/*
   * 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@chronox.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];
   * struct drbg_string pers;
   * char personalization[11] = "some-string";
   *
   * drbg_string_fill(&pers, personalization, strlen(personalization));
   * 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_string[11] = "some-string";
   * string drbg_string addtl;
   *
   * drbg_string_fill(&addtl, addtl_string, strlen(addtl_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);
   * crypto_free_rng(drng);
   *
   *
   * Usage with personalization and additional information strings
   * -------------------------------------------------------------
   * Just mix both scenarios above.
   */
  
  #include <crypto/drbg.h>

  #include <crypto/internal/cipher.h>

  #include <linux/kernel.h>

  /***************************************************************
   * Backend cipher definitions available to DRBG
   ***************************************************************/
  
  /*
   * The order of the DRBG definitions here matter: every DRBG is registered
   * as stdrng. Each DRBG receives an increasing cra_priority values the later
   * they are defined in this array (see drbg_fill_array).
   *
   * HMAC DRBGs are favored over Hash DRBGs over CTR DRBGs, and
   * the SHA256 / AES 256 over other ciphers. Thus, the favored
   * DRBGs are the latest entries in this array.
   */
  static const struct drbg_core drbg_cores[] = {
  #ifdef CONFIG_CRYPTO_DRBG_CTR
  	{
  		.flags = DRBG_CTR | DRBG_STRENGTH128,
  		.statelen = 32, /* 256 bits as defined in 10.2.1 */

  		.blocklen_bytes = 16,
  		.cra_name = "ctr_aes128",

  		.backend_cra_name = "aes",

  	}, {
  		.flags = DRBG_CTR | DRBG_STRENGTH192,
  		.statelen = 40, /* 320 bits as defined in 10.2.1 */

  		.blocklen_bytes = 16,
  		.cra_name = "ctr_aes192",

  		.backend_cra_name = "aes",

  	}, {
  		.flags = DRBG_CTR | DRBG_STRENGTH256,
  		.statelen = 48, /* 384 bits as defined in 10.2.1 */

  		.blocklen_bytes = 16,
  		.cra_name = "ctr_aes256",

  		.backend_cra_name = "aes",

  	},
  #endif /* CONFIG_CRYPTO_DRBG_CTR */
  #ifdef CONFIG_CRYPTO_DRBG_HASH
  	{
  		.flags = DRBG_HASH | DRBG_STRENGTH128,
  		.statelen = 55, /* 440 bits */

  		.blocklen_bytes = 20,
  		.cra_name = "sha1",
  		.backend_cra_name = "sha1",
  	}, {
  		.flags = DRBG_HASH | DRBG_STRENGTH256,
  		.statelen = 111, /* 888 bits */

  		.blocklen_bytes = 48,
  		.cra_name = "sha384",
  		.backend_cra_name = "sha384",
  	}, {
  		.flags = DRBG_HASH | DRBG_STRENGTH256,
  		.statelen = 111, /* 888 bits */

  		.blocklen_bytes = 64,
  		.cra_name = "sha512",
  		.backend_cra_name = "sha512",
  	}, {
  		.flags = DRBG_HASH | DRBG_STRENGTH256,
  		.statelen = 55, /* 440 bits */

  		.blocklen_bytes = 32,
  		.cra_name = "sha256",
  		.backend_cra_name = "sha256",
  	},
  #endif /* CONFIG_CRYPTO_DRBG_HASH */
  #ifdef CONFIG_CRYPTO_DRBG_HMAC
  	{

  		.flags = DRBG_HMAC | DRBG_STRENGTH128,

  		.statelen = 20, /* block length of cipher */

  		.blocklen_bytes = 20,
  		.cra_name = "hmac_sha1",
  		.backend_cra_name = "hmac(sha1)",
  	}, {
  		.flags = DRBG_HMAC | DRBG_STRENGTH256,
  		.statelen = 48, /* block length of cipher */

  		.blocklen_bytes = 48,
  		.cra_name = "hmac_sha384",
  		.backend_cra_name = "hmac(sha384)",
  	}, {
  		.flags = DRBG_HMAC | DRBG_STRENGTH256,

  		.statelen = 32, /* block length of cipher */

  		.blocklen_bytes = 32,
  		.cra_name = "hmac_sha256",
  		.backend_cra_name = "hmac(sha256)",

  	}, {
  		.flags = DRBG_HMAC | DRBG_STRENGTH256,
  		.statelen = 64, /* block length of cipher */
  		.blocklen_bytes = 64,
  		.cra_name = "hmac_sha512",
  		.backend_cra_name = "hmac(sha512)",

  	},
  #endif /* CONFIG_CRYPTO_DRBG_HMAC */
  };

  static int drbg_uninstantiate(struct drbg_state *drbg);

  /******************************************************************
   * Generic helper functions
   ******************************************************************/
  
  /*
   * Return strength of DRBG according to SP800-90A section 8.4
   *
   * @flags DRBG flags reference
   *
   * Return: normalized strength in *bytes* value or 32 as default
   *	   to counter programming errors
   */
  static inline unsigned short drbg_sec_strength(drbg_flag_t flags)
  {
  	switch (flags & DRBG_STRENGTH_MASK) {
  	case DRBG_STRENGTH128:
  		return 16;
  	case DRBG_STRENGTH192:
  		return 24;
  	case DRBG_STRENGTH256:
  		return 32;
  	default:
  		return 32;
  	}
  }
  
  /*

   * FIPS 140-2 continuous self test for the noise source
   * The test is performed on the noise source input data. Thus, the function
   * implicitly knows the size of the buffer to be equal to the security
   * strength.
   *
   * Note, this function disregards the nonce trailing the entropy data during
   * initial seeding.
   *
   * drbg->drbg_mutex must have been taken.
   *
   * @drbg DRBG handle
   * @entropy buffer of seed data to be checked
   *
   * return:
   *	0 on success
   *	-EAGAIN on when the CTRNG is not yet primed
   *	< 0 on error
   */
  static int drbg_fips_continuous_test(struct drbg_state *drbg,
  				     const unsigned char *entropy)
  {
  	unsigned short entropylen = drbg_sec_strength(drbg->core->flags);
  	int ret = 0;
  
  	if (!IS_ENABLED(CONFIG_CRYPTO_FIPS))
  		return 0;
  
  	/* skip test if we test the overall system */
  	if (list_empty(&drbg->test_data.list))
  		return 0;
  	/* only perform test in FIPS mode */
  	if (!fips_enabled)
  		return 0;
  
  	if (!drbg->fips_primed) {
  		/* Priming of FIPS test */
  		memcpy(drbg->prev, entropy, entropylen);
  		drbg->fips_primed = true;
  		/* priming: another round is needed */
  		return -EAGAIN;
  	}
  	ret = memcmp(drbg->prev, entropy, entropylen);
  	if (!ret)
  		panic("DRBG continuous self test failed
  ");
  	memcpy(drbg->prev, entropy, entropylen);
  
  	/* the test shall pass when the two values are not equal */
  	return 0;
  }
  
  /*

   * Convert an integer into a byte representation of this integer.
   * The byte representation is big-endian
   *

   * @val value to be converted

   * @buf buffer holding the converted integer -- caller must ensure that
   *      buffer size is at least 32 bit

   */
  #if (defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR))

  static inline void drbg_cpu_to_be32(__u32 val, unsigned char *buf)

  {

  	struct s {

  		__be32 conv;

  	};
  	struct s *conversion = (struct s *) buf;

  	conversion->conv = cpu_to_be32(val);

  }

  #endif /* defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR) */
  
  /******************************************************************
   * CTR DRBG callback functions
   ******************************************************************/
  
  #ifdef CONFIG_CRYPTO_DRBG_CTR

  #define CRYPTO_DRBG_CTR_STRING "CTR "

  MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes256");
  MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes256");
  MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes192");
  MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes192");
  MODULE_ALIAS_CRYPTO("drbg_pr_ctr_aes128");
  MODULE_ALIAS_CRYPTO("drbg_nopr_ctr_aes128");

  static void drbg_kcapi_symsetkey(struct drbg_state *drbg,
  				 const unsigned char *key);
  static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
  			  const struct drbg_string *in);

  static int drbg_init_sym_kernel(struct drbg_state *drbg);
  static int drbg_fini_sym_kernel(struct drbg_state *drbg);

  static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
  			      u8 *inbuf, u32 inbuflen,
  			      u8 *outbuf, u32 outlen);

  #define DRBG_OUTSCRATCHLEN 256

  
  /* BCC function for CTR DRBG as defined in 10.4.3 */
  static int drbg_ctr_bcc(struct drbg_state *drbg,
  			unsigned char *out, const unsigned char *key,

  			struct list_head *in)

  {

  	int ret = 0;
  	struct drbg_string *curr = NULL;

  	struct drbg_string data;

  	short cnt = 0;

  
  	drbg_string_fill(&data, out, drbg_blocklen(drbg));

