drbg.c 57 KB
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/*
 * 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>
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#include <linux/kernel.h>
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/***************************************************************
 * 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",
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		.backend_cra_name = "aes",
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	}, {
		.flags = DRBG_CTR | DRBG_STRENGTH192,
		.statelen = 40, /* 320 bits as defined in 10.2.1 */
		.blocklen_bytes = 16,
		.cra_name = "ctr_aes192",
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		.backend_cra_name = "aes",
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	}, {
		.flags = DRBG_CTR | DRBG_STRENGTH256,
		.statelen = 48, /* 384 bits as defined in 10.2.1 */
		.blocklen_bytes = 16,
		.cra_name = "ctr_aes256",
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		.backend_cra_name = "aes",
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	},
#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
	{
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		.flags = DRBG_HMAC | DRBG_STRENGTH128,
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		.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 = 64, /* block length of cipher */
		.blocklen_bytes = 64,
		.cra_name = "hmac_sha512",
		.backend_cra_name = "hmac(sha512)",
	}, {
		.flags = DRBG_HMAC | DRBG_STRENGTH256,
		.statelen = 32, /* block length of cipher */
		.blocklen_bytes = 32,
		.cra_name = "hmac_sha256",
		.backend_cra_name = "hmac(sha256)",
	},
#endif /* CONFIG_CRYPTO_DRBG_HMAC */
};

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static int drbg_uninstantiate(struct drbg_state *drbg);

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/******************************************************************
 * 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;
	}
}

/*
 * Convert an integer into a byte representation of this integer.
 * The byte representation is big-endian
 *
 * @val value to be converted
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 * @buf buffer holding the converted integer -- caller must ensure that
 *      buffer size is at least 32 bit
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 */
#if (defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR))
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static inline void drbg_cpu_to_be32(__u32 val, unsigned char *buf)
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{
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	struct s {
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		__be32 conv;
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	};
	struct s *conversion = (struct s *) buf;
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	conversion->conv = cpu_to_be32(val);
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}
#endif /* defined(CONFIG_CRYPTO_DRBG_HASH) || defined(CONFIG_CRYPTO_DRBG_CTR) */

/******************************************************************
 * CTR DRBG callback functions
 ******************************************************************/

#ifdef CONFIG_CRYPTO_DRBG_CTR
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#define CRYPTO_DRBG_CTR_STRING "CTR "
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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");
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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);
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static int drbg_init_sym_kernel(struct drbg_state *drbg);
static int drbg_fini_sym_kernel(struct drbg_state *drbg);
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static int drbg_kcapi_sym_ctr(struct drbg_state *drbg, u8 *outbuf, u32 outlen);
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/* 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,
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			struct list_head *in)
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{
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	int ret = 0;
	struct drbg_string *curr = NULL;
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	struct drbg_string data;
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	short cnt = 0;
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	drbg_string_fill(&data, out, drbg_blocklen(drbg));

	/* 10.4.3 step 2 / 4 */
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	drbg_kcapi_symsetkey(drbg, key);
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	list_for_each_entry(curr, in, list) {
		const unsigned char *pos = curr->buf;
		size_t len = curr->len;
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		/* 10.4.3 step 4.1 */
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		while (len) {
			/* 10.4.3 step 4.2 */
			if (drbg_blocklen(drbg) == cnt) {
				cnt = 0;
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				ret = drbg_kcapi_sym(drbg, out, &data);
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				if (ret)
					return ret;
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			}
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			out[cnt] ^= *pos;
			pos++;
			cnt++;
			len--;
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		}
	}
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	/* 10.4.3 step 4.2 for last block */
	if (cnt)
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		ret = drbg_kcapi_sym(drbg, out, &data);
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	return ret;
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}

/*
 * 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)
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 *		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.
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 */

