drbg.c 54.5 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 int drbg_kcapi_sym(struct drbg_state *drbg, const unsigned char *key,
			  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);

/* 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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	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;
				ret = drbg_kcapi_sym(drbg, key, out, &data);
				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)
		ret = drbg_kcapi_sym(drbg, key, out, &data);

	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 */
	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, temp, X, &cipherin);
		if (ret)
			goto out;
		blocklen = (drbg_blocklen(drbg) <
				(bytes_to_return - generated_len)) ?
			    drbg_blocklen(drbg) :
				(bytes_to_return - generated_len);
		/* 10.4.2 step 13.2 and 14 */
		memcpy(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;
	struct drbg_string cipherin;

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	if (3 > reseed)
		memset(df_data, 0, drbg_statelen(drbg));
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	/* 10.2.1.3.2 step 2 and 10.2.1.4.2 step 2 */
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	if (seed) {
		ret = drbg_ctr_df(drbg, df_data, drbg_statelen(drbg), seed);
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		if (ret)
			goto out;
	}

	drbg_string_fill(&cipherin, drbg->V, drbg_blocklen(drbg));
	/*
	 * 10.2.1.3.2 steps 2 and 3 are already covered as the allocation
	 * zeroizes all memory during initialization
	 */
	while (len < (drbg_statelen(drbg))) {
		/* 10.2.1.2 step 2.1 */
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		crypto_inc(drbg->V, drbg_blocklen(drbg));
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		/*
		 * 10.2.1.2 step 2.2 */
		ret = drbg_kcapi_sym(drbg, drbg->C, temp + len, &cipherin);
		if (ret)
			goto out;
		/* 10.2.1.2 step 2.3 and 3 */
		len += drbg_blocklen(drbg);
	}

	/* 10.2.1.2 step 4 */
	temp_p = temp;
	df_data_p = df_data;
	for (len = 0; len < drbg_statelen(drbg); len++) {
		*temp_p ^= *df_data_p;
		df_data_p++; temp_p++;
	}

	/* 10.2.1.2 step 5 */
	memcpy(drbg->C, temp, drbg_keylen(drbg));
	/* 10.2.1.2 step 6 */
	memcpy(drbg->V, temp + drbg_keylen(drbg), drbg_blocklen(drbg));
	ret = 0;

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

	/* 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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	crypto_inc(drbg->V, drbg_blocklen(drbg));
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	drbg_string_fill(&data, drbg->V, drbg_blocklen(drbg));
	while (len < buflen) {
		int outlen = 0;
		/* 10.2.1.5.2 step 4.2 */
		ret = drbg_kcapi_sym(drbg, drbg->C, drbg->scratchpad, &data);
		if (ret) {
			len = ret;
			goto out;
		}
		outlen = (drbg_blocklen(drbg) < (buflen - len)) ?
			  drbg_blocklen(drbg) : (buflen - len);
		/* 10.2.1.5.2 step 4.3 */
		memcpy(buf + len, drbg->scratchpad, outlen);
		len += outlen;
		/* 10.2.1.5.2 step 6 */
		if (len < buflen)
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			crypto_inc(drbg->V, drbg_blocklen(drbg));
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	}

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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;

out:
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	memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
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	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)
595 596 597 598
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);
599 600 601 602 603
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
604
#define CRYPTO_DRBG_HMAC_STRING "HMAC "
605 606 607 608 609 610 611 612
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");
613

614
/* update function of HMAC DRBG as defined in 10.1.2.2 */
615 616
static int drbg_hmac_update(struct drbg_state *drbg, struct list_head *seed,
			    int reseed)
617 618 619
{
	int ret = -EFAULT;
	int i = 0;
620 621 622
	struct drbg_string seed1, seed2, vdata;
	LIST_HEAD(seedlist);
	LIST_HEAD(vdatalist);
623

624
	if (!reseed) {
625
		/* 10.1.2.3 step 2 -- memset(0) of C is implicit with kzalloc */
626
		memset(drbg->V, 1, drbg_statelen(drbg));
627 628
		drbg_kcapi_hmacsetkey(drbg, drbg->C);
	}
629 630

	drbg_string_fill(&seed1, drbg->V, drbg_statelen(drbg));
631
	list_add_tail(&seed1.list, &seedlist);
632 633
	/* buffer of seed2 will be filled in for loop below with one byte */
	drbg_string_fill(&seed2, NULL, 1);
634
	list_add_tail(&seed2.list, &seedlist);
635
	/* input data of seed is allowed to be NULL at this point */
636 637
	if (seed)
		list_splice_tail(seed, &seedlist);
638