  	/* 10.4.3 step 2 / 4 */

  	drbg_kcapi_symsetkey(drbg, key);

  	list_for_each_entry(curr, in, list) {
  		const unsigned char *pos = curr->buf;
  		size_t len = curr->len;

  		/* 10.4.3 step 4.1 */

  		while (len) {
  			/* 10.4.3 step 4.2 */
  			if (drbg_blocklen(drbg) == cnt) {
  				cnt = 0;

  				ret = drbg_kcapi_sym(drbg, out, &data);

  				if (ret)
  					return ret;

  			}

  			out[cnt] ^= *pos;
  			pos++;
  			cnt++;
  			len--;

  		}

  	}

  	/* 10.4.3 step 4.2 for last block */
  	if (cnt)

  		ret = drbg_kcapi_sym(drbg, out, &data);

  
  	return ret;

  }
  
  /*
   * scratchpad usage: drbg_ctr_update is interlinked with drbg_ctr_df
   * (and drbg_ctr_bcc, but this function does not need any temporary buffers),
   * the scratchpad is used as follows:
   * drbg_ctr_update:
   *	temp
   *		start: drbg->scratchpad
   *		length: drbg_statelen(drbg) + drbg_blocklen(drbg)
   *			note: the cipher writing into this variable works
   *			blocklen-wise. Now, when the statelen is not a multiple
   *			of blocklen, the generateion loop below "spills over"
   *			by at most blocklen. Thus, we need to give sufficient
   *			memory.
   *	df_data
   *		start: drbg->scratchpad +
   *				drbg_statelen(drbg) + drbg_blocklen(drbg)
   *		length: drbg_statelen(drbg)
   *
   * drbg_ctr_df:
   *	pad
   *		start: df_data + drbg_statelen(drbg)
   *		length: drbg_blocklen(drbg)
   *	iv
   *		start: pad + drbg_blocklen(drbg)
   *		length: drbg_blocklen(drbg)
   *	temp
   *		start: iv + drbg_blocklen(drbg)

   *		length: drbg_satelen(drbg) + drbg_blocklen(drbg)
   *			note: temp is the buffer that the BCC function operates
   *			on. BCC operates blockwise. drbg_statelen(drbg)
   *			is sufficient when the DRBG state length is a multiple
   *			of the block size. For AES192 (and maybe other ciphers)
   *			this is not correct and the length for temp is
   *			insufficient (yes, that also means for such ciphers,
   *			the final output of all BCC rounds are truncated).
   *			Therefore, add drbg_blocklen(drbg) to cover all
   *			possibilities.

   */
  
  /* Derivation Function for CTR DRBG as defined in 10.4.2 */
  static int drbg_ctr_df(struct drbg_state *drbg,
  		       unsigned char *df_data, size_t bytes_to_return,

  		       struct list_head *seedlist)

  {
  	int ret = -EFAULT;
  	unsigned char L_N[8];
  	/* S3 is input */
  	struct drbg_string S1, S2, S4, cipherin;

  	LIST_HEAD(bcc_list);

  	unsigned char *pad = df_data + drbg_statelen(drbg);
  	unsigned char *iv = pad + drbg_blocklen(drbg);
  	unsigned char *temp = iv + drbg_blocklen(drbg);
  	size_t padlen = 0;
  	unsigned int templen = 0;
  	/* 10.4.2 step 7 */
  	unsigned int i = 0;
  	/* 10.4.2 step 8 */
  	const 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;
  	size_t generated_len = 0;
  	size_t inputlen = 0;

  	struct drbg_string *seed = NULL;

  
  	memset(pad, 0, drbg_blocklen(drbg));
  	memset(iv, 0, drbg_blocklen(drbg));

  
  	/* 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 */

  	list_for_each_entry(seed, seedlist, list)
  		inputlen += seed->len;

  	drbg_cpu_to_be32(inputlen, &L_N[0]);

  
  	/* 10.4.2 step 3 */

  	drbg_cpu_to_be32(bytes_to_return, &L_N[4]);

  
  	/* 10.4.2 step 5: length is L_N, input_string, one byte, padding */
  	padlen = (inputlen + sizeof(L_N) + 1) % (drbg_blocklen(drbg));
  	/* wrap the padlen appropriately */
  	if (padlen)
  		padlen = drbg_blocklen(drbg) - padlen;
  	/*
  	 * pad / padlen contains the 0x80 byte and the following zero bytes.
  	 * As the calculated padlen value only covers the number of zero
  	 * bytes, this value has to be incremented by one for the 0x80 byte.
  	 */
  	padlen++;
  	pad[0] = 0x80;
  
  	/* 10.4.2 step 4 -- first fill the linked list and then order it */
  	drbg_string_fill(&S1, iv, drbg_blocklen(drbg));

  	list_add_tail(&S1.list, &bcc_list);

  	drbg_string_fill(&S2, L_N, sizeof(L_N));

  	list_add_tail(&S2.list, &bcc_list);
  	list_splice_tail(seedlist, &bcc_list);

  	drbg_string_fill(&S4, pad, padlen);

  	list_add_tail(&S4.list, &bcc_list);

  
  	/* 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_cpu_to_be32(i, iv);

  		/* 10.4.2 step 9.2 -- BCC and concatenation with temp */

  		ret = drbg_ctr_bcc(drbg, temp + templen, K, &bcc_list);

  		if (ret)
  			goto out;
  		/* 10.4.2 step 9.3 */
  		i++;
  		templen += drbg_blocklen(drbg);
  	}
  
  	/* 10.4.2 step 11 */
  	X = temp + (drbg_keylen(drbg));
  	drbg_string_fill(&cipherin, X, drbg_blocklen(drbg));
  
  	/* 10.4.2 step 12: overwriting of outval is implemented in next step */
  
  	/* 10.4.2 step 13 */

  	drbg_kcapi_symsetkey(drbg, temp);

  	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 based on
  		 * the implementation of the cipher function callback
  		 */

  		ret = drbg_kcapi_sym(drbg, 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(df_data + generated_len, X, blocklen);
  		generated_len += blocklen;
  	}
  
  	ret = 0;
  
  out:

  	memset(iv, 0, drbg_blocklen(drbg));

  	memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));

  	memset(pad, 0, drbg_blocklen(drbg));

  	return ret;
  }

  /*
   * update function of CTR DRBG as defined in 10.2.1.2
   *
   * The reseed variable has an enhanced meaning compared to the update
   * functions of the other DRBGs as follows:
   * 0 => initial seed from initialization
   * 1 => reseed via drbg_seed
   * 2 => first invocation from drbg_ctr_update when addtl is present. In
   *      this case, the df_data scratchpad is not deleted so that it is
   *      available for another calls to prevent calling the DF function
   *      again.
   * 3 => second invocation from drbg_ctr_update. When the update function
   *      was called with addtl, the df_data memory already contains the
   *      DFed addtl information and we do not need to call DF again.
   */

  static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed,
  			   int reseed)

  {
  	int ret = -EFAULT;
  	/* 10.2.1.2 step 1 */
  	unsigned char *temp = drbg->scratchpad;
  	unsigned char *df_data = drbg->scratchpad + drbg_statelen(drbg) +
  				 drbg_blocklen(drbg);

  	if (3 > reseed)
  		memset(df_data, 0, drbg_statelen(drbg));

  	if (!reseed) {
  		/*
  		 * The DRBG uses the CTR mode of the underlying AES cipher. The
  		 * CTR mode increments the counter value after the AES operation
  		 * but SP800-90A requires that the counter is incremented before
  		 * the AES operation. Hence, we increment it at the time we set
  		 * it by one.
  		 */
  		crypto_inc(drbg->V, drbg_blocklen(drbg));
  
  		ret = crypto_skcipher_setkey(drbg->ctr_handle, drbg->C,
  					     drbg_keylen(drbg));

  		if (ret)
  			goto out;
  	}

  	/* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */
  	if (seed) {
  		ret = drbg_ctr_df(drbg, df_data, drbg_statelen(drbg), seed);

  		if (ret)
  			goto out;

  	}

  	ret = drbg_kcapi_sym_ctr(drbg, df_data, drbg_statelen(drbg),
  				 temp, drbg_statelen(drbg));

  	if (ret)
  		return ret;

  	/* 10.2.1.2 step 5 */

  	ret = crypto_skcipher_setkey(drbg->ctr_handle, temp,

  				     drbg_keylen(drbg));
  	if (ret)
  		goto out;

  	/* 10.2.1.2 step 6 */
  	memcpy(drbg->V, temp + drbg_keylen(drbg), drbg_blocklen(drbg));