/* 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,
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		       struct list_head *seedlist)
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{
	int ret = -EFAULT;
	unsigned char L_N[8];
	/* S3 is input */
	struct drbg_string S1, S2, S4, cipherin;
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	LIST_HEAD(bcc_list);
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	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;
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	struct drbg_string *seed = NULL;
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	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 */
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	list_for_each_entry(seed, seedlist, list)
		inputlen += seed->len;
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	drbg_cpu_to_be32(inputlen, &L_N[0]);
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	/* 10.4.2 step 3 */
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	drbg_cpu_to_be32(bytes_to_return, &L_N[4]);
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	/* 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));
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	list_add_tail(&S1.list, &bcc_list);
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	drbg_string_fill(&S2, L_N, sizeof(L_N));
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	list_add_tail(&S2.list, &bcc_list);
	list_splice_tail(seedlist, &bcc_list);
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	drbg_string_fill(&S4, pad, padlen);
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	list_add_tail(&S4.list, &bcc_list);
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	/* 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
		 */
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		drbg_cpu_to_be32(i, iv);
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		/* 10.4.2 step 9.2 -- BCC and concatenation with temp */
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		ret = drbg_ctr_bcc(drbg, temp + templen, K, &bcc_list);
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		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 */
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	drbg_kcapi_symsetkey(drbg, temp);
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	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
		 */
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		ret = drbg_kcapi_sym(drbg, X, &cipherin);
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		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:
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	memset(iv, 0, drbg_blocklen(drbg));
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	memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
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	memset(pad, 0, drbg_blocklen(drbg));
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	return ret;
}

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/*
 * 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.
 */
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static int drbg_ctr_update(struct drbg_state *drbg, struct list_head *seed,
			   int reseed)
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{
	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);
	unsigned char *temp_p, *df_data_p; /* pointer to iterate over buffers */
	unsigned int len = 0;

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	if (3 > reseed)
		memset(df_data, 0, drbg_statelen(drbg));
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	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));
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		if (ret)
			goto out;
	}

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	/* 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);
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		if (ret)
			goto out;
	}

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	ret = drbg_kcapi_sym_ctr(drbg, temp, drbg_statelen(drbg));
	if (ret)
		return ret;

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	/* 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));
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	ret = crypto_skcipher_setkey(drbg->ctr_handle, drbg->C,
				     drbg_keylen(drbg));
	if (ret)
		goto out;
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	/* 10.2.1.2 step 6 */
	memcpy(drbg->V, temp + drbg_keylen(drbg), drbg_blocklen(drbg));
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	/* See above: increment counter by one to compensate timing of CTR op */
	crypto_inc(drbg->V, drbg_blocklen(drbg));
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	ret = 0;

out:
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	memset(temp, 0, drbg_statelen(drbg) + drbg_blocklen(drbg));
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	if (2 != reseed)
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		memset(df_data, 0, drbg_statelen(drbg));
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	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,
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			     struct list_head *addtl)
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{
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	int ret;
	int len = min_t(int, buflen, INT_MAX);
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	/* 10.2.1.5.2 step 2 */
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	if (addtl && !list_empty(addtl)) {
		ret = drbg_ctr_update(drbg, addtl, 2);
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		if (ret)
			return 0;
	}

	/* 10.2.1.5.2 step 4.1 */
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	ret = drbg_kcapi_sym_ctr(drbg, buf, len);
	if (ret)
		return ret;
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	/* 10.2.1.5.2 step 6 */
	ret = drbg_ctr_update(drbg, NULL, 3);
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	if (ret)
		len = ret;

	return len;
}

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static const struct drbg_state_ops drbg_ctr_ops = {
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	.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)
589 590 591 592
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);
593 594 595 596 597
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
598
#define CRYPTO_DRBG_HMAC_STRING "HMAC "
599 600 601 602 603 604 605 606
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");
607

608
/* update function of HMAC DRBG as defined in 10.1.2.2 */
609 610
static int drbg_hmac_update(struct drbg_state *drbg, struct list_head *seed,
			    int reseed)
611 612 613
{
	int ret = -EFAULT;
	int i = 0;
614 615 616
	struct drbg_string seed1, seed2, vdata;
	LIST_HEAD(seedlist);
	LIST_HEAD(vdatalist);
617