639 640
	drbg_string_fill(&vdata, drbg->V, drbg_statelen(drbg));
	list_add_tail(&vdata.list, &vdatalist);
641 642 643 644 645 646 647
	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;
648
		ret = drbg_kcapi_hash(drbg, drbg->C, &seedlist);
649 650
		if (ret)
			return ret;
651
		drbg_kcapi_hmacsetkey(drbg, drbg->C);
652 653

		/* 10.1.2.2 step 2 and 5 -- HMAC for V */
654
		ret = drbg_kcapi_hash(drbg, drbg->V, &vdatalist);
655 656 657 658
		if (ret)
			return ret;

		/* 10.1.2.2 step 3 */
659
		if (!seed)
660 661 662 663 664 665 666 667 668 669
			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,
670
			      struct list_head *addtl)
671 672 673 674
{
	int len = 0;
	int ret = 0;
	struct drbg_string data;
675
	LIST_HEAD(datalist);
676 677

	/* 10.1.2.5 step 2 */
678 679
	if (addtl && !list_empty(addtl)) {
		ret = drbg_hmac_update(drbg, addtl, 1);
680 681 682 683 684
		if (ret)
			return ret;
	}

	drbg_string_fill(&data, drbg->V, drbg_statelen(drbg));
685
	list_add_tail(&data.list, &datalist);
686 687 688
	while (len < buflen) {
		unsigned int outlen = 0;
		/* 10.1.2.5 step 4.1 */
689
		ret = drbg_kcapi_hash(drbg, drbg->V, &datalist);
690 691 692 693 694 695 696 697 698 699 700
		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 */
701 702 703
	if (addtl && !list_empty(addtl))
		ret = drbg_hmac_update(drbg, addtl, 1);
	else
704
		ret = drbg_hmac_update(drbg, NULL, 1);
705 706 707 708 709 710
	if (ret)
		return ret;

	return len;
}

711
static const struct drbg_state_ops drbg_hmac_ops = {
712 713 714 715 716 717 718 719 720 721 722 723
	.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
724
#define CRYPTO_DRBG_HASH_STRING "HASH "
725 726 727 728 729 730 731 732
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");
733

734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765
/*
 * 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--;
	}
}

766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783
/*
 * 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,
784
			struct list_head *entropylist)
785 786 787 788 789
{
	int ret = 0;
	size_t len = 0;
	unsigned char input[5];
	unsigned char *tmp = drbg->scratchpad + drbg_statelen(drbg);
790
	struct drbg_string data;
791 792 793

	/* 10.4.1 step 3 */
	input[0] = 1;
794
	drbg_cpu_to_be32((outlen * 8), &input[1]);
795 796

	/* 10.4.1 step 4.1 -- concatenation of data for input into hash */
797 798
	drbg_string_fill(&data, input, 5);
	list_add(&data.list, entropylist);
799 800 801 802 803

	/* 10.4.1 step 4 */
	while (len < outlen) {
		short blocklen = 0;
		/* 10.4.1 step 4.1 */
804
		ret = drbg_kcapi_hash(drbg, tmp, entropylist);
805 806 807 808 809 810 811 812 813 814 815
		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:
816
	memset(tmp, 0, drbg_blocklen(drbg));
817 818 819 820
	return ret;
}

/* update function for Hash DRBG as defined in 10.1.1.2 / 10.1.1.3 */
821
static int drbg_hash_update(struct drbg_state *drbg, struct list_head *seed,
822 823 824 825
			    int reseed)
{
	int ret = 0;
	struct drbg_string data1, data2;
826 827
	LIST_HEAD(datalist);
	LIST_HEAD(datalist2);
828 829 830 831 832 833 834 835 836 837
	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);
838
		list_add_tail(&data1.list, &datalist);
839
		drbg_string_fill(&data2, V, drbg_statelen(drbg));
840
		list_add_tail(&data2.list, &datalist);
841
	}
842
	list_splice_tail(seed, &datalist);
843 844

	/* 10.1.1.2 / 10.1.1.3 step 2 and 3 */
845
	ret = drbg_hash_df(drbg, drbg->V, drbg_statelen(drbg), &datalist);
846 847 848 849 850 851
	if (ret)
		goto out;