  	/* See above: increment counter by one to compensate timing of CTR op */
  	crypto_inc(drbg->V, drbg_blocklen(drbg));

  	ret = 0;
  
  out:

  	memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));

  	if (2 != reseed)

  		memset(df_data, 0, drbg_statelen(drbg));

  	return ret;
  }
  
  /*
   * scratchpad use: drbg_ctr_update is called independently from
   * drbg_ctr_extract_bytes. Therefore, the scratchpad is reused
   */
  /* Generate function of CTR DRBG as defined in 10.2.1.5.2 */
  static int drbg_ctr_generate(struct drbg_state *drbg,
  			     unsigned char *buf, unsigned int buflen,

  			     struct list_head *addtl)

  {

  	int ret;
  	int len = min_t(int, buflen, INT_MAX);

  	/* 10.2.1.5.2 step 2 */

  	if (addtl && !list_empty(addtl)) {
  		ret = drbg_ctr_update(drbg, addtl, 2);

  		if (ret)
  			return 0;
  	}
  
  	/* 10.2.1.5.2 step 4.1 */

  	ret = drbg_kcapi_sym_ctr(drbg, NULL, 0, buf, len);

  	if (ret)
  		return ret;

  	/* 10.2.1.5.2 step 6 */
  	ret = drbg_ctr_update(drbg, NULL, 3);

  	if (ret)
  		len = ret;

  	return len;
  }

  static const struct drbg_state_ops drbg_ctr_ops = {

  	.update		= drbg_ctr_update,
  	.generate	= drbg_ctr_generate,
  	.crypto_init	= drbg_init_sym_kernel,
  	.crypto_fini	= drbg_fini_sym_kernel,
  };
  #endif /* CONFIG_CRYPTO_DRBG_CTR */
  
  /******************************************************************
   * HMAC DRBG callback functions
   ******************************************************************/
  
  #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)

  static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
  			   const struct list_head *in);
  static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
  				  const unsigned char *key);

  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_HMAC

  #define CRYPTO_DRBG_HMAC_STRING "HMAC "

  MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha512");
  MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha512");
  MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha384");
  MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha384");
  MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha256");
  MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha256");
  MODULE_ALIAS_CRYPTO("drbg_pr_hmac_sha1");
  MODULE_ALIAS_CRYPTO("drbg_nopr_hmac_sha1");

  /* update function of HMAC DRBG as defined in 10.1.2.2 */

  static int drbg_hmac_update(struct drbg_state *drbg, struct list_head *seed,
  			    int reseed)

  {
  	int ret = -EFAULT;
  	int i = 0;

  	struct drbg_string seed1, seed2, vdata;
  	LIST_HEAD(seedlist);
  	LIST_HEAD(vdatalist);

  	if (!reseed) {

  		/* 10.1.2.3 step 2 -- memset(0) of C is implicit with kzalloc */

  		memset(drbg->V, 1, drbg_statelen(drbg));

  		drbg_kcapi_hmacsetkey(drbg, drbg->C);
  	}

  
  	drbg_string_fill(&seed1, drbg->V, drbg_statelen(drbg));

  	list_add_tail(&seed1.list, &seedlist);

  	/* buffer of seed2 will be filled in for loop below with one byte */
  	drbg_string_fill(&seed2, NULL, 1);

  	list_add_tail(&seed2.list, &seedlist);

  	/* input data of seed is allowed to be NULL at this point */

  	if (seed)
  		list_splice_tail(seed, &seedlist);

  	drbg_string_fill(&vdata, drbg->V, drbg_statelen(drbg));
  	list_add_tail(&vdata.list, &vdatalist);

  	for (i = 2; 0 < i; i--) {
  		/* first round uses 0x0, second 0x1 */
  		unsigned char prefix = DRBG_PREFIX0;
  		if (1 == i)
  			prefix = DRBG_PREFIX1;
  		/* 10.1.2.2 step 1 and 4 -- concatenation and HMAC for key */
  		seed2.buf = &prefix;

  		ret = drbg_kcapi_hash(drbg, drbg->C, &seedlist);

  		if (ret)
  			return ret;

  		drbg_kcapi_hmacsetkey(drbg, drbg->C);

  
  		/* 10.1.2.2 step 2 and 5 -- HMAC for V */

  		ret = drbg_kcapi_hash(drbg, drbg->V, &vdatalist);

  		if (ret)
  			return ret;
  
  		/* 10.1.2.2 step 3 */

  		if (!seed)

  			return ret;
  	}
  
  	return 0;
  }
  
  /* generate function of HMAC DRBG as defined in 10.1.2.5 */
  static int drbg_hmac_generate(struct drbg_state *drbg,
  			      unsigned char *buf,
  			      unsigned int buflen,

  			      struct list_head *addtl)

  {
  	int len = 0;
  	int ret = 0;
  	struct drbg_string data;

  	LIST_HEAD(datalist);

  
  	/* 10.1.2.5 step 2 */

  	if (addtl && !list_empty(addtl)) {
  		ret = drbg_hmac_update(drbg, addtl, 1);

  		if (ret)
  			return ret;
  	}
  
  	drbg_string_fill(&data, drbg->V, drbg_statelen(drbg));

  	list_add_tail(&data.list, &datalist);

  	while (len < buflen) {
  		unsigned int outlen = 0;
  		/* 10.1.2.5 step 4.1 */

  		ret = drbg_kcapi_hash(drbg, drbg->V, &datalist);

  		if (ret)
  			return ret;
  		outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
  			  drbg_blocklen(drbg) : (buflen - len);

  
  		/* 10.1.2.5 step 4.2 */
  		memcpy(buf + len, drbg->V, outlen);
  		len += outlen;
  	}
  
  	/* 10.1.2.5 step 6 */

  	if (addtl && !list_empty(addtl))
  		ret = drbg_hmac_update(drbg, addtl, 1);
  	else

  		ret = drbg_hmac_update(drbg, NULL, 1);

  	if (ret)
  		return ret;
  
  	return len;
  }

  static const struct drbg_state_ops drbg_hmac_ops = {

  	.update		= drbg_hmac_update,
  	.generate	= drbg_hmac_generate,
  	.crypto_init	= drbg_init_hash_kernel,
  	.crypto_fini	= drbg_fini_hash_kernel,

  };
  #endif /* CONFIG_CRYPTO_DRBG_HMAC */
  
  /******************************************************************
   * Hash DRBG callback functions
   ******************************************************************/
  
  #ifdef CONFIG_CRYPTO_DRBG_HASH

  #define CRYPTO_DRBG_HASH_STRING "HASH "

  MODULE_ALIAS_CRYPTO("drbg_pr_sha512");
  MODULE_ALIAS_CRYPTO("drbg_nopr_sha512");
  MODULE_ALIAS_CRYPTO("drbg_pr_sha384");
  MODULE_ALIAS_CRYPTO("drbg_nopr_sha384");
  MODULE_ALIAS_CRYPTO("drbg_pr_sha256");
  MODULE_ALIAS_CRYPTO("drbg_nopr_sha256");
  MODULE_ALIAS_CRYPTO("drbg_pr_sha1");
  MODULE_ALIAS_CRYPTO("drbg_nopr_sha1");

  /*

   * Increment buffer
   *
   * @dst buffer to increment
   * @add value to add
   */
  static inline void drbg_add_buf(unsigned char *dst, size_t dstlen,
  				const unsigned char *add, size_t addlen)
  {
  	/* implied: dstlen > addlen */
  	unsigned char *dstptr;
  	const unsigned char *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--;
  	}
  }
  
  /*

   * scratchpad usage: as drbg_hash_update and drbg_hash_df are used
   * interlinked, the scratchpad is used as follows:
   * drbg_hash_update
   *	start: drbg->scratchpad
   *	length: drbg_statelen(drbg)
   * drbg_hash_df:
   *	start: drbg->scratchpad + drbg_statelen(drbg)
   *	length: drbg_blocklen(drbg)
   *
   * drbg_hash_process_addtl uses the scratchpad, but fully completes
   * before either of the functions mentioned before are invoked. Therefore,
   * drbg_hash_process_addtl does not need to be specifically considered.
   */
  
  /* Derivation Function for Hash DRBG as defined in 10.4.1 */
  static int drbg_hash_df(struct drbg_state *drbg,
  			unsigned char *outval, size_t outlen,

  			struct list_head *entropylist)

  {
  	int ret = 0;
  	size_t len = 0;
  	unsigned char input[5];
  	unsigned char *tmp = drbg->scratchpad + drbg_statelen(drbg);

  	struct drbg_string data;

  	/* 10.4.1 step 3 */
  	input[0] = 1;

  	drbg_cpu_to_be32((outlen * 8), &input[1]);

  
  	/* 10.4.1 step 4.1 -- concatenation of data for input into hash */

  	drbg_string_fill(&data, input, 5);
  	list_add(&data.list, entropylist);

  
  	/* 10.4.1 step 4 */
  	while (len < outlen) {
  		short blocklen = 0;
  		/* 10.4.1 step 4.1 */

  		ret = drbg_kcapi_hash(drbg, tmp, entropylist);

  		if (ret)
  			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:

  	memset(tmp, 0, drbg_blocklen(drbg));

  	return ret;
  }
  
  /* update function for Hash DRBG as defined in 10.1.1.2 / 10.1.1.3 */

  static int drbg_hash_update(struct drbg_state *drbg, struct list_head *seed,

  			    int reseed)
  {
  	int ret = 0;
  	struct drbg_string data1, data2;

