONFIG_CRYPTO_DRBG_HASH
> +"Hash "
> +#endif
> +#ifdef CONFIG_CRYPTO_DRBG_CTR
> +"CTR"
> +#endif
> +);
> +
> -- 
> 1.8.5.3
> 

Stephan,

here are my findings for this patch:

* CodingStyle: 
  - You have to observe what goes written in Documentation/CodingStyle 
    special emphasis on, but not only restricted to, function-versus-keyword 
    space usage.

* scheduling while atomic BUGs: 
  - suspicious spinlock protection around callsites to crypto api callbacks:
    Unless you can guarantee those callbacks do not conditionally call the 
    scheduler, you'll hit racy bugs on the wild world for sure;
  - drbg_fips_continous_test(): you _cannot_ perform non-atomic
    allocations within an atomic section, this is a real BUG and it will bite
    you sooner or later;

* spin_lock_bh abusive usage @ drbg_generate():
  - you hold the spinlock (with disabled IRQs) for a rather too big
    critical section, even across several function calls, and this
    should be avoided at all costs. You really should refactor you
    spinlock crit sects to only grab the lock for a couple few lines
    of _machine_ code.


Overall impressions: your code is quite difficult to follow (and it will
be potentially hard to maintain and debug, if merged as it sits) due to
that indirection model chosen to split the implementation of DRBGs
across several tiny functions. Doing that much of callbacks is very 
costly and it's not optimal for kernel code, as it causes unnecessary 
register thrashing. 
By reading the specs, one can conclude you could only use two callbacks 
(one for the generate function and another for the (re)seed function)
and get the rest of particular stuff for each drbg implementation all inlined.

Regards,
-- Rafael
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