	/* 10.1.1.2 / 10.1.1.3 step 4  */
	prefix = DRBG_PREFIX0;
	drbg_string_fill(&data1, &prefix, 1);
852
	list_add_tail(&data1.list, &datalist2);
853
	drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
854
	list_add_tail(&data2.list, &datalist2);
855
	/* 10.1.1.2 / 10.1.1.3 step 4 */
856
	ret = drbg_hash_df(drbg, drbg->C, drbg_statelen(drbg), &datalist2);
857 858

out:
859
	memset(drbg->scratchpad, 0, drbg_statelen(drbg));
860 861 862 863 864
	return ret;
}

/* processing of additional information string for Hash DRBG */
static int drbg_hash_process_addtl(struct drbg_state *drbg,
865
				   struct list_head *addtl)
866 867 868
{
	int ret = 0;
	struct drbg_string data1, data2;
869
	LIST_HEAD(datalist);
870 871 872
	unsigned char prefix = DRBG_PREFIX2;

	/* 10.1.1.4 step 2 */
873
	if (!addtl || list_empty(addtl))
874 875 876 877 878
		return 0;

	/* 10.1.1.4 step 2a */
	drbg_string_fill(&data1, &prefix, 1);
	drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
879 880
	list_add_tail(&data1.list, &datalist);
	list_add_tail(&data2.list, &datalist);
881
	list_splice_tail(addtl, &datalist);
882
	ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
883 884 885 886 887 888 889 890
	if (ret)
		goto out;

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

out:
891
	memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
892 893 894 895 896 897 898 899 900 901 902 903 904
	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;
905
	LIST_HEAD(datalist);
906 907 908 909 910

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

	drbg_string_fill(&data, src, drbg_statelen(drbg));
911
	list_add_tail(&data.list, &datalist);
912 913 914
	while (len < buflen) {
		unsigned int outlen = 0;
		/* 10.1.1.4 step hashgen 4.1 */
915
		ret = drbg_kcapi_hash(drbg, dst, &datalist);
916 917 918 919 920 921 922 923 924 925 926
		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)
927
			crypto_inc(src, drbg_statelen(drbg));
928 929 930
	}

out:
931
	memset(drbg->scratchpad, 0,
932 933 934 935 936 937 938
	       (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,
939
			      struct list_head *addtl)
940 941 942
{
	int len = 0;
	int ret = 0;
943 944
	union {
		unsigned char req[8];
945
		__be64 req_int;
946
	} u;
947 948
	unsigned char prefix = DRBG_PREFIX3;
	struct drbg_string data1, data2;
949
	LIST_HEAD(datalist);
950 951 952 953 954 955 956 957 958 959 960

	/* 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);
961
	list_add_tail(&data1.list, &datalist);
962
	drbg_string_fill(&data2, drbg->V, drbg_statelen(drbg));
963
	list_add_tail(&data2.list, &datalist);
964
	ret = drbg_kcapi_hash(drbg, drbg->scratchpad, &datalist);
965 966 967 968 969 970 971 972 973 974
	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));
975 976
	u.req_int = cpu_to_be64(drbg->reseed_ctr);
	drbg_add_buf(drbg->V, drbg_statelen(drbg), u.req, 8);
977 978

out:
979
	memset(drbg->scratchpad, 0, drbg_blocklen(drbg));
980 981 982 983 984 985 986
	return len;
}

/*
 * scratchpad usage: as update and generate are used isolated, both
 * can use the scratchpad
 */
987
static const struct drbg_state_ops drbg_hash_ops = {
988 989 990 991 992 993 994 995 996 997 998
	.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
 ******************************************************************/

999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013
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;
}

1014 1015 1016 1017 1018 1019
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);
1020 1021
	unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
	unsigned char entropy[32];
1022

1023 1024 1025
	BUG_ON(!entropylen);
	BUG_ON(entropylen > sizeof(entropy));
	get_random_bytes(entropy, entropylen);
1026

1027
	drbg_string_fill(&data, entropy, entropylen);
1028
	list_add_tail(&data.list, &seedlist);
1029

1030
	mutex_lock(&drbg->drbg_mutex);
1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042

	/* 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);

1043 1044 1045
	if (drbg->seeded)
		drbg->reseed_threshold = drbg_max_requests(drbg);