  	LIST_HEAD(datalist);
  	LIST_HEAD(datalist2);

  	unsigned char *V = drbg->scratchpad;
  	unsigned char prefix = DRBG_PREFIX1;

  	if (!seed)
  		return -EINVAL;
  
  	if (reseed) {
  		/* 10.1.1.3 step 1 */
  		memcpy(V, drbg->V, drbg_statelen(drbg));
  		drbg_string_fill(&data1, &prefix, 1);

  		list_add_tail(&data1.list, &datalist);

  		drbg_string_fill(&data2, V, drbg_statelen(drbg));

  		list_add_tail(&data2.list, &datalist);

  	}

  	list_splice_tail(seed, &datalist);

  
  	/* 10.1.1.2 / 10.1.1.3 step 2 and 3 */

  	ret = drbg_hash_df(drbg, drbg->V, drbg_statelen(drbg), &datalist);

  	if (ret)
  		goto out;
  
  	/* 10.1.1.2 / 10.1.1.3 step 4  */
  	prefix = DRBG_PREFIX0;
  	drbg_string_fill(&data1, &prefix, 1);

  	list_add_tail(&data1.list, &datalist2);

  	drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));

  	list_add_tail(&data2.list, &datalist2);

  	/* 10.1.1.2 / 10.1.1.3 step 4 */

  	ret = drbg_hash_df(drbg, drbg->C, drbg_statelen(drbg), &datalist2);

  
  out:

  	memset(drbg->scratchpad, 0, drbg_statelen(drbg));

  	return ret;
  }
  
  /* processing of additional information string for Hash DRBG */
  static int drbg_hash_process_addtl(struct drbg_state *drbg,

  				   struct list_head *addtl)

  {
  	int ret = 0;
  	struct drbg_string data1, data2;

  	LIST_HEAD(datalist);

  	unsigned char prefix = DRBG_PREFIX2;

  	/* 10.1.1.4 step 2 */

  	if (!addtl || list_empty(addtl))

  		return 0;
  
  	/* 10.1.1.4 step 2a */
  	drbg_string_fill(&data1, &prefix, 1);
  	drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));

  	list_add_tail(&data1.list, &datalist);
  	list_add_tail(&data2.list, &datalist);

  	list_splice_tail(addtl, &datalist);

  	ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);

  	if (ret)
  		goto out;
  
  	/* 10.1.1.4 step 2b */
  	drbg_add_buf(drbg->V, drbg_statelen(drbg),
  		     drbg->scratchpad, drbg_blocklen(drbg));
  
  out:

  	memset(drbg->scratchpad, 0, drbg_blocklen(drbg));

  	return ret;
  }
  
  /* Hashgen defined in 10.1.1.4 */
  static int drbg_hash_hashgen(struct drbg_state *drbg,
  			     unsigned char *buf,
  			     unsigned int buflen)
  {
  	int len = 0;
  	int ret = 0;
  	unsigned char *src = drbg->scratchpad;
  	unsigned char *dst = drbg->scratchpad + drbg_statelen(drbg);
  	struct drbg_string data;

  	LIST_HEAD(datalist);

  	/* 10.1.1.4 step hashgen 2 */
  	memcpy(src, drbg->V, drbg_statelen(drbg));
  
  	drbg_string_fill(&data, src, drbg_statelen(drbg));

  	list_add_tail(&data.list, &datalist);

  	while (len < buflen) {
  		unsigned int outlen = 0;
  		/* 10.1.1.4 step hashgen 4.1 */

  		ret = drbg_kcapi_hash(drbg, dst, &datalist);

  		if (ret) {
  			len = ret;
  			goto out;
  		}
  		outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
  			  drbg_blocklen(drbg) : (buflen - len);

  		/* 10.1.1.4 step hashgen 4.2 */
  		memcpy(buf + len, dst, outlen);
  		len += outlen;
  		/* 10.1.1.4 hashgen step 4.3 */
  		if (len < buflen)

  			crypto_inc(src, drbg_statelen(drbg));

  	}
  
  out:

  	memset(drbg->scratchpad, 0,

  	       (drbg_statelen(drbg) + drbg_blocklen(drbg)));
  	return len;
  }
  
  /* generate function for Hash DRBG as defined in  10.1.1.4 */
  static int drbg_hash_generate(struct drbg_state *drbg,
  			      unsigned char *buf, unsigned int buflen,

  			      struct list_head *addtl)

  {
  	int len = 0;
  	int ret = 0;

  	union {
  		unsigned char req[8];

  		__be64 req_int;

  	} u;

  	unsigned char prefix = DRBG_PREFIX3;
  	struct drbg_string data1, data2;

  	LIST_HEAD(datalist);

  
  	/* 10.1.1.4 step 2 */
  	ret = drbg_hash_process_addtl(drbg, addtl);
  	if (ret)
  		return ret;
  	/* 10.1.1.4 step 3 */
  	len = drbg_hash_hashgen(drbg, buf, buflen);
  
  	/* this is the value H as documented in 10.1.1.4 */

  	/* 10.1.1.4 step 4 */
  	drbg_string_fill(&data1, &prefix, 1);

  	list_add_tail(&data1.list, &datalist);

  	drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));

  	list_add_tail(&data2.list, &datalist);

  	ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);

  	if (ret) {
  		len = ret;
  		goto out;
  	}
  
  	/* 10.1.1.4 step 5 */
  	drbg_add_buf(drbg->V, drbg_statelen(drbg),
  		     drbg->scratchpad, drbg_blocklen(drbg));
  	drbg_add_buf(drbg->V, drbg_statelen(drbg),
  		     drbg->C, drbg_statelen(drbg));

  	u.req_int = cpu_to_be64(drbg->reseed_ctr);
  	drbg_add_buf(drbg->V, drbg_statelen(drbg), u.req, 8);

  
  out:

  	memset(drbg->scratchpad, 0, drbg_blocklen(drbg));

  	return len;
  }
  
  /*
   * scratchpad usage: as update and generate are used isolated, both
   * can use the scratchpad
   */

  static const struct drbg_state_ops drbg_hash_ops = {

  	.update		= drbg_hash_update,
  	.generate	= drbg_hash_generate,
  	.crypto_init	= drbg_init_hash_kernel,
  	.crypto_fini	= drbg_fini_hash_kernel,
  };
  #endif /* CONFIG_CRYPTO_DRBG_HASH */
  
  /******************************************************************
   * Functions common for DRBG implementations
   ******************************************************************/

  static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed,

  			      int reseed, enum drbg_seed_state new_seed_state)

  {
  	int ret = drbg->d_ops->update(drbg, seed, reseed);
  
  	if (ret)
  		return ret;

  	drbg->seeded = new_seed_state;

  	/* 10.1.1.2 / 10.1.1.3 step 5 */
  	drbg->reseed_ctr = 1;

  	switch (drbg->seeded) {
  	case DRBG_SEED_STATE_UNSEEDED:
  		/* Impossible, but handle it to silence compiler warnings. */
  		fallthrough;
  	case DRBG_SEED_STATE_PARTIAL:
  		/*
  		 * Require frequent reseeds until the seed source is
  		 * fully initialized.
  		 */
  		drbg->reseed_threshold = 50;
  		break;
  
  	case DRBG_SEED_STATE_FULL:
  		/*
  		 * Seed source has become fully initialized, frequent
  		 * reseeds no longer required.
  		 */
  		drbg->reseed_threshold = drbg_max_requests(drbg);
  		break;
  	}

  	return ret;
  }

  static inline int drbg_get_random_bytes(struct drbg_state *drbg,
  					unsigned char *entropy,
  					unsigned int entropylen)
  {
  	int ret;
  
  	do {
  		get_random_bytes(entropy, entropylen);
  		ret = drbg_fips_continuous_test(drbg, entropy);
  		if (ret && ret != -EAGAIN)
  			return ret;
  	} while (ret);
  
  	return 0;
  }

  static int drbg_seed_from_random(struct drbg_state *drbg)

  {
  	struct drbg_string data;
  	LIST_HEAD(seedlist);

  	unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
  	unsigned char entropy[32];

  	int ret;

  	BUG_ON(!entropylen);
  	BUG_ON(entropylen > sizeof(entropy));

  	drbg_string_fill(&data, entropy, entropylen);

  	list_add_tail(&data.list, &seedlist);

  	ret = drbg_get_random_bytes(drbg, entropy, entropylen);
  	if (ret)

  		goto out;

  	ret = __drbg_seed(drbg, &seedlist, true, DRBG_SEED_STATE_FULL);

  out:

  	memzero_explicit(entropy, entropylen);

  	return ret;