618
	if (!reseed) {
619
		/* 10.1.2.3 step 2 -- memset(0) of C is implicit with kzalloc */
620
		memset(drbg->V, 1, drbg_statelen(drbg));
621 622
		drbg_kcapi_hmacsetkey(drbg, drbg->C);
	}
623 624

	drbg_string_fill(&seed1, drbg->V, drbg_statelen(drbg));
625
	list_add_tail(&seed1.list, &seedlist);
626 627
	/* buffer of seed2 will be filled in for loop below with one byte */
	drbg_string_fill(&seed2, NULL, 1);
628
	list_add_tail(&seed2.list, &seedlist);
629
	/* input data of seed is allowed to be NULL at this point */
630 631
	if (seed)
		list_splice_tail(seed, &seedlist);
632

633 634
	drbg_string_fill(&vdata, drbg->V, drbg_statelen(drbg));
	list_add_tail(&vdata.list, &vdatalist);
635 636 637 638 639 640 641
	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;
642
		ret = drbg_kcapi_hash(drbg, drbg->C, &seedlist);
643 644
		if (ret)
			return ret;
645
		drbg_kcapi_hmacsetkey(drbg, drbg->C);
646 647

		/* 10.1.2.2 step 2 and 5 -- HMAC for V */
648
		ret = drbg_kcapi_hash(drbg, drbg->V, &vdatalist);
649 650 651 652
		if (ret)
			return ret;

		/* 10.1.2.2 step 3 */
653
		if (!seed)
654 655 656 657 658 659 660 661 662 663
			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,
664
			      struct list_head *addtl)
665 666 667 668
{
	int len = 0;
	int ret = 0;
	struct drbg_string data;
669
	LIST_HEAD(datalist);
670 671

	/* 10.1.2.5 step 2 */
672 673
	if (addtl && !list_empty(addtl)) {
		ret = drbg_hmac_update(drbg, addtl, 1);
674 675 676 677 678
		if (ret)
			return ret;
	}

	drbg_string_fill(&data, drbg->V, drbg_statelen(drbg));
679
	list_add_tail(&data.list, &datalist);
680 681 682
	while (len < buflen) {
		unsigned int outlen = 0;
		/* 10.1.2.5 step 4.1 */
683
		ret = drbg_kcapi_hash(drbg, drbg->V, &datalist);
684 685 686 687 688 689 690 691 692 693 694
		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 */
695 696 697
	if (addtl && !list_empty(addtl))
		ret = drbg_hmac_update(drbg, addtl, 1);
	else
698
		ret = drbg_hmac_update(drbg, NULL, 1);
699 700 701 702 703 704
	if (ret)
		return ret;

	return len;
}

705
static const struct drbg_state_ops drbg_hmac_ops = {
706 707 708 709 710 711 712 713 714 715 716 717
	.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
718
#define CRYPTO_DRBG_HASH_STRING "HASH "
719 720 721 722 723 724 725 726
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");
727

728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759
/*
 * 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--;
	}
}

760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777
/*
 * 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,
778
			struct list_head *entropylist)
779 780 781 782 783
{
	int ret = 0;
	size_t len = 0;
	unsigned char input[5];
	unsigned char *tmp = drbg->scratchpad + drbg_statelen(drbg);
784
	struct drbg_string data;
785 786 787

	/* 10.4.1 step 3 */
	input[0] = 1;
788
	drbg_cpu_to_be32((outlen * 8), &input[1]);
789 790

	/* 10.4.1 step 4.1 -- concatenation of data for input into hash */
791 792
	drbg_string_fill(&data, input, 5);
	list_add(&data.list, entropylist);
793 794 795 796 797

	/* 10.4.1 step 4 */
	while (len < outlen) {
		short blocklen = 0;
		/* 10.4.1 step 4.1 */
798
		ret = drbg_kcapi_hash(drbg, tmp, entropylist);
799 800 801 802 803 804 805 806 807 808 809
		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:
810
	memset(tmp, 0, drbg_blocklen(drbg));
811 812 813 814
	return ret;
}

/* update function for Hash DRBG as defined in 10.1.1.2 / 10.1.1.3 */
815
static int drbg_hash_update(struct drbg_state *drbg, struct list_head *seed,
816 817 818 819
			    int reseed)
{
	int ret = 0;
	struct drbg_string data1, data2;
820 821
	LIST_HEAD(datalist);
	LIST_HEAD(datalist2);
822 823 824 825 826 827 828 829 830 831
	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);
832
		list_add_tail(&data1.list, &datalist);
833
		drbg_string_fill(&data2, V, drbg_statelen(drbg));
834
		list_add_tail(&data2.list, &datalist);
835
	}
836
	list_splice_tail(seed, &datalist);
837 838