1046
	mutex_unlock(&drbg->drbg_mutex);
1047 1048

	memzero_explicit(entropy, entropylen);
1049 1050
}

1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064
/*
 * 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)
{
1065 1066 1067
	int ret;
	unsigned char entropy[((32 + 16) * 2)];
	unsigned int entropylen = drbg_sec_strength(drbg->core->flags);
1068
	struct drbg_string data1;
1069
	LIST_HEAD(seedlist);
1070 1071 1072

	/* 9.1 / 9.2 / 9.3.1 step 3 */
	if (pers && pers->len > (drbg_max_addtl(drbg))) {
1073
		pr_devel("DRBG: personalization string too long %zu\n",
1074 1075 1076 1077
			 pers->len);
		return -EINVAL;
	}

1078 1079 1080
	if (list_empty(&drbg->test_data.list)) {
		drbg_string_fill(&data1, drbg->test_data.buf,
				 drbg->test_data.len);
1081 1082
		pr_devel("DRBG: using test entropy\n");
	} else {
1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095
		/*
		 * 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));

1096
		/* Get seed from in-kernel /dev/urandom */
1097 1098 1099 1100 1101 1102
		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);
1103
		} else {
1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115
			/* 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);
1116
		}
1117
	}
1118
	list_add_tail(&data1.list, &seedlist);
1119 1120 1121 1122 1123 1124

	/*
	 * 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
	 */
1125 1126
	if (pers && pers->buf && 0 < pers->len) {
		list_add_tail(&pers->list, &seedlist);
1127 1128 1129
		pr_devel("DRBG: using personalization string\n");
	}

1130 1131 1132 1133 1134
	if (!reseed) {
		memset(drbg->V, 0, drbg_statelen(drbg));
		memset(drbg->C, 0, drbg_statelen(drbg));
	}

1135 1136
	ret = __drbg_seed(drbg, &seedlist, reseed);

1137
	memzero_explicit(entropy, entropylen * 2);
1138

1139 1140 1141 1142 1143 1144 1145 1146
	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;
1147
	kzfree(drbg->V);
1148
	drbg->V = NULL;
1149
	kzfree(drbg->C);
1150
	drbg->C = NULL;
1151
	kzfree(drbg->scratchpad);
1152 1153
	drbg->scratchpad = NULL;
	drbg->reseed_ctr = 0;
1154 1155
	drbg->d_ops = NULL;
	drbg->core = NULL;
1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166
}

/*
 * 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;

1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187
	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;
	}

1188
	drbg->V = kmalloc(drbg_statelen(drbg), GFP_KERNEL);
1189 1190
	if (!drbg->V)
		goto err;
1191
	drbg->C = kmalloc(drbg_statelen(drbg), GFP_KERNEL);
1192 1193 1194 1195 1196 1197 1198 1199 1200 1201
	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 */
1202
			  drbg_statelen(drbg) + drbg_blocklen(drbg); /* temp */
1203 1204 1205 1206 1207 1208 1209 1210
	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;
	}
1211

1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236
	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.
 *
1237
 * return: 0 when all bytes are generated; < 0 in case of an error
1238 1239 1240 1241 1242 1243
 */
static int drbg_generate(struct drbg_state *drbg,
			 unsigned char *buf, unsigned int buflen,
			 struct drbg_string *addtl)
{
	int len = 0;
1244
	LIST_HEAD(addtllist);
1245

1246 1247 1248 1249
	if (!drbg->core) {
		pr_devel("DRBG: not yet seeded\n");
		return -EINVAL;
	}
1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260
	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;
1261
	if (buflen > (drbg_max_request_bytes(drbg))) {
1262 1263 1264 1265 1266 1267 1268 1269
		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 */
1270
	if (addtl && addtl->len > (drbg_max_addtl(drbg))) {
1271 1272 1273 1274 1275 1276 1277 1278 1279 1280
		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.
	 */
1281
	if (drbg->reseed_threshold < drbg->reseed_ctr)
1282
		drbg->seeded = false;
1283

1284
	if (drbg->pr || !drbg->seeded) {
1285 1286 1287 1288 1289
		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 */
1290
		len = drbg_seed(drbg, addtl, true);
1291 1292 1293 1294 1295
		if (len)
			goto err;
		/* 9.3.1 step 7.4 */
		addtl = NULL;
	}
1296 1297 1298

	if (addtl && 0 < addtl->len)
		list_add_tail(&addtl->list, &addtllist);
1299
	/* 9.3.1 step 8 and 10 */
1300
	len = drbg->d_ops->generate(drbg, buf, buflen, &addtllist);
1301 1302