  }

  /*
   * Seeding or reseeding of the DRBG
   *
   * @drbg: DRBG state struct
   * @pers: 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, struct drbg_string *pers,
  		     bool reseed)
  {

  	int ret;
  	unsigned char entropy[((32 + 16) * 2)];
  	unsigned int entropylen = drbg_sec_strength(drbg->core->flags);

  	struct drbg_string data1;

  	LIST_HEAD(seedlist);

  	enum drbg_seed_state new_seed_state = DRBG_SEED_STATE_FULL;

  
  	/* 9.1 / 9.2 / 9.3.1 step 3 */
  	if (pers && pers->len > (drbg_max_addtl(drbg))) {

  		pr_devel("DRBG: personalization string too long %zu
  ",

  			 pers->len);
  		return -EINVAL;
  	}

  	if (list_empty(&drbg->test_data.list)) {
  		drbg_string_fill(&data1, drbg->test_data.buf,
  				 drbg->test_data.len);

  		pr_devel("DRBG: using test entropy
  ");
  	} else {

  		/*
  		 * Gather entropy equal to the security strength of the DRBG.
  		 * With a derivation function, a nonce is required in addition
  		 * to the entropy. 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.
  		 */
  		BUG_ON(!entropylen);
  		if (!reseed)
  			entropylen = ((entropylen + 1) / 2) * 3;
  		BUG_ON((entropylen * 2) > sizeof(entropy));

  		/* Get seed from in-kernel /dev/urandom */

  		if (!rng_is_initialized())
  			new_seed_state = DRBG_SEED_STATE_PARTIAL;

  		ret = drbg_get_random_bytes(drbg, entropy, entropylen);
  		if (ret)
  			goto out;

  
  		if (!drbg->jent) {
  			drbg_string_fill(&data1, entropy, entropylen);
  			pr_devel("DRBG: (re)seeding with %u bytes of entropy
  ",
  				 entropylen);

  		} else {

  			/* Get seed from Jitter RNG */
  			ret = crypto_rng_get_bytes(drbg->jent,
  						   entropy + entropylen,
  						   entropylen);
  			if (ret) {
  				pr_devel("DRBG: jent failed with %d
  ", ret);

  
  				/*
  				 * Do not treat the transient failure of the
  				 * Jitter RNG as an error that needs to be
  				 * reported. The combined number of the
  				 * maximum reseed threshold times the maximum
  				 * number of Jitter RNG transient errors is
  				 * less than the reseed threshold required by
  				 * SP800-90A allowing us to treat the
  				 * transient errors as such.
  				 *
  				 * However, we mandate that at least the first
  				 * seeding operation must succeed with the
  				 * Jitter RNG.
  				 */
  				if (!reseed || ret != -EAGAIN)
  					goto out;

  			}
  
  			drbg_string_fill(&data1, entropy, entropylen * 2);
  			pr_devel("DRBG: (re)seeding with %u bytes of entropy
  ",
  				 entropylen * 2);

  		}

  	}

  	list_add_tail(&data1.list, &seedlist);

  
  	/*
  	 * concatenation of entropy with personalization str / addtl input)
  	 * the variable pers is directly handed in by the caller, so check its
  	 * contents whether it is appropriate
  	 */

  	if (pers && pers->buf && 0 < pers->len) {
  		list_add_tail(&pers->list, &seedlist);

  		pr_devel("DRBG: using personalization string
  ");
  	}

  	if (!reseed) {
  		memset(drbg->V, 0, drbg_statelen(drbg));
  		memset(drbg->C, 0, drbg_statelen(drbg));
  	}

  	ret = __drbg_seed(drbg, &seedlist, reseed, new_seed_state);

  out:

  	memzero_explicit(entropy, entropylen * 2);

  	return ret;
  }
  
  /* Free all substructures in a DRBG state without the DRBG state structure */
  static inline void drbg_dealloc_state(struct drbg_state *drbg)
  {
  	if (!drbg)
  		return;

  	kfree_sensitive(drbg->Vbuf);

  	drbg->Vbuf = NULL;

  	drbg->V = NULL;

  	kfree_sensitive(drbg->Cbuf);

  	drbg->Cbuf = NULL;

  	drbg->C = NULL;

  	kfree_sensitive(drbg->scratchpadbuf);

  	drbg->scratchpadbuf = NULL;

  	drbg->reseed_ctr = 0;

  	drbg->d_ops = NULL;
  	drbg->core = NULL;

  	if (IS_ENABLED(CONFIG_CRYPTO_FIPS)) {

  		kfree_sensitive(drbg->prev);

  		drbg->prev = NULL;
  		drbg->fips_primed = false;
  	}

  }
  
  /*
   * Allocate all sub-structures for a DRBG state.
   * The DRBG state structure must already be allocated.
   */
  static inline int drbg_alloc_state(struct drbg_state *drbg)
  {
  	int ret = -ENOMEM;
  	unsigned int sb_size = 0;

  	switch (drbg->core->flags & DRBG_TYPE_MASK) {
  #ifdef CONFIG_CRYPTO_DRBG_HMAC
  	case DRBG_HMAC:
  		drbg->d_ops = &drbg_hmac_ops;
  		break;
  #endif /* CONFIG_CRYPTO_DRBG_HMAC */
  #ifdef CONFIG_CRYPTO_DRBG_HASH
  	case DRBG_HASH:
  		drbg->d_ops = &drbg_hash_ops;
  		break;
  #endif /* CONFIG_CRYPTO_DRBG_HASH */
  #ifdef CONFIG_CRYPTO_DRBG_CTR
  	case DRBG_CTR:
  		drbg->d_ops = &drbg_ctr_ops;
  		break;
  #endif /* CONFIG_CRYPTO_DRBG_CTR */
  	default:
  		ret = -EOPNOTSUPP;
  		goto err;
  	}

  	ret = drbg->d_ops->crypto_init(drbg);
  	if (ret < 0)

  		goto err;

  
  	drbg->Vbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL);

  	if (!drbg->Vbuf) {
  		ret = -ENOMEM;

  		goto fini;

  	}

  	drbg->V = PTR_ALIGN(drbg->Vbuf, ret + 1);
  	drbg->Cbuf = kmalloc(drbg_statelen(drbg) + ret, GFP_KERNEL);

  	if (!drbg->Cbuf) {
  		ret = -ENOMEM;

  		goto fini;

  	}

  	drbg->C = PTR_ALIGN(drbg->Cbuf, ret + 1);

  	/* scratchpad is only generated for CTR and Hash */
  	if (drbg->core->flags & DRBG_HMAC)
  		sb_size = 0;
  	else if (drbg->core->flags & DRBG_CTR)
  		sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg) + /* temp */
  			  drbg_statelen(drbg) +	/* df_data */
  			  drbg_blocklen(drbg) +	/* pad */
  			  drbg_blocklen(drbg) +	/* iv */

  			  drbg_statelen(drbg) + drbg_blocklen(drbg); /* temp */

  	else
  		sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg);
  
  	if (0 < sb_size) {

  		drbg->scratchpadbuf = kzalloc(sb_size + ret, GFP_KERNEL);

  		if (!drbg->scratchpadbuf) {
  			ret = -ENOMEM;

  			goto fini;

  		}

  		drbg->scratchpad = PTR_ALIGN(drbg->scratchpadbuf, ret + 1);

  	}

  	if (IS_ENABLED(CONFIG_CRYPTO_FIPS)) {
  		drbg->prev = kzalloc(drbg_sec_strength(drbg->core->flags),
  				     GFP_KERNEL);

  		if (!drbg->prev) {
  			ret = -ENOMEM;

  			goto fini;

  		}

  		drbg->fips_primed = false;
  	}

  	return 0;

  fini:
  	drbg->d_ops->crypto_fini(drbg);

  err:
  	drbg_dealloc_state(drbg);
  	return ret;
  }

  /*************************************************************************
   * DRBG interface functions
   *************************************************************************/
  
  /*
   * 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 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.
   *

   * return: 0 when all bytes are generated; < 0 in case of an error

   */
  static int drbg_generate(struct drbg_state *drbg,
  			 unsigned char *buf, unsigned int buflen,
  			 struct drbg_string *addtl)
  {
  	int len = 0;

  	LIST_HEAD(addtllist);

  	if (!drbg->core) {
  		pr_devel("DRBG: not yet seeded
  ");
  		return -EINVAL;
  	}

  	if (0 == buflen || !buf) {
  		pr_devel("DRBG: no output buffer provided
  ");
  		return -EINVAL;
  	}
  	if (addtl && NULL == addtl->buf && 0 < addtl->len) {
  		pr_devel("DRBG: wrong format of additional information
  ");
  		return -EINVAL;
  	}

  	/* 9.3.1 step 2 */
  	len = -EINVAL;

  	if (buflen > (drbg_max_request_bytes(drbg))) {

  		pr_devel("DRBG: requested random numbers too large %u
  ",
  			 buflen);
  		goto err;
  	}
  