	/* 10.1.1.2 / 10.1.1.3 step 2 and 3 */
839
	ret = drbg_hash_df(drbg, drbg->V, drbg_statelen(drbg), &datalist);
840 841 842 843 844 845
	if (ret)
		goto out;

	/* 10.1.1.2 / 10.1.1.3 step 4  */
	prefix = DRBG_PREFIX0;
	drbg_string_fill(&data1, &prefix, 1);
846
	list_add_tail(&data1.list, &datalist2);
847
	drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
848
	list_add_tail(&data2.list, &datalist2);
849
	/* 10.1.1.2 / 10.1.1.3 step 4 */
850
	ret = drbg_hash_df(drbg, drbg->C, drbg_statelen(drbg), &datalist2);
851 852

out:
853
	memset(drbg->scratchpad, 0, drbg_statelen(drbg));
854 855 856 857 858
	return ret;
}

/* processing of additional information string for Hash DRBG */
static int drbg_hash_process_addtl(struct drbg_state *drbg,
859
				   struct list_head *addtl)
860 861 862
{
	int ret = 0;
	struct drbg_string data1, data2;
863
	LIST_HEAD(datalist);
864 865 866
	unsigned char prefix = DRBG_PREFIX2;

	/* 10.1.1.4 step 2 */
867
	if (!addtl || list_empty(addtl))
868 869 870 871 872
		return 0;

	/* 10.1.1.4 step 2a */
	drbg_string_fill(&data1, &prefix, 1);
	drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
873 874
	list_add_tail(&data1.list, &datalist);
	list_add_tail(&data2.list, &datalist);
875
	list_splice_tail(addtl, &datalist);
876
	ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
877 878 879 880 881 882 883 884
	if (ret)
		goto out;

	/* 10.1.1.4 step 2b */
	drbg_add_buf(drbg->V, drbg_statelen(drbg),
		     drbg->scratchpad, drbg_blocklen(drbg));

out:
885
	memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
886 887 888 889 890 891 892 893 894 895 896 897 898
	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;
899
	LIST_HEAD(datalist);
900 901 902 903 904

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

	drbg_string_fill(&data, src, drbg_statelen(drbg));
905
	list_add_tail(&data.list, &datalist);
906 907 908
	while (len < buflen) {
		unsigned int outlen = 0;
		/* 10.1.1.4 step hashgen 4.1 */
909
		ret = drbg_kcapi_hash(drbg, dst, &datalist);
910 911 912 913 914 915 916 917 918 919 920
		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)
921
			crypto_inc(src, drbg_statelen(drbg));
922 923 924
	}

out:
925
	memset(drbg->scratchpad, 0,
926 927 928 929 930 931 932
	       (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,
933
			      struct list_head *addtl)
934 935 936
{
	int len = 0;
	int ret = 0;
937 938
	union {
		unsigned char req[8];
939
		__be64 req_int;
940
	} u;
941 942
	unsigned char prefix = DRBG_PREFIX3;
	struct drbg_string data1, data2;
943
	LIST_HEAD(datalist);
944 945 946 947 948 949 950 951 952 953 954

	/* 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);
955
	list_add_tail(&data1.list, &datalist);
956
	drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
957
	list_add_tail(&data2.list, &datalist);
958
	ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
959 960 961 962 963 964 965 966 967 968
	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));
969 970
	u.req_int = cpu_to_be64(drbg->reseed_ctr);
	drbg_add_buf(drbg->V, drbg_statelen(drbg), u.req, 8);
971 972

out:
973
	memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
974 975 976 977 978 979 980
	return len;
}

/*
 * scratchpad usage: as update and generate are used isolated, both
 * can use the scratchpad
 */
981
static const struct drbg_state_ops drbg_hash_ops = {
982 983 984 985 986 987 988 989 990 991 992
	.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
 ******************************************************************/