	/* 10.1.1.4 step 6, 10.1.2.5 step 7, 10.2.1.5.2 step 7 */
1303
	drbg->reseed_ctr++;
1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322
	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
1323
	if (drbg->reseed_ctr && !(drbg->reseed_ctr % 4096)) {
1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348
		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

1349 1350 1351 1352 1353
	/*
	 * All operations were successful, return 0 as mandated by
	 * the kernel crypto API interface.
	 */
	len = 0;
1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369
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)
{
1370
	unsigned int len = 0;
1371 1372
	unsigned int slice = 0;
	do {
1373
		int err = 0;
1374 1375 1376
		unsigned int chunk = 0;
		slice = ((buflen - len) / drbg_max_request_bytes(drbg));
		chunk = slice ? drbg_max_request_bytes(drbg) : (buflen - len);
1377
		mutex_lock(&drbg->drbg_mutex);
1378
		err = drbg_generate(drbg, buf + len, chunk, addtl);
1379
		mutex_unlock(&drbg->drbg_mutex);
1380 1381 1382
		if (0 > err)
			return err;
		len += chunk;
1383
	} while (slice > 0 && (len < buflen));
1384
	return 0;
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 1419 1420 1421 1422 1423 1424
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);

1425 1426 1427 1428 1429 1430
	/*
	 * Require frequent reseeds until the seed source is fully
	 * initialized.
	 */
	drbg->reseed_threshold = 50;

1431 1432 1433
	return err;
}

1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453
/*
 * 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)
{
1454 1455
	int ret;
	bool reseed = true;
1456 1457 1458

	pr_devel("DRBG: Initializing DRBG core %d with prediction resistance "
		 "%s\n", coreref, pr ? "enabled" : "disabled");
1459
	mutex_lock(&drbg->drbg_mutex);
1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470

	/* 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 */

1471 1472 1473 1474
	if (!drbg->core) {
		drbg->core = &drbg_cores[coreref];
		drbg->pr = pr;
		drbg->seeded = false;
1475
		drbg->reseed_threshold = drbg_max_requests(drbg);
1476

1477 1478 1479 1480 1481 1482 1483 1484
		ret = drbg_alloc_state(drbg);
		if (ret)
			goto unlock;

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

1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496
		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");
		}

1497 1498 1499 1500 1501
		reseed = false;
	}

	ret = drbg_seed(drbg, pers, reseed);

1502 1503
	if (ret && !reseed)
		goto free_everything;
1504

1505
	mutex_unlock(&drbg->drbg_mutex);
1506
	return ret;
1507 1508 1509

err:
	drbg_dealloc_state(drbg);
1510 1511
unlock:
	mutex_unlock(&drbg->drbg_mutex);
1512
	return ret;
1513 1514 1515 1516 1517

free_everything:
	mutex_unlock(&drbg->drbg_mutex);
	drbg_uninstantiate(drbg);
	return ret;
1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530
}

/*
 * 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)
{
1531 1532 1533 1534 1535 1536 1537
	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;
	}

1538 1539
	if (drbg->d_ops)
		drbg->d_ops->crypto_fini(drbg);
1540 1541 1542 1543 1544 1545 1546 1547 1548
	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
1549 1550
 * @data test data
 * @len test data length
1551
 */
1552 1553
static void drbg_kcapi_set_entropy(struct crypto_rng *tfm,
				   const u8 *data, unsigned int len)
1554
{
1555 1556 1557 1558
	struct drbg_state *drbg = crypto_rng_ctx(tfm);

	mutex_lock(&drbg->drbg_mutex);
	drbg_string_fill(&drbg->test_data, data, len);
1559
	mutex_unlock(&drbg->drbg_mutex);
1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578
}

/***************************************************************
 * 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)) {
1579 1580
		pr_info("DRBG: could not allocate digest TFM handle: %s\n",
				drbg->core->backend_cra_name);
1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607
		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;
	sdesc->shash.flags = 0;
	drbg->priv_data = sdesc;
	return 0;
}

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);
		kzfree(sdesc);
	}
	drbg->priv_data = NULL;
	return 0;
}

1608 1609 1610 1611 1612 1613 1614 1615 1616 1617
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)
1618 1619
{
	struct sdesc *sdesc = (struct sdesc *)drbg->priv_data;