  	/* 9.3.1 step 3 is implicit with the chosen DRBG */
  
  	/* 9.3.1 step 4 */

  	if (addtl && addtl->len > (drbg_max_addtl(drbg))) {

  		pr_devel("DRBG: additional information string too long %zu
  ",
  			 addtl->len);
  		goto err;
  	}
  	/* 9.3.1 step 5 is implicit with the chosen DRBG */
  
  	/*
  	 * 9.3.1 step 6 and 9 supplemented by 9.3.2 step c is implemented
  	 * here. The spec is a bit convoluted here, we make it simpler.
  	 */

  	if (drbg->reseed_threshold < drbg->reseed_ctr)

  		drbg->seeded = DRBG_SEED_STATE_UNSEEDED;

  	if (drbg->pr || drbg->seeded == DRBG_SEED_STATE_UNSEEDED) {

  		pr_devel("DRBG: reseeding before generation (prediction "
  			 "resistance: %s, state %s)
  ",
  			 drbg->pr ? "true" : "false",

  			 (drbg->seeded ==  DRBG_SEED_STATE_FULL ?
  			  "seeded" : "unseeded"));

  		/* 9.3.1 steps 7.1 through 7.3 */

  		len = drbg_seed(drbg, addtl, true);

  		if (len)
  			goto err;
  		/* 9.3.1 step 7.4 */
  		addtl = NULL;

  	} else if (rng_is_initialized() &&
  		   drbg->seeded == DRBG_SEED_STATE_PARTIAL) {
  		len = drbg_seed_from_random(drbg);
  		if (len)
  			goto err;

  	}

  	if (addtl && 0 < addtl->len)
  		list_add_tail(&addtl->list, &addtllist);

  	/* 9.3.1 step 8 and 10 */

  	len = drbg->d_ops->generate(drbg, buf, buflen, &addtllist);

  
  	/* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */

  	drbg->reseed_ctr++;

  	if (0 >= len)
  		goto err;
  
  	/*
  	 * Section 11.3.3 requires to re-perform self tests after some
  	 * generated random numbers. The chosen value after which self
  	 * test is performed is arbitrary, but it should be reasonable.
  	 * However, we do not perform the self tests because of the following
  	 * reasons: it is mathematically impossible that the initial self tests
  	 * were successfully and the following are not. If the initial would
  	 * pass and the following would not, the kernel integrity is violated.
  	 * In this case, the entire kernel operation is questionable and it
  	 * is unlikely that the integrity violation only affects the
  	 * correct operation of the DRBG.
  	 *
  	 * Albeit the following code is commented out, it is provided in
  	 * case somebody has a need to implement the test of 11.3.3.
  	 */
  #if 0

  	if (drbg->reseed_ctr && !(drbg->reseed_ctr % 4096)) {

  		int err = 0;
  		pr_devel("DRBG: start to perform self test
  ");
  		if (drbg->core->flags & DRBG_HMAC)
  			err = alg_test("drbg_pr_hmac_sha256",
  				       "drbg_pr_hmac_sha256", 0, 0);
  		else if (drbg->core->flags & DRBG_CTR)
  			err = alg_test("drbg_pr_ctr_aes128",
  				       "drbg_pr_ctr_aes128", 0, 0);
  		else
  			err = alg_test("drbg_pr_sha256",
  				       "drbg_pr_sha256", 0, 0);
  		if (err) {
  			pr_err("DRBG: periodical self test failed
  ");
  			/*
  			 * uninstantiate implies that from now on, only errors
  			 * are returned when reusing this DRBG cipher handle
  			 */
  			drbg_uninstantiate(drbg);

  			return 0;
  		} else {
  			pr_devel("DRBG: self test successful
  ");
  		}
  	}
  #endif

  	/*
  	 * All operations were successful, return 0 as mandated by
  	 * the kernel crypto API interface.
  	 */
  	len = 0;

  err:

  	return len;
  }
  
  /*
   * Wrapper around drbg_generate which can pull arbitrary long strings
   * from the DRBG without hitting the maximum request limitation.
   *
   * Parameters: see drbg_generate
   * Return codes: see drbg_generate -- if one drbg_generate request fails,
   *		 the entire drbg_generate_long request fails
   */
  static int drbg_generate_long(struct drbg_state *drbg,
  			      unsigned char *buf, unsigned int buflen,
  			      struct drbg_string *addtl)
  {

  	unsigned int len = 0;

  	unsigned int slice = 0;
  	do {

  		int err = 0;

  		unsigned int chunk = 0;
  		slice = ((buflen - len) / drbg_max_request_bytes(drbg));
  		chunk = slice ? drbg_max_request_bytes(drbg) : (buflen - len);

  		mutex_lock(&drbg->drbg_mutex);

  		err = drbg_generate(drbg, buf + len, chunk, addtl);

  		mutex_unlock(&drbg->drbg_mutex);

  		if (0 > err)
  			return err;
  		len += chunk;

  	} while (slice > 0 && (len < buflen));

  	return 0;

  }

  static int drbg_prepare_hrng(struct drbg_state *drbg)
  {

  	/* We do not need an HRNG in test mode. */
  	if (list_empty(&drbg->test_data.list))
  		return 0;

  	drbg->jent = crypto_alloc_rng("jitterentropy_rng", 0, 0);

  	return 0;

  }

  /*
   * 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.
   * @coreref reference to core
   * @pr prediction resistance enabled
   *
   * return
   *	0 on success
   *	error value otherwise
   */
  static int drbg_instantiate(struct drbg_state *drbg, struct drbg_string *pers,
  			    int coreref, bool pr)
  {

  	int ret;
  	bool reseed = true;

  
  	pr_devel("DRBG: Initializing DRBG core %d with prediction resistance "
  		 "%s
  ", coreref, pr ? "enabled" : "disabled");

  	mutex_lock(&drbg->drbg_mutex);

  
  	/* 9.1 step 1 is implicit with the selected DRBG type */
  
  	/*
  	 * 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 */

  	if (!drbg->core) {
  		drbg->core = &drbg_cores[coreref];
  		drbg->pr = pr;

  		drbg->seeded = DRBG_SEED_STATE_UNSEEDED;

  		drbg->reseed_threshold = drbg_max_requests(drbg);

  		ret = drbg_alloc_state(drbg);
  		if (ret)
  			goto unlock;

  		ret = drbg_prepare_hrng(drbg);
  		if (ret)
  			goto free_everything;
  
  		if (IS_ERR(drbg->jent)) {
  			ret = PTR_ERR(drbg->jent);
  			drbg->jent = NULL;
  			if (fips_enabled || ret != -ENOENT)
  				goto free_everything;
  			pr_info("DRBG: Continuing without Jitter RNG
  ");
  		}

  		reseed = false;
  	}
  
  	ret = drbg_seed(drbg, pers, reseed);

  	if (ret && !reseed)
  		goto free_everything;

  	mutex_unlock(&drbg->drbg_mutex);

  	return ret;

  unlock:
  	mutex_unlock(&drbg->drbg_mutex);

  	return ret;

  
  free_everything:
  	mutex_unlock(&drbg->drbg_mutex);
  	drbg_uninstantiate(drbg);
  	return ret;

  }
  
  /*
   * DRBG uninstantiate function as required by SP800-90A - this function
   * frees all buffers and the DRBG handle
   *
   * @drbg DRBG state handle
   *
   * return
   *	0 on success
   */
  static int drbg_uninstantiate(struct drbg_state *drbg)
  {

  	if (!IS_ERR_OR_NULL(drbg->jent))
  		crypto_free_rng(drbg->jent);
  	drbg->jent = NULL;

  	if (drbg->d_ops)
  		drbg->d_ops->crypto_fini(drbg);

  	drbg_dealloc_state(drbg);
  	/* no scrubbing of test_data -- this shall survive an uninstantiate */

  	return 0;
  }
  
  /*
   * Helper function for setting the test data in the DRBG
   *
   * @drbg DRBG state handle

   * @data test data
   * @len test data length

   */

  static void drbg_kcapi_set_entropy(struct crypto_rng *tfm,
  				   const u8 *data, unsigned int len)

  {

  	struct drbg_state *drbg = crypto_rng_ctx(tfm);
  
  	mutex_lock(&drbg->drbg_mutex);
  	drbg_string_fill(&drbg->test_data, data, len);

  	mutex_unlock(&drbg->drbg_mutex);

  }
  
  /***************************************************************
   * Kernel crypto API cipher invocations requested by DRBG
   ***************************************************************/
  