993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007
static inline int __drbg_seed(struct drbg_state *drbg, struct list_head *seed,
			      int reseed)
{
	int ret = drbg->d_ops->update(drbg, seed, reseed);

	if (ret)
		return ret;

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

	return ret;
}

1008 1009 1010 1011 1012 1013
static void drbg_async_seed(struct work_struct *work)
{
	struct drbg_string data;
	LIST_HEAD(seedlist);
	struct drbg_state *drbg = container_of(work, struct drbg_state,
					       seed_work);
1014 1015
	unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
	unsigned char entropy[32];
1016

1017 1018 1019
	BUG_ON(!entropylen);
	BUG_ON(entropylen > sizeof(entropy));
	get_random_bytes(entropy, entropylen);
1020

1021
	drbg_string_fill(&data, entropy, entropylen);
1022
	list_add_tail(&data.list, &seedlist);
1023

1024
	mutex_lock(&drbg->drbg_mutex);
1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036

	/* If nonblocking pool is initialized, deactivate Jitter RNG */
	crypto_free_rng(drbg->jent);
	drbg->jent = NULL;

	/* Set seeded to false so that if __drbg_seed fails the
	 * next generate call will trigger a reseed.
	 */
	drbg->seeded = false;

	__drbg_seed(drbg, &seedlist, true);

1037 1038 1039
	if (drbg->seeded)
		drbg->reseed_threshold = drbg_max_requests(drbg);

1040
	mutex_unlock(&drbg->drbg_mutex);
1041 1042

	memzero_explicit(entropy, entropylen);
1043 1044
}

1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058
/*
 * 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)
{
1059 1060 1061
	int ret;
	unsigned char entropy[((32 + 16) * 2)];
	unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
1062
	struct drbg_string data1;
1063
	LIST_HEAD(seedlist);
1064 1065 1066

	/* 9.1 / 9.2 / 9.3.1 step 3 */
	if (pers && pers->len > (drbg_max_addtl(drbg))) {
1067
		pr_devel("DRBG: personalization string too long %zu\n",
1068 1069 1070 1071
			 pers->len);
		return -EINVAL;
	}

1072 1073 1074
	if (list_empty(&drbg->test_data.list)) {
		drbg_string_fill(&data1, drbg->test_data.buf,
				 drbg->test_data.len);
1075 1076
		pr_devel("DRBG: using test entropy\n");
	} else {
1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089
		/*
		 * 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));

1090
		/* Get seed from in-kernel /dev/urandom */
1091 1092 1093 1094 1095 1096
		get_random_bytes(entropy, entropylen);

		if (!drbg->jent) {
			drbg_string_fill(&data1, entropy, entropylen);
			pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
				 entropylen);
1097
		} else {
1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109
			/* Get seed from Jitter RNG */
			ret = crypto_rng_get_bytes(drbg->jent,
						   entropy + entropylen,
						   entropylen);
			if (ret) {
				pr_devel("DRBG: jent failed with %d\n", ret);
				return ret;
			}

			drbg_string_fill(&data1, entropy, entropylen * 2);
			pr_devel("DRBG: (re)seeding with %u bytes of entropy\n",
				 entropylen * 2);
1110
		}
1111
	}
1112
	list_add_tail(&data1.list, &seedlist);
1113 1114 1115 1116 1117 1118

	/*
	 * 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
	 */
1119 1120
	if (pers && pers->buf && 0 < pers->len) {
		list_add_tail(&pers->list, &seedlist);
1121 1122 1123
		pr_devel("DRBG: using personalization string\n");
	}

1124 1125 1126 1127 1128
	if (!reseed) {
		memset(drbg->V, 0, drbg_statelen(drbg));
		memset(drbg->C, 0, drbg_statelen(drbg));
	}

1129 1130
	ret = __drbg_seed(drbg, &seedlist, reseed);

1131
	memzero_explicit(entropy, entropylen * 2);
1132

1133 1134 1135 1136 1137 1138 1139 1140
	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;
1141
	kzfree(drbg->V);
1142
	drbg->V = NULL;
1143
	kzfree(drbg->C);
1144
	drbg->C = NULL;
1145
	kzfree(drbg->scratchpad);
1146 1147
	drbg->scratchpad = NULL;
	drbg->reseed_ctr = 0;
1148 1149
	drbg->d_ops = NULL;
	drbg->core = NULL;
1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160
}