  #if defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_HMAC)
  struct sdesc {
  	struct shash_desc shash;
  	char ctx[];
  };
  
  static int drbg_init_hash_kernel(struct drbg_state *drbg)
  {
  	struct sdesc *sdesc;
  	struct crypto_shash *tfm;
  
  	tfm = crypto_alloc_shash(drbg->core->backend_cra_name, 0, 0);
  	if (IS_ERR(tfm)) {

  		pr_info("DRBG: could not allocate digest TFM handle: %s
  ",
  				drbg->core->backend_cra_name);

  		return PTR_ERR(tfm);
  	}
  	BUG_ON(drbg_blocklen(drbg) != crypto_shash_digestsize(tfm));
  	sdesc = kzalloc(sizeof(struct shash_desc) + crypto_shash_descsize(tfm),
  			GFP_KERNEL);
  	if (!sdesc) {
  		crypto_free_shash(tfm);
  		return -ENOMEM;
  	}
  
  	sdesc->shash.tfm = tfm;

  	drbg->priv_data = sdesc;

  
  	return crypto_shash_alignmask(tfm);

  }
  
  static int drbg_fini_hash_kernel(struct drbg_state *drbg)
  {
  	struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
  	if (sdesc) {
  		crypto_free_shash(sdesc->shash.tfm);

  		kfree_sensitive(sdesc);

  	}
  	drbg->priv_data = NULL;
  	return 0;
  }

  static void drbg_kcapi_hmacsetkey(struct drbg_state *drbg,
  				  const unsigned char *key)
  {
  	struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;
  
  	crypto_shash_setkey(sdesc->shash.tfm, key, drbg_statelen(drbg));
  }
  
  static int drbg_kcapi_hash(struct drbg_state *drbg, unsigned char *outval,
  			   const struct list_head *in)

  {
  	struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;

  	struct drbg_string *input = NULL;

  	crypto_shash_init(&sdesc->shash);

  	list_for_each_entry(input, in, list)
  		crypto_shash_update(&sdesc->shash, input->buf, input->len);

  	return crypto_shash_final(&sdesc->shash, outval);
  }
  #endif /* (CONFIG_CRYPTO_DRBG_HASH || CONFIG_CRYPTO_DRBG_HMAC) */
  
  #ifdef CONFIG_CRYPTO_DRBG_CTR

  static int drbg_fini_sym_kernel(struct drbg_state *drbg)
  {
  	struct crypto_cipher *tfm =
  		(struct crypto_cipher *)drbg->priv_data;
  	if (tfm)
  		crypto_free_cipher(tfm);
  	drbg->priv_data = NULL;
  
  	if (drbg->ctr_handle)
  		crypto_free_skcipher(drbg->ctr_handle);
  	drbg->ctr_handle = NULL;
  
  	if (drbg->ctr_req)

  		skcipher_request_free(drbg->ctr_req);

  	drbg->ctr_req = NULL;

  	kfree(drbg->outscratchpadbuf);
  	drbg->outscratchpadbuf = NULL;

  	return 0;
  }

  static int drbg_init_sym_kernel(struct drbg_state *drbg)
  {

  	struct crypto_cipher *tfm;

  	struct crypto_skcipher *sk_tfm;
  	struct skcipher_request *req;
  	unsigned int alignmask;
  	char ctr_name[CRYPTO_MAX_ALG_NAME];

  	tfm = crypto_alloc_cipher(drbg->core->backend_cra_name, 0, 0);

  	if (IS_ERR(tfm)) {

  		pr_info("DRBG: could not allocate cipher TFM handle: %s
  ",
  				drbg->core->backend_cra_name);

  		return PTR_ERR(tfm);
  	}

  	BUG_ON(drbg_blocklen(drbg) != crypto_cipher_blocksize(tfm));

  	drbg->priv_data = tfm;

  	if (snprintf(ctr_name, CRYPTO_MAX_ALG_NAME, "ctr(%s)",
  	    drbg->core->backend_cra_name) >= CRYPTO_MAX_ALG_NAME) {
  		drbg_fini_sym_kernel(drbg);
  		return -EINVAL;
  	}
  	sk_tfm = crypto_alloc_skcipher(ctr_name, 0, 0);
  	if (IS_ERR(sk_tfm)) {
  		pr_info("DRBG: could not allocate CTR cipher TFM handle: %s
  ",
  				ctr_name);
  		drbg_fini_sym_kernel(drbg);
  		return PTR_ERR(sk_tfm);
  	}
  	drbg->ctr_handle = sk_tfm;

  	crypto_init_wait(&drbg->ctr_wait);

  
  	req = skcipher_request_alloc(sk_tfm, GFP_KERNEL);
  	if (!req) {
  		pr_info("DRBG: could not allocate request queue
  ");
  		drbg_fini_sym_kernel(drbg);

  		return -ENOMEM;

  	}
  	drbg->ctr_req = req;

  	skcipher_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG |
  						CRYPTO_TFM_REQ_MAY_SLEEP,
  					crypto_req_done, &drbg->ctr_wait);

  
  	alignmask = crypto_skcipher_alignmask(sk_tfm);

  	drbg->outscratchpadbuf = kmalloc(DRBG_OUTSCRATCHLEN + alignmask,
  					 GFP_KERNEL);
  	if (!drbg->outscratchpadbuf) {
  		drbg_fini_sym_kernel(drbg);
  		return -ENOMEM;
  	}
  	drbg->outscratchpad = (u8 *)PTR_ALIGN(drbg->outscratchpadbuf,
  					      alignmask + 1);

  	sg_init_table(&drbg->sg_in, 1);

  	sg_init_one(&drbg->sg_out, drbg->outscratchpad, DRBG_OUTSCRATCHLEN);

  	return alignmask;

  }

  static void drbg_kcapi_symsetkey(struct drbg_state *drbg,
  				 const unsigned char *key)

  {

  	struct crypto_cipher *tfm =
  		(struct crypto_cipher *)drbg->priv_data;

  	crypto_cipher_setkey(tfm, key, (drbg_keylen(drbg)));

  }
  
  static int drbg_kcapi_sym(struct drbg_state *drbg, unsigned char *outval,
  			  const struct drbg_string *in)
  {
  	struct crypto_cipher *tfm =
  		(struct crypto_cipher *)drbg->priv_data;

  	/* there is only component in *in */
  	BUG_ON(in->len < drbg_blocklen(drbg));
  	crypto_cipher_encrypt_one(tfm, outval, in->buf);
  	return 0;

  }

  static int drbg_kcapi_sym_ctr(struct drbg_state *drbg,
  			      u8 *inbuf, u32 inlen,
  			      u8 *outbuf, u32 outlen)

  {

  	struct scatterlist *sg_in = &drbg->sg_in, *sg_out = &drbg->sg_out;

  	u32 scratchpad_use = min_t(u32, outlen, DRBG_OUTSCRATCHLEN);

  	int ret;

  	if (inbuf) {
  		/* Use caller-provided input buffer */
  		sg_set_buf(sg_in, inbuf, inlen);
  	} else {
  		/* Use scratchpad for in-place operation */
  		inlen = scratchpad_use;
  		memset(drbg->outscratchpad, 0, scratchpad_use);
  		sg_set_buf(sg_in, drbg->outscratchpad, scratchpad_use);
  	}

  
  	while (outlen) {

  		u32 cryptlen = min3(inlen, outlen, (u32)DRBG_OUTSCRATCHLEN);

  		/* Output buffer may not be valid for SGL, use scratchpad */

  		skcipher_request_set_crypt(drbg->ctr_req, sg_in, sg_out,

  					   cryptlen, drbg->V);

  		ret = crypto_wait_req(crypto_skcipher_encrypt(drbg->ctr_req),
  					&drbg->ctr_wait);
  		if (ret)

  			goto out;

  
  		crypto_init_wait(&drbg->ctr_wait);

  		memcpy(outbuf, drbg->outscratchpad, cryptlen);

  		memzero_explicit(drbg->outscratchpad, cryptlen);

  		outlen -= cryptlen;

  		outbuf += cryptlen;

  	}

  	ret = 0;

  out:

  	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 drbg_cores definition to do this
   *
   * @cra_name kernel crypto API cra_name
   * @coreref reference to integer which is filled with the pointer to
   *  the applicable core
   * @pr reference for setting prediction resistance
   *
   * return: flags
   */
  static inline void drbg_convert_tfm_core(const char *cra_driver_name,
  					 int *coreref, bool *pr)
  {
  	int i = 0;
  	size_t start = 0;
  	int len = 0;
  
  	*pr = true;
  	/* disassemble the names */
  	if (!memcmp(cra_driver_name, "drbg_nopr_", 10)) {
  		start = 10;
  		*pr = false;
  	} else if (!memcmp(cra_driver_name, "drbg_pr_", 8)) {
  		start = 8;
  	} else {
  		return;
  	}
  
  	/* remove the first part */
  	len = strlen(cra_driver_name) - start;
  	for (i = 0; ARRAY_SIZE(drbg_cores) > i; i++) {
  		if (!memcmp(cra_driver_name + start, drbg_cores[i].cra_name,
  			    len)) {
  			*coreref = i;
  			return;
  		}
  	}
  }
  
  static int drbg_kcapi_init(struct crypto_tfm *tfm)
  {
  	struct drbg_state *drbg = crypto_tfm_ctx(tfm);

  	mutex_init(&drbg->drbg_mutex);

  
  	return 0;

  }
  
  static void drbg_kcapi_cleanup(struct crypto_tfm *tfm)
  {
  	drbg_uninstantiate(crypto_tfm_ctx(tfm));
  }
  
  /*
   * Generate random numbers invoked by the kernel crypto API:
   * The API of the kernel crypto API is extended as follows:
   *

   * src is additional input supplied to the RNG.
   * slen is the length of src.
   * dst is the output buffer where random data is to be stored.
   * dlen is the length of dst.

   */

  static int drbg_kcapi_random(struct crypto_rng *tfm,
  			     const u8 *src, unsigned int slen,
  			     u8 *dst, unsigned int dlen)

  {
  	struct drbg_state *drbg = crypto_rng_ctx(tfm);

  	struct drbg_string *addtl = NULL;
  	struct drbg_string string;
  
  	if (slen) {

  		/* linked list variable is now local to allow modification */

  		drbg_string_fill(&string, src, slen);
  		addtl = &string;

  	}

  
  	return drbg_generate_long(drbg, dst, dlen, addtl);

  }
  
  /*

   * Seed the DRBG invoked by the kernel crypto API

   */

  static int drbg_kcapi_seed(struct crypto_rng *tfm,
  			   const u8 *seed, unsigned int slen)

  {
  	struct drbg_state *drbg = crypto_rng_ctx(tfm);
  	struct crypto_tfm *tfm_base = crypto_rng_tfm(tfm);
  	bool pr = false;

  	struct drbg_string string;
  	struct drbg_string *seed_string = NULL;

  	int coreref = 0;

  	drbg_convert_tfm_core(crypto_tfm_alg_driver_name(tfm_base), &coreref,
  			      &pr);
  	if (0 < slen) {

  		drbg_string_fill(&string, seed, slen);
  		seed_string = &string;

  	}

  
  	return drbg_instantiate(drbg, seed_string, coreref, pr);

  }
  
  /***************************************************************
   * Kernel module: code to load the module
   ***************************************************************/
  
  /*
   * Tests as defined in 11.3.2 in addition to the cipher tests: testing
   * of the error handling.
   *
   * Note: testing of failing seed source as defined in 11.3.2 is not applicable
   * as seed source of get_random_bytes does not fail.
   *
   * Note 2: There is no sensible way of testing the reseed counter
   * enforcement, so skip it.
   */
  static inline int __init drbg_healthcheck_sanity(void)
  {

  	int len = 0;
  #define OUTBUFLEN 16
  	unsigned char buf[OUTBUFLEN];
  	struct drbg_state *drbg = NULL;
  	int ret = -EFAULT;
  	int rc = -EFAULT;
  	bool pr = false;
  	int coreref = 0;
  	struct drbg_string addtl;
  	size_t max_addtllen, max_request_bytes;
  
  	/* only perform test in FIPS mode */
  	if (!fips_enabled)
  		return 0;
  
  #ifdef CONFIG_CRYPTO_DRBG_CTR
  	drbg_convert_tfm_core("drbg_nopr_ctr_aes128", &coreref, &pr);

  #elif defined CONFIG_CRYPTO_DRBG_HASH

  	drbg_convert_tfm_core("drbg_nopr_sha256", &coreref, &pr);
  #else
  	drbg_convert_tfm_core("drbg_nopr_hmac_sha256", &coreref, &pr);
  #endif
  
  	drbg = kzalloc(sizeof(struct drbg_state), GFP_KERNEL);
  	if (!drbg)
  		return -ENOMEM;

  	mutex_init(&drbg->drbg_mutex);

  	drbg->core = &drbg_cores[coreref];
  	drbg->reseed_threshold = drbg_max_requests(drbg);

  	/*
  	 * if the following tests fail, it is likely that there is a buffer
  	 * overflow as buf is much smaller than the requested or provided
  	 * string lengths -- in case the error handling does not succeed
  	 * we may get an OOPS. And we want to get an OOPS as this is a
  	 * grave bug.
  	 */

  	max_addtllen = drbg_max_addtl(drbg);
  	max_request_bytes = drbg_max_request_bytes(drbg);
  	drbg_string_fill(&addtl, buf, max_addtllen + 1);
  	/* overflow addtllen with additonal info string */
  	len = drbg_generate(drbg, buf, OUTBUFLEN, &addtl);
  	BUG_ON(0 < len);
  	/* overflow max_bits */
  	len = drbg_generate(drbg, buf, (max_request_bytes + 1), NULL);
  	BUG_ON(0 < len);

  
  	/* overflow max addtllen with personalization string */

  	ret = drbg_seed(drbg, &addtl, false);

  	BUG_ON(0 == ret);

  	/* all tests passed */
  	rc = 0;
  
  	pr_devel("DRBG: Sanity tests for failure code paths successfully "
  		 "completed
  ");

  	kfree(drbg);

  	return rc;

  }

  static struct rng_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 drbg_cores[] is used.
   */

  static inline void __init drbg_fill_array(struct rng_alg *alg,

  					  const struct drbg_core *core, int pr)
  {
  	int pos = 0;

  	static int priority = 200;

  	memcpy(alg->base.cra_name, "stdrng", 6);

  	if (pr) {

  		memcpy(alg->base.cra_driver_name, "drbg_pr_", 8);

  		pos = 8;
  	} else {

  		memcpy(alg->base.cra_driver_name, "drbg_nopr_", 10);

  		pos = 10;
  	}

  	memcpy(alg->base.cra_driver_name + pos, core->cra_name,

  	       strlen(core->cra_name));

  	alg->base.cra_priority = priority;

  	priority++;
  	/*
  	 * If FIPS mode enabled, the selected DRBG shall have the
  	 * highest cra_priority over other stdrng instances to ensure
  	 * it is selected.
  	 */
  	if (fips_enabled)

  		alg->base.cra_priority += 200;
  
  	alg->base.cra_ctxsize 	= sizeof(struct drbg_state);
  	alg->base.cra_module	= THIS_MODULE;
  	alg->base.cra_init	= drbg_kcapi_init;
  	alg->base.cra_exit	= drbg_kcapi_cleanup;
  	alg->generate		= drbg_kcapi_random;
  	alg->seed		= drbg_kcapi_seed;
  	alg->set_ent		= drbg_kcapi_set_entropy;
  	alg->seedsize		= 0;

  }
  
  static int __init drbg_init(void)
  {
  	unsigned int i = 0; /* pointer to drbg_algs */
  	unsigned int j = 0; /* pointer to drbg_cores */

  	int ret;

  
  	ret = drbg_healthcheck_sanity();
  	if (ret)
  		return ret;
  
  	if (ARRAY_SIZE(drbg_cores) * 2 > ARRAY_SIZE(drbg_algs)) {
  		pr_info("DRBG: Cannot register all DRBG types"

  			"(slots needed: %zu, slots available: %zu)
  ",

  			ARRAY_SIZE(drbg_cores) * 2, ARRAY_SIZE(drbg_algs));

  		return -EFAULT;

  	}
  
  	/*
  	 * each DRBG definition can be used with PR and without PR, thus
  	 * we instantiate each DRBG in drbg_cores[] twice.
  	 *
  	 * As the order of placing them into the drbg_algs array matters
  	 * (the later DRBGs receive a higher cra_priority) we register the
  	 * prediction resistance DRBGs first as the should not be too
  	 * interesting.
  	 */
  	for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
  		drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 1);
  	for (j = 0; ARRAY_SIZE(drbg_cores) > j; j++, i++)
  		drbg_fill_array(&drbg_algs[i], &drbg_cores[j], 0);

  	return crypto_register_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));

  }

  static void __exit drbg_exit(void)

  {

  	crypto_unregister_rngs(drbg_algs, (ARRAY_SIZE(drbg_cores) * 2));

  }

  subsys_initcall(drbg_init);

  module_exit(drbg_exit);

  #ifndef CRYPTO_DRBG_HASH_STRING
  #define CRYPTO_DRBG_HASH_STRING ""

  #endif

  #ifndef CRYPTO_DRBG_HMAC_STRING
  #define CRYPTO_DRBG_HMAC_STRING ""

  #endif

  #ifndef CRYPTO_DRBG_CTR_STRING
  #define CRYPTO_DRBG_CTR_STRING ""

  #endif

  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Stephan Mueller <smueller@chronox.de>");
  MODULE_DESCRIPTION("NIST SP800-90A Deterministic Random Bit Generator (DRBG) "
  		   "using following cores: "
  		   CRYPTO_DRBG_HASH_STRING
  		   CRYPTO_DRBG_HMAC_STRING
  		   CRYPTO_DRBG_CTR_STRING);

  MODULE_ALIAS_CRYPTO("stdrng");

  MODULE_IMPORT_NS(CRYPTO_INTERNAL);