/*
 * 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;

1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181
	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;
	}

1182
	drbg->V = kmalloc(drbg_statelen(drbg), GFP_KERNEL);
1183 1184
	if (!drbg->V)
		goto err;
1185
	drbg->C = kmalloc(drbg_statelen(drbg), GFP_KERNEL);
1186 1187 1188 1189 1190 1191 1192 1193 1194 1195
	if (!drbg->C)
		goto err;
	/* 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 */
1196
			  drbg_statelen(drbg) + drbg_blocklen(drbg); /* temp */
1197 1198 1199 1200 1201 1202 1203 1204
	else
		sb_size = drbg_statelen(drbg) + drbg_blocklen(drbg);

	if (0 < sb_size) {
		drbg->scratchpad = kzalloc(sb_size, GFP_KERNEL);
		if (!drbg->scratchpad)
			goto err;
	}
1205

1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230
	return 0;

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.
 *
1231
 * return: 0 when all bytes are generated; < 0 in case of an error
1232 1233 1234 1235 1236 1237
 */
static int drbg_generate(struct drbg_state *drbg,
			 unsigned char *buf, unsigned int buflen,
			 struct drbg_string *addtl)
{
	int len = 0;
1238
	LIST_HEAD(addtllist);
1239

1240 1241 1242 1243
	if (!drbg->core) {
		pr_devel("DRBG: not yet seeded\n");
		return -EINVAL;
	}
1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254
	if (0 == buflen || !buf) {
		pr_devel("DRBG: no output buffer provided\n");
		return -EINVAL;
	}
	if (addtl && NULL == addtl->buf && 0 < addtl->len) {
		pr_devel("DRBG: wrong format of additional information\n");
		return -EINVAL;
	}

	/* 9.3.1 step 2 */
	len = -EINVAL;
1255
	if (buflen > (drbg_max_request_bytes(drbg))) {
1256 1257 1258 1259 1260 1261 1262 1263
		pr_devel("DRBG: requested random numbers too large %u\n",
			 buflen);
		goto err;
	}

	/* 9.3.1 step 3 is implicit with the chosen DRBG */

	/* 9.3.1 step 4 */
1264
	if (addtl && addtl->len > (drbg_max_addtl(drbg))) {
1265 1266 1267 1268 1269 1270 1271 1272 1273 1274
		pr_devel("DRBG: additional information string too long %zu\n",
			 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.
	 */
1275
	if (drbg->reseed_threshold < drbg->reseed_ctr)
1276
		drbg->seeded = false;
1277

1278
	if (drbg->pr || !drbg->seeded) {
1279 1280 1281 1282 1283
		pr_devel("DRBG: reseeding before generation (prediction "
			 "resistance: %s, state %s)\n",
			 drbg->pr ? "true" : "false",
			 drbg->seeded ? "seeded" : "unseeded");
		/* 9.3.1 steps 7.1 through 7.3 */
1284
		len = drbg_seed(drbg, addtl, true);
1285 1286 1287 1288 1289
		if (len)
			goto err;
		/* 9.3.1 step 7.4 */
		addtl = NULL;
	}
1290 1291 1292

	if (addtl && 0 < addtl->len)
		list_add_tail(&addtl->list, &addtllist);
1293
	/* 9.3.1 step 8 and 10 */
1294
	len = drbg->d_ops->generate(drbg, buf, buflen, &addtllist);
1295 1296

	/* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */
1297
	drbg->reseed_ctr++;
1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316
	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
1317
	if (drbg->reseed_ctr && !(drbg->reseed_ctr % 4096)) {
1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342
		int err = 0;
		pr_devel("DRBG: start to perform self test\n");
		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\n");
			/*
			 * 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\n");
		}
	}
#endif

1343 1344 1345 1346 1347
	/*
	 * All operations were successful, return 0 as mandated by
	 * the kernel crypto API interface.
	 */
	len = 0;
1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363
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)
{
1364
	unsigned int len = 0;
1365 1366
	unsigned int slice = 0;
	do {
1367
		int err = 0;
1368 1369 1370
		unsigned int chunk = 0;
		slice = ((buflen - len) / drbg_max_request_bytes(drbg));
		chunk = slice ? drbg_max_request_bytes(drbg) : (buflen - len);
1371
		mutex_lock(&drbg->drbg_mutex);
1372
		err = drbg_generate(drbg, buf + len, chunk, addtl);
1373
		mutex_unlock(&drbg->drbg_mutex);
1374 1375 1376
		if (0 > err)
			return err;
		len += chunk;
1377
	} while (slice > 0 && (len < buflen));
1378
	return 0;
1379 1380
}

1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418
static void drbg_schedule_async_seed(struct random_ready_callback *rdy)
{
	struct drbg_state *drbg = container_of(rdy, struct drbg_state,
					       random_ready);

	schedule_work(&drbg->seed_work);
}

static int drbg_prepare_hrng(struct drbg_state *drbg)
{
	int err;

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

	INIT_WORK(&drbg->seed_work, drbg_async_seed);

	drbg->random_ready.owner = THIS_MODULE;
	drbg->random_ready.func = drbg_schedule_async_seed;

	err = add_random_ready_callback(&drbg->random_ready);

	switch (err) {
	case 0:
		break;

	case -EALREADY:
		err = 0;
		/* fall through */

	default:
		drbg->random_ready.func = NULL;
		return err;
	}

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

1419 1420 1421 1422 1423 1424
	/*
	 * Require frequent reseeds until the seed source is fully
	 * initialized.
	 */
	drbg->reseed_threshold = 50;

1425 1426 1427
	return err;
}

1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447
/*
 * 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)
{
1448 1449
	int ret;
	bool reseed = true;
1450 1451 1452

	pr_devel("DRBG: Initializing DRBG core %d with prediction resistance "
		 "%s\n", coreref, pr ? "enabled" : "disabled");
1453
	mutex_lock(&drbg->drbg_mutex);
1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464

	/* 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 */

1465 1466 1467 1468
	if (!drbg->core) {
		drbg->core = &drbg_cores[coreref];
		drbg->pr = pr;
		drbg->seeded = false;
1469
		drbg->reseed_threshold = drbg_max_requests(drbg);
1470

1471 1472 1473 1474 1475 1476 1477 1478
		ret = drbg_alloc_state(drbg);
		if (ret)
			goto unlock;

		ret = -EFAULT;
		if (drbg->d_ops->crypto_init(drbg))
			goto err;

1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490
		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\n");
		}

1491 1492 1493 1494 1495
		reseed = false;
	}

	ret = drbg_seed(drbg, pers, reseed);

1496 1497
	if (ret && !reseed)
		goto free_everything;
1498

1499
	mutex_unlock(&drbg->drbg_mutex);
1500
	return ret;
1501 1502 1503

err:
	drbg_dealloc_state(drbg);
1504 1505
unlock:
	mutex_unlock(&drbg->drbg_mutex);
1506
	return ret;
1507 1508 1509 1510 1511

free_everything:
	mutex_unlock(&drbg->drbg_mutex);
	drbg_uninstantiate(drbg);
	return ret;
1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524
}

/*
 * 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)
{
1525 1526 1527 1528 1529 1530 1531
	if (drbg->random_ready.func) {
		del_random_ready_callback(&drbg->random_ready);
		cancel_work_sync(&drbg->seed_work);
		crypto_free_rng(drbg->jent);
		drbg->jent = NULL;
	}

1532 1533
	if (drbg->d_ops)
		drbg->d_ops->crypto_fini(drbg);
1534 1535 1536 1537 1538 1539 1540 1541 1542
	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
1543 1544
 * @data test data
 * @len test data length
1545
 */
1546 1547
static void drbg_kcapi_set_entropy(struct crypto_rng *tfm,
				   const u8 *data, unsigned int len)
1548
{
1549 1550 1551 1552
	struct drbg_state *drbg = crypto_rng_ctx(tfm);

	mutex_lock(&drbg->drbg_mutex);
	drbg_string_fill(&drbg->test_data, data, len);
1553
	mutex_unlock(&drbg->drbg_mutex);
1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572
}

/***************************************************************
 * 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